Digital Technical Journal, Volume 8, Number 3 Dtj_v08 03_1996 Dtj V08 03 1996

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I
INTERNET PROTOCOL V.6

Digital

PRESERVATION OF HI STORICAL
COM PUTER SYSTEMS

Technical

FORTRAN FOR PARALLEL COM PUTING

Journal

SERVER PERFORMANCE EVALUATION
AND OPTIM IZATION
INTERNET COLLABORATION SO FTWARE

Volume 8 Number 3
1996

Editorial

The !)fgiwl 'f(•cbuical.foumal is a refereed

The folloll'ing arc rradem,11·ks of Digital

)an� C. Bl.1kc, ;Vl;ln;1ging Editor

journJl published quarterly by Digital

Equipment Corporation: AlphaServcr,

Helen

Equipmenr Corporarion,

L. Pattnson, Editm

Kathleen M. Stetson, Editor

Circulation
Catherine M. Phillip>, Administrator
Dorothc� R. C1ss;1dv, Sccrct<1ry
Production

T�rri Auticri, Production Editor
Ann� S. K�tzcff, T)'l.lOf'.L1phcr
PetcT R. \.Yoodhury, Illustrator

Advisory Board

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on rhe lmcrnct.

t.lkenlw Chuck Cilkttc ofsh dil'<:rs 11·ho

timmrion.

set a rcwrd in October 1996 tilr rhc lllllll
of Digit�I\ Corporate Design (;roup .

The· COI'l'r dc:sign is 111' l.ucincb O'Neill

& Associates,

J\t!EMORY CH ANNEL is <1 tr<1detmrk ot·
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fne.

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ISSN 089R-90 I X

Orack7 is :1 tr;Jckmark ofOr�de Corporation.
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trademat-ks of Sun Minosvstcms, Inc.
SPFCint is <1 tradcm:Jrk of the St�nd;1rd
Pcrtimn:HKe b·;1luarion CotHKil.
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Svbase, Inc.
TPC-C is a tr;�ckmark of the Tt-;1nsacrion

Documetlt,Jtion ::--lumber �:C-;-...17285-18

Processing Pt'rt()rm;lncc Coun..:il.

Book production \\'aS done bv Qun.

be construed .1s .\ cnmmittnenr bv Digit<11

(CllllllH111iGHion. The sr.tphic ()l) our({)\'(]"

r rhc purpose of

INI-'ORNIIX and INI-'ORMIX-OnLinc

nH:Teir rmance that can he

computing histon·. The re-creation,

dcri1·cd ti-om a I'Crl' bst intnconnecr

both p h ysica l and logical, ofcompur

p•1pcr demonstrates how easv it is to
build J S\'Stem that would ha1·c been

,md sofr11arc srructu1·es ro m.ltch.

•1 111ajo1- f)rojccr just fin: v c11·s <�go.

ing S\'Stcrns ofthe past on onII- he! p

·rhe pcrr(>rm•wce Je,·cls •Khic,·ed

This case of construction is a bcnctit

remind us that the artif:Kts 11·c crcuc

sh,lttcr 11 orld records on a bench

ofthe programming techniques and

ha,·c a longer lire than we anticipate.

mark that Ius l1ad exrensi1·e atten

infi·,lstructurc im·estments and J spur

As our programmers write new code,

tion .md ll'ork.

to keep doing more ofit.

or our hardw:H"C designers produce
new architectural approaches, or our

The other pr m :�ki n g the u l timate decision . I n J u ly

1 994, the 1 Png d i rectora te selected

the

the evol ution of the pJc ke t t(mnat
hender. I t retai n s som e ti c l d s ( ve r 

is rcn:� med t h e H o p Li m i t ) , a n d i n trod uces n ew o n es

I nternet

( s u c h as Fl o\\' l D ) wi t h as vet u n tapped potcmia l . The

Protocol \'CI'Sion 6 ( l l"·6 ) as t h e repbce mc n t n c t\\' or k

ne xt hudcr

J a ,·e r p rotoco l , Jnd I ETF \\'orki n g groups bega n to

ticld ai iO\\'S fo r m od u l a r constr uction o f

complex p�1c ke ts : d i ffere n t h eade r t\vcs em he c h �1 i 1 1 cd

b u i l d spe c i fi cati ons . "The Recom m e nd ation t( >r the

toge th er to pro,· i d e speci a l i z e d tu nctio n a l i rv, i n c l u d 

I P Next Ge n e rati on Protocol" su mmarizes the c1 11d i 

i n g sec u r i t\' a n d source routing. h n a.l l v, a l l hc:�dcrs arc

d a tcs �m d c xpb i ns the selection of this

p rotoco l . '

s t r u c tured to a l l o\\' 64 - b i t alignment, \\'h ich shou l d
a l l ow opti m : d p rocessi n g both a t source a nd desti n a 
tion systems, as \\'ell as i n transit '

Digital UNIX Prototype

Th e c u rrc l l t Di gi t:� I U N I X 1 Pv6 p rototype p roject is

Th e most stri ki n g d epa rtu re ti-om

is the

:�d d rcss s i t.c : i t has i nc reased from 32 b i ts to 1 2 8 bits.

d eve l op a n d e va l u ate

The J P\'6 ad d ressi n g arch itecture is ri c h , with p re fi xes

the co mpe ting I P n g p roposa l s .

This began w i t h t h e S i m pl e I n ternet Protocol ( S I P ) ,

t( Jr m u l ti cast a d d resses and p rc d c ti ncd

which used e ight octet ad d resses . S I P was later melded
with another ea rly proposal a n d bec a me kn o w n as

u n icast and m u l ticast a d d resses. One s peci a l type of

u n ica s t �1d d ress is tl1e l i n k - loca l add ress , w h i c h pe rm i ts

S i mp l e I n ternet Protocol

comm u n i cations \\'i t h on l y t hose syste ms d i rectl y con

P l u s ( S J P P ) , the d i rect

a

scopes rcJr bo th

a nteced e n t of ! Pv6 . ' Th e p r i ma ry goa l of D igi ta l 's

nected on the same l i n k . Th is a l l ows

cftC>rts has b ee n to ev:� l u ate the tec h n i c a l fe as i b i l i ty o f

s trap pi n g mecb:�nism, so that S\'Stc m s can lc�1rn a b o u t

the proposed :� rc h i tcct u re and p ro,·id e k e d bac k to the

op tio n s h�1\'C

been d e fi n ed , i n cl u d i n g hi er:�rchical
models based u pon regional 1-cgisrries �1 n d sen·ice

tiple i ndependent �md interoperable i mplcmenutions
�1

stan (brd boot

ne i g h bo rs a n d scn·ices before a ro u r :� bl c :� dd rcss i s
�1 ssi g n ed to an i n terrace . Va rious ad d res s :.� ssi gn mc n t

\\'Or ki n g gro u p s . This is critical to the s t:� n d a rd s
dC\ e lopmel l t process in the I ETF, ,,·bich req u i res m u l 
I ETr

spccitic:�tion bdore it ma\' become a n I ntern e t

p rm·id c r i d c n t i ti e rs .' n I n each case, care h:�s been ta ken

sta n d a rd . An a d d itional goal has been to e,·�1 l u arc svs 

to e ns ure p ro pe r m u te aggrega tio n , \\ hich \\'i l l h e l p

rcm d esi gn :� l te rnativcs to gain the expe rien ce needed

vi c ki more e ffi ci e n t b:�ck bone router pcrt(mn�mcc .

of

M u l tip l e mc:�ns of acq u i ri n g add resses have been

to a l low D i gi ta l to i ncorporate t h is nc,,· :� rc h itccru rc

i mo e x isti ng p rod u c t s . D i gita l h :� s mad e the protot pe

dcti ncd t(Jr J P, 6 add ressin g, wi t h

y

Jva i b bl c to rcsc ::1 rc he rs with i n the company as �1 source

V E RSION

I

P R I O R ITY

I

I

NEXT H E A D E R

SOURCE ADDR ESS

DESTINATION A D D R ESS

F i g u re 1
1 1\·6 H e ader

Digi r:d Tcclmic.ll jou rnal

Vol . 8 N o . 3

l 'o/9 6

the go:� l s o f a l l o\\'i ng

tl c x i b i l i t\' t h rou gh d i fferent a d m i n istrative po l ic ies

FLOW LABEL

PAYLOAD LENGTH

6

I l'v4

D igi ta l ' s most recent add ition to an on goi n g cHc>rt to

I

HOP L I M I T

and , p e rhaps more i m port J il t , o F d e m J n d i n g that net
work add ress r eassi gn m e n t be supported t h roughout
the an: h i tectu re . T h e two new :1dd rcssi n g services are

EJ

Statel ess A d d ress A u roco n tigu ra tion a n d t h e state fu l ,
transac tion - b:.1scd Dynamic H os t Confi gu rati on P ro 
tocol version 6 ( D H C P,·6 ) . c s I n t h e stateless mod e l ,

add ress prefixes a rc learned lw l i s te n i n g fo r rou ter
ad\-ertise m c n t packers . A d d resses a n: t( J rmcd bv com
bi n i n g the p r e fi x ,,· i t h a l i n k-specific token such as the

4 8 - b i t Ethernet h a rdware a d d ress . I n the stateful pro 
ccd ure, hosts ma\' req uest Jdd resses, con fi gu rati on
i n formation, and services tl·om d e d icated confi g u ra 

USER
KERNEL

res u l t i n g a d d n:sses have associated l i fe ti mes, and sys
tems m ust be prepared to both lea rn new add resses
a n d release e x pi red add resses. Combi ned with the
a b i li ty to register updated add ress i n formation with

NETWORK
COMMANDS
AND U T I L I T I E S

TRANSITION
MECHANISMS

I Ll
I
8 El
I
I
so c KET LAY E R

TRANSITION
MECHANISM

DYNAMIC

N ETWOR K LAYE R

ADDRESS

tion sen·ers, with routers pote mi a l l y sen·ing a s rel ay
stations d u ri n g t h e i n i ti�1! phase . I n both cases, the

I P-BASED
A P PLICATIONS

__________J
s E c u R I TY

ROUTING TABLE
AND N E IGHBOR
CAC H E

N E I G HBOR
DISCOV E RY

L I N K-LAY E R
MODULES

I PV6/IPV4
T U N N ELS

F i g u re 2
Base Platform Cha nges

DNS servers, these mecha n isms provide a path toward
n e twork re n u m berin g ,

a

goal thJt has proved d i ffic u l t

t o ach ieve i n t h e l l'v4 world .
Final ly, the I nternet Con tro l MessJgc Protocol ver
sion 6 ( I C M Pv6 ) >vas d eve lop ed ." This specification
aimed to

m erge the fu nctions o f two d istinct I Pv4 pro

tocols tor report i n g errors and status, I C M P to r u n i 
cast packet transm ission a n d t h e I n ternet Gro u p
Message Protocol ( I G M P ) tor m u l ticast traffic .
The messages ddi ned i n this protocol arc catego
rized JS either e r ror or i n t(mnational , with a fa m i ly of
messages i n the second gro u p used to prov i d e the
Neigh bor DiscO\·e r v P rotocol . ' " Neigh bor d iscov e ry
ser v es m u l tipl c p u rposes with t h e O\'crJ ! I t h e m e of
p r m· i d i n g a system \\' i t h to pological a n d e n v i r on me n 
tal h i ms . F o r e xa m p l e , l i n k - l aver J d d rcss reso l u ti o n ,
rou ter d iscovcrv, d esti n a ti o n a d d ress red i recti on , and
:� d d rcss a u roconfigu r:�rion mecha nisms arc :� I I spec i fied
usi n g neighbo r d iscO\·erv packe t tvpes.
Although the network layer did experience the l argest
Jmoum of change, Figure 2 shows that t h e effects of
this work tou c h nearly all aspects of the Digital U N I X
system . We point o u t examples ofdccisions nude d ue to

our

fu n d a m e n t: tl d es i g n

philosophy, which is based

u p o n i mcg ration with the U N IX system trJ m cwo r k,
mod u la r Jlld extensible sofuv:1rc, su pport tor m u ltiple
ope ratjo nal policies, and J desire to take
the Alpha pla t tcmn without

a d vantage

of

com p romisi ng portabi lity.

I n t h e t(J!Jowi n g sections, we study these topics i n
d e p th , begin n i n g with t h e network layer, then cover
ing t h e transport layer rnod i ticJtions a n d the

n ew

neighbor d i s cove ry algori t h m s . Alte r that, we d i scuss

Jdd ress

a u toconti g u rJtion

mecha n i sms

and

their

e ffects u pon the svste m . W e concl u d e wi th services
t hJt will be a fft:ctcd by the transition tl· om I Pv4 to

Network Layer
In t h is section , we rn· i cw the p rocessing req u i re m e n ts
of t h e I Pv 6 m od u les , i n c l u d i n g I C : M Pv6, extension
header op ti o n s , a n d ti·Jgmcnta tion . A n early d esign
decision was made to base the networ k i n g su bsystem
o n the B erkeley StJmiJrd D istri b u tion ( B S D ) 4 . 4
m o d e l a n d c o d e base , w h i c h J ! !ows great tlcx i bi l i ry i n
d e al i n g with m u l t i p l e n e twork layers . 1 1 ·rh i s ::dso h ::1 s
the ad\'an tage of pro vid i n g s u pport tc) r vJri�l b l c - bi t 
l e n gth net masks ( also known a s

Cl D R-stvlc nctm asks ,

fro m C l assless I n tcr- Dom J i n Ro u ti n g ) , w h i c h �1re
appropria te to b ot h I p, 4 Jnd I p,·6 . " We ha,·e :� I so
tried to take m Jx i m u m ad,· a n tage of the 64 - bi t A l p h J
a rc h i tecture when i mp l e m e n t i n g I p,·6 , w h i l e ma ki n g
certain that this i m pl e m enta ti on \\'O u ! d r u n on 3 2 - b i t
C P U s as wel l . For c x J m p l c , t h e c h ecks u m rou ti nes
operate on 3 2 - b it q u a n tities ( a l lowing t h e GI ITV ro
ove rflow i nto the upper 32 b i ts o f J 64 - bi t registe r ) .
T h e checks u m rou t i ne i s a lso designed t o a l low i t t o b e
issu ed t o m u l t i p l e A l p h a exec u ti o n

un its, which

remains a topic tor fu rther i n vestiga tion .

Adaptations to Existing IP and ICMP Routines
The

1Pv6

and

I C M Pv6

rou ti n es

J rc

completely

i n d e pe n d e n t of the cor r espond i ng 1 Pv4 and I C M Pv4

r o ut i n es , and the processi n g styles have d istinct d i fk r
e nc es .

In

l Pv6, the inco m i n g packet is treated as bei ng

r e a d - on ly, w h i l e the B S D 1 Pv4 code m a n i p u ! J tcs fields
wi th i n the lPv4 header. We also avoi d u n neccsS:Jrv usc

;

of the m_ p u l l u p routine ( w h i c h conso l i Lbtes ch i n cd

lPv6 such as the socket J p p l i cnion p rogra m m i n g

me mory b u ffers i n to a single l a rge b u fk r ) bccJusc t h i s

i ntcrfJce ( A P I ) a nd D N S .

c o u l d cause the packet to be necd lcsslv lost. F i n a l l v
·
i n s tead o f p assi ng n u mero us cl rgu m en t w h e n c a l l i n

�

�

from fu nction to nmction, a COI111110n cbt J structure is

Digital Tec h n ical J o u rn a l

Voi . R ::--.J o 3

1 996

7

used to store ncccssarv d J t: l a n d p o i n te rs ; r(Jr most
rl.1 n ction c a l l s , i t is o n l y necessary to p�1ss a poi n te r

first valid ated fo r correct packet r(m11Jt :� n d c h ecks u m .

The packet is t h e n rL! rthcr processed b�1scd u pon i ts

t o t h i s structure. T h i s red u ces t h e stack overhead a n d

I CiV!Pv6 type va l ue . I f i t has an I C : M l\·6 error type ( i .e . ,

a l so \ ' i c l d s m od u l a r <1 11d c a s i h · extensi b l e s u bro u t i n e s .

tvpe v a l u e J ess t h a n 1 2 8 ) , t h e a p p ropriate notifications

I P,·6 has a d e d icated i n t e r r u p t processi n g th read ,

are sent to the a fkcted protoco l . Neigh bor d iscovcn·

and rccci ,·cd 1 1".·6 packets J rc p l :�ccd onto t h e i r own

packets , which arc al l i n r(mnati o na l , hJ\'C a n u m be r of

i nt e r race i n p u t q u e u e ( i fl1 u c u c ) . When an l P\ 6 packet

a d d i tion<1 1

is taken off the i f(] u c u c , basic ,·a l i d i tv tests are d o n e ;

d ropped if it h i l s the m . Afi:er the I C : M P,·6 packet has

is d i rected t o  The to rmer yiel ds the d esirable larger

O R I G INAL PACKET

FRAGMENTABLE PART

U N FRAGMENTABLE
PART

FRAGMENT PACKETS
UNFRAGMENTABLE
PART

U N FRAG M E NTABLE
PART

U N FRAGMENTABLE
PART

F i g u re 4
Fragmenrarion
Digir�l Technic\! ) o u rn ;\l

Vol . 8 No. 3

1 99 6

9

p:1ckers , w h i l e the l :mc r :1 \'o i d s u n de s i ra ble fragm ent
loss ( d ue ro t he tr:1 gm en r p a ck e t b e i ng too bi g ) . T h e
D ig i ta l U N I X 1 Pv6 p rototv p e su pports either choice
on a s �·stem -wide , per - d es r i n :lt i on, or pe r- sock e t basi s .
T h i s i s J n cx:1mpk of separJtion of m e c h J n is m trom
pol icy, J bJsic gu i d e l i n e bei n g used across this project.
Reassembly

rcasscm b l v process r ec o n st ru c t s t h e ori g i n a l
p a cke t ti·o m tra g m e n r p�1c kets. F ra gm e n ts be longing
to the same p<1cket a rc i d c n ritied b\' J combin:1tion of
so u rce I P J dd rcss , not h e a d e r tYpe ( fi rs t h e:1dc r of the
tr a gm e n t•1 b lc p:1rr) and ri·a g m c nt i d e n t i fier. I n d i ,· i d m l
fi· J gmc nts arc queue d wi t h i n the network l aver until the
orig inJI pac ker c J n be co m ple tc l v reassembled, at which
p oi n t i t i s pa ss e d to the appropriate p ro to co l m od u l e .
\Nhen :1 l l fr agme ms h �l\'e arr iv e d , the origi n a l packer
can be n.:as se m bl cd . A s i n gk copy of thc u n tra gm e n r 
Jble part is kept , Jnd the data from ea ch ti·a g m en t
packet is ap pen d e d . The p :1 y lo :1d len gth fie l d of the I Pv6
header is u p dated to rdkct the le ng t h of the reasscm
bkd pa c ke t , and the next hc;�dcr ticld of the last header
of the u n ti·agmcntablc par t is restored to rdlect the fi rst
header in the ITa g m c n tJbl e p Jr t.
As with the ti·:lgmc ntJtion c o d e, care must be ta ke n
so thJt ti elds b ei n g u p lhtcd arc not in bu ffers shared
with other cop i es of t he p J c kc t .
When the tirs r tl-:1 gm c nt of J p Jc kc t arrives, J ti mer
is s ta r ted . I f the rimer expires bdo rc th at p ac ke t is
co m pl et e , the tr:1g mcnts Jre d isc;�rded . I f the othe r
zero tra gmcnr h :1s been rccci,Td, Jn I CM p,·6 error
message is sent.
The

Forwarding and Routing

! f a rcccin.:d pa c ker docs nor m:nch one ofrhc S\'Stc m 's
Jnd the svstc m is not J c tin g :\S a rou ter, the
packet is s i l c nr lv d ro p p ed . Othcn,·isc, an attempt is
made to t()rW:lrd t h e packet. The �i rst step in torward 
ing i� to do :1 lookup in the rou t i n g t:tblc; t h e tvpe of
look u p de pe nds on whether the p a c k er contains a
nonzero tlow bbcl. I f i t docs, the lookup is based o n
both the source :1d drcss Jnd the tl ow label; othe rwi se
the destination add ress is used. If the l ook u p su cceeds
and the len gt h of r h e p:1 c k c t tits within t h e MTU of rhc
resu l u n t route a n d i n rc r �ace , the packer is tr J n s rn i t re d
to r h c next hop :\S i n d i u rcd by the ro u t e . O t h e r wise
an appro p ri a te I C M Pv6 e r ror is sent back to the origi
n a t i ng n od e .

add resses

Tu nne l i ng is a mechanism that J l l ows pa ck ets of one
network type to be e n c 1p su l � nc d :lllli to nva rded wi thin
a n e tw or k layer p a c k e r of r h c SJnH:: or a d i ffe re nt rvpe .
J P,-6 pa c ke rs CJil be ru n n c l cd over e i t h e r I P,·4 or 1 Pv6
ne twor k s , JS m:w I p,.4 p :1 c kc ts 1"r T h e tu n n el i ng rou
tine r:1 kcs as i np u t a p :1c kc t, p rep c n d s t h e ap p ropr i a te
Tunnels

10

Vo l . 8 No 3

1 996

h e a d e r tor t h e network ove r which the packer wi l l
be tu n n el ed , :1 nd trJnsmits r h c re s u l ta n t p ac ke r m·cr
rhar n etw ork . Tu n nels JI'C unid irccrionJI; there need
not be a co r res pondi ng tu n ne l in the reve rse d i recti o n .
Rather thJn h :l\'ing m u l ti pl e tu nnel i nrcrtaccs (one
tor e J c h p o ssi b l e combi nation of protocol Y 0\·er
protocol X ) , the D i g i t:1 l U N I X i mplem e nt at ion uses
a si n gle runnel i nrcrtac c . This method was the sugges
tion of Ke ith S kl c m e r of the Un i,nsit-v of C:-� l i torn i:-�
ar Berkc lc\'. 1 8 Wh e n th e i n te r race is i n i ri �1 l i ze d , on l\·
:l u to m a ric t u nn eli n g o f I p,-6 over I 1'\-4 is cn:1blcd . 1 ''
To confi gu re :1 static tu n n e l , w h e re ti \cd e n d po i nts
are use d , a sutic ro u te is �1d d cd to rhc ro u tin g t:lbles
wid1 the proper d e sti n a ti on a n d gJt C \\ 'J\ ' ( ru n n e l e n d
poi nt ) ad d re s se s.
'vVhen J pa c ke r i s p re se nte d to rhc ru n n e l i n te r race,
i t looks up the route entrv of rhc desti nation address.
The route co n te nts te l ls the tu n n e l in g rou t i n e how the
packer is to be e ncJ ps u iJ tcd and t()nva rded . T he route's
gateway address i n d ic at es w h a t u n d c rlv i n g network to
use, and t he rou te's d estination add ress ind icate s w h rt was the co m 
to preserve the \\'e l l - u n d e rstood r r:� ns po r rs,
TCP Jn d U D P , upon w h i c h a \\'CJi t h of app l i cn io n s
hJ,·e b e e n b u i l t .
The 1Pv6 s pc c i fi c J t i o n c:-� l l s r(>r thr ee pa r r i c u l �1 r
re q u i rem e nts of u p pe r- l aver p ro toc ols :
One

m i r ment

1 . The pse u do h e a d e r c h e c ksu m must accom modate
larger Jddresscs.
ma \ i m u rn
m p u ted .

2. The
co

p:1c kcr

l i tctimc

1s

no

lon ge r

3. The l a rge r I P\'6 hc:-�dcr( s ) m u s t be Ll ken i n to
acco u n t when c o m p u t i n g the 111 3 \ i m u m p::tylo�l<.i
size ( e . g . , TC I)'s m J \ i m u rn seg m c m s i z e [ M S S ] ) '

I n J dd i tion ro th e se ma n d ate d mod ifi ca tions, we h ad
to nuke a fu ndJment:ll design ch oice . With rwo d i ffe r
e n t ne tw or k l a y e r protoco l s in th e syste m, each u s i n g a
d iftere n r si ze :-�ddrcss, our design c hoice c o u l d h J ve
been ro use two i n depe n de nt tra ns port mod u les, one
fo r each n e twork l a ye r. fi g ur es 5 a n d 6 s h ow the i nde
p e n d e nt versus th e i ntcgr� ue d t ra ns p ort de sig n op ti o ns .
Although the i nd e pe nd e nt model oftc rs an clement
of d es ig n sim p l i c i rv, i t w:l stc s memory by d u p licati ng
e a c h transpon l ave r ti.mcti o n . I n t h e Digital U N I X
i m p l e m e ntat i o n , these modu les JIT i m p le m e n te d in
the k e r n e l , and d u pli c a ti o n \\ O u l d be ex p e n si ve . Also,
the d e s i g n :1nd usc ot' a si n g l e p ro g n m m i ng i mcrLKc
to acce ss both sets of scn·iccs wou ld be c o m p l i c :l te d .

SOCKET
LAYER

�� - - - - - - - - - - - - - - - 1
KERNEL

rPC'Bl--i
� I

AF_INET
V4 TRANSPORT
I PV4

I I
I I

AF_IN ET6
V6 TRA N SPORT
I PV6

_

_

�rPC'Bl
I �

Al though the concept of a sockad d r i s generic i n the
BSD arch i tecture, the tl ow l abel a nd i n 6_ad d r mem 
bers of t h is structure are u n i q u e to I Pv6 a n d wou l d be
used o n l y in the AF_INET6 add ress fam i ly. The detai ls
of this are specified in Reference 2 1 .
The i n_pc b data structure is created for each socket
using TC P , U D P , or other c lie nts of the net\vork layer.
In :-td d i ti o n to stori n g the sou rce and d estination
addresses, various other pieces of i n tonnation req u i red

F i g u re 5

tor proper communication are stored here, i n c l u d i n g

Indcpcndcnr Tra n spo rt 1 mple m e n ration

the p o r t n u m bers, options a n d tl ags , a pointer r o the
socket receiving the d ata , a header te m p l ate, and a
SOCKET
LAYER

�� - - - - - - - - - - - - - - - 1
KERNEL

AF_INET/AF_INET6

�r-

V4 A N D V6 T RA N S P O RT
:::::::
�::::::::: -��: :
�
, Pv4
_
_

...
L
_
_

_.1 �-�--'_P_v6 _.1
_

-

_

_

pointer ro the routi ng entry tor the given desti natio n .
F o r 1 Pv6, this basic model h as bee n retai ned, a n d addi
tional i n formation is stored . This i nformation incl udes
l ocal and remote tl ow l a bels a n d i n d i o tors of which

, PC B

I

�

_

address family the application is using a n d which net
work layer the transport com m u n ication is u si n g .
F i n a l ly, a partial checksu m o f t h e transport pseudo
header i s stored here as well ; its usc i s described in the
fo llowi ng secti o n .

Fig u re 6

I n addition t o the e x p l i c i t storage of the JKt\vork

I n tegrat ed Tran spo r t I m plementation

layer and address fam i ly, the fu ndamental tech n ique
that fac i l itates the use of a common tra nsport is the

The a b i l ity to maintain, let alone exte n d , the code base

storage o f I Pv4 add resses i n a n I P\·6 format. This is

wou ld a lso su ffer. Fortunately, d u e to the fact that

known as a n 1 Pv4 - mapped a d d ress a n d is described

I Pv4 add resses are a well -defi ned su bset o f the e ntire

i n "IP Ve rsi o n 6 Add ressi n g Arc h i tectur e . " 2 0 This

I Pv6 address space , it is rel a tively straightforward to

a d d ress fo rmat is expl ic i tl y reserved to store add resses

i mp l e m e n t the transports so that a single set of mod 

of systems that arc capa b l e of u s i n g o n l y the I Pv4

u l es can be used over both network layers.20 To accom 

protocol , and rhus is an appro p riate form of storage

p l is h this, w e i nc reased t h e storage space aLlocated

in t h e PCB for comm u n ications that wi ll be sent using

tor add resses and separated those fu nctions that arc

the I Pv4 protocol, as opposed to fPv4-compati b l e

dependent u pon

a

particular n e twork layer. vVe discuss

OOOO : OOOO : OOOO : OOOO : OOOO : F F F F : 204 . 1 2 3 . 2 . 75

Storing Large Addresses

Two spec i fi c data structu res m ust be m o d i fi e d to
accommod ate add resses l a rger than the 3 2 - bi t 1 Pv4
ty pe . The fi rst of these is the sockaddr struct, which i s

used w h e n deal i n g with t h e B S D socket layer and
passed

alon g to user appl ications. T h e secon d is the

I n ternet Protocol Con trol B lock ( PC B ) data struc
ture , the i n_pcb. I n this secti o n , we review the modifi 
cations t o each structure.

A program that uses a transport does so by means of
the BSD sockets i nt e r face and passes address i n g i n for

m ation in a sockaddr str ucture. For 1Pv6, this is a

sockadd r_i n 6 . I n te rn al ly, the structure is d e tl ned so
that 64 - bi t ali gnment is preserved; however, it has the
fo l l owi ng p u b l i c defi n i tion :
st ruct

} ,.

sockaddr

addresses, w h i c h are sent using I P v 6 packets. These
mapped add resses are o f the fo l lowi n g form :

each of' these issues in this sectio n .

i n6

These add resses arc m a n i p u lated with i n the I Pv4
TCP a n d U D P protocols by means of macros that
a l l ow the I Pv4 add resses to b e i n serted , extracted ,
or compared w h i l e in

(in6_addr) . As an

I Pv6 address structure

t!·agmcnt in

F i gure 7 shows a n add ress bein g extracted tor use
in eva l u ating a conflgurable 1 Pv4 socket opti o n .
Special Transport/Network Layer Interactions

W i t h i n the integrated transport layers, the transport
protocol i s treated independently o f the particula r
n e twork l a y e r being u s e d , a n d n e t\vork - l aycr-speci flc
functions are used to i n terface to either I Pv4 o r 1Pv6.
There are

{

an

example , the code

t\vo partic u l a r i nstances i n which the
i nteractions with the 1 Pv6 nct\vork

transport l ayer has

u_ c h a r
u_ c h a r

s i n 6_ l e n ;

layer over a n d above the excha n ge o f· d ata packets tor

s i n 6_ f a m i l y ;

u

s i n 6_p o r t ;

i n p u t or output. These are the notification a n d u pdate

short

u_i n t
struct

s i n 6_ f l o w l a b e l ;
i n6

addr

s i n 6_a d d r ;

o f path MT U , w h i c h is req u i red in 1 Pv6, and the
pote n t i a l to refresh the neighbo r d i scovery cache
based o n f(xward progress; i . e . , i f the transport knows
that d a ta is reac h i n g i ts destinati o n , it can val i d ate the

Digital Technical

Journal

Vol . 8

No. 3

1 996

II

I*
* T e s t a d d r e s s f o r ! Pv4
*I
i f ( i n p - > i n p_ n e t l a y e r = =

AF

st ruct

tmp;

i n_a d d r

t m p . s_a d d r

i f

character i s t i c

!NET)

{

I N 6 _ E X T R A C T _ V 4 A D D R ( i n p - > i n p_ f a d d r l ;

=

( ! i n_ L o c a l a d d r ( t m p ) )

}

F ig u re 7
Code F ragm enr of a 1 Pv4-mapped Address

c u rrent n e nvork l aye r pa th . We i n vestigate each of

occurrence on I P v6 hosts, a n d so t h e p rocess o f

these issues i n turn .

c h oosi n g a sou rce add ress to usc becomes i m porta n t .

Path M T U d iscove ry, as previ ou s ly descri bed , i s

T h e source address selection i s t\'pically d o n e w h e n

l ayer, with learned i n formation stored i n the r o u tin g

fu nction is a l so a va i l ab l e ro users of raw sockets a n d to

tabl e . In t h e course of p rocessing a PT B mess a g e , t h e

other n c t\vork - l ayer users s u c h as ICMPv6 .

triggered b y ICl v l P messages processed i n the network

transport l ayer i s notifi ed t h rough i ts control i n put

,

The source address selection fu nction takes as argu

( ct l i n p u t ) path This i s req u i red because the reception

m e n ts a d estination add ress and a n optional i n terface

of s u c h a n I C M P message i n d icates that the packet i n

po i n te r. The latter is used wh en k11 own, bu t in the case

transit has been d isca rd ed thus the protocol m ay need

of i n i tiating a transport connection i t is n u l l . T he

to take appropriate a ct i o n . In the case o f TCP, it i s

d estination rm�l t i o n to be l e a rn ed �m d the S\'Stem to a u tocon 

t:� b lc i s u p d a ted :�.s neccssa n·, b \ ' m e J n s of a ra\\' socket

encom p�lSSeS the r( > i i O \I 'i n g i te m s :
•

Ro u te r d i sco\'en·

•

O n - l i n k prdi x d i sCO\'Cl'\'

We dcs i gn cd

:t

•

l n tedace artri b u n: con tl gu ra ri o n

•

State l ess �1d d ress c o n fi g u ration

•

the I Pv6 ra \\' socket's i n re r f1cc \\'ith

the abi l i t\· to pass on \\' sp e ci fi c I C M P\·6 messages to
u se r a n d to ri l te r e x tra n eo u s packets or p rotoco l s .

The n d 6 h ostd d a e m o n sets a socket opt i o n to receive

o n l \' n c i g h bm d iscm erv R.As. It then e x e c u tes a d is 
p�ltch ro u ti n e t h a t po l l s the ra\\ ' socket, :1\\':J. i ti n g
p:� c kc rs . vVhe n d �1 ta i s �wa i l a b l e on the socket, t h e d :�c

S ra re h d add ress config u ra tion

m o n d e termines the c haracteristics o f t h e messag�.:,

The m e c h �w i s m tc l r delive r ing t hi s i n tornu ri o n
t h e h osts i s the rou ter a d \' e rti se m e n t

ro

( RA ) packer of

crc1 tcs a d a ta structure to con ta i n i t, and c:�. l ls rhc ncc

cssarv fu n c ti o n s to perform a u toconti g u ra t i o n . The

the Neigh bor D i sco\'l: ry Protoco l . I n t h e t( J I I o w i n g

d i spatch mod u l e , in add i ti o n to po l l i n g socket d escrip

sections, \\'e d escribe the m e thods w e d e \ ' C ] oped to

tors, s u p po r ts necessary t i me r m a n agem e n t fu n c ti o n s

process these p ac ke rs a n d u p d a te t h e syste m .

s u c h :�.s creation , d e l et i o n , and expirati o n . f i g u r e
s h o\\'S t h e

:t ppl i ca tion

ll

daemon design cen ter.

Host Autoconfiguration Daemon

To process these R.As, \\'C designed

:1.

hos t daemon

Kernel Interface Data Structures

c a l led nd6hos td , \\· h i c h rcsidcs i n the appl ic:�.tion space
o f th e Di gi t: d U N I X operating S\'Ste m . We d e te rmined
that

J

user- mode th e m o n \\' l l o\\·

I n nJJnv WJ\'S, the data l i n k i nt e rrace is t h e foc u s of
I P\ · 6 :� u roco n riguration support. The k e rn e l d a ta struc 

tll iTS r( > r ! P\·4 i n te rfaces arc n o t su ffic i cnt

m e n ted llC\\. i n tert:Ke data structures t h a t e nopsu l a te d

•

A user- mode daemon \\'O u ld a\·o id kern e l bloat.

•

M a i me n �1 nce a n d exte n s i b i l i t\' would be c1sicr.

•

The nmction is not pe r rorm a nce cti t i ca l .

the o i sti ng I f\·4 stru ctures . This a l ltl\\nl u s to :1. \ · oi d a

rccom pi l a ti on o f the ex isti n g d a ta l i n k d ri\·crs on the
D i g i ta l U N T X operati ng S\'Ste m . In t h e fu t u re , \\'e \\' i l l

a ttem p t J design in \\'h i c h the i n terbce s tructu res rclr

The a ur o c on tl g u ra ri o n process i n g is i m ple m e n ted
as a si n gle executable i mage , as a cohesive set o f tig h tlv
cou p l e d mod u l e s . T h e d:�.emon c ur re n t l y i s d esigned
as a si n g l e - t h readed appl ication that uses a d i sp:nc h

mech�1 n ism to c a l l each spec i a l i zed function mod u l e i n

t u rn . We w i l l c x :1 m i n e t h e i d e a of b a \ ·ing t h i s d a e m o n
r u n as a m u l tith re a d ed a pp l i ca tion i n the rtl tlii'C .
The n d 6hostd daemon commun icates "·i th t h e
nct\n>rk su bs\·srcm i n the kernel th rough m u l ti p l c
tec h n i q ues. F i g ure

10

s h O\\'S the

au rocontigmarion

process i n g mod u l es . 'The Ll\\' socket i nt e r race is used to

recci \·e 1\As, :md 1/0 control messages ( ioctl s ) :�rc

ROUTER
D ISCOVERY

i

ON-LINK
PREFIX
DISCOVERY

i

u sed

I l'\'4 and I l'v6 arc completely i nt e grated .

As shown in F i g u re 1 2 ,
structure

to

Ethernet,

! ' P I' ,

s u pport

l o o pb a c k )

J l'\·6

:1 d d rcss

co n ti g u re d

(e.g.,

existing

in

the

d :� t:J.

str u c tu re

mell t l i n k - h vf'r

option of the RA is then added

Digjul 'Ji:l'hnical Jounl:ll

to the

ro u t

i n g r.1hk,

17

AUTOCO N F I G U RATION
I N T E R FACE AT TRIBUTE
PROCESSING

U S E R SPACE

IOCTLs
SIOCIPV6ADDRTR
SIOCIPV6DELRTR
SIOCI PV6 1 F I N IT
SIOCI PV6A I FADDR
SIOCIPV6SI FATTR

-

- - - - - -

K E R N E L SPACE

SIOCIPV6 G I FATTR
SIOCI PV6MIFADDR
SIOCI PV6GIFADDR
SIOCI PV6D I FADDR

- - - - - - - - - - - -

I PV6 I NT E R FACE CONTROL M O D U LE
A D D R ESSES AND STATE
ON-LINK P R E F I X E S
R O U T E ATT R I BUTES

DATA LINK ATTRI BUTES

F i g u re 1 3

l nrcrt:Kc

Artrib urc Upd � rcs

e d e leted ,,· h u 1 .1 I l l'\\ 1\. \ prc�c n h t l 1 c J'i'C
tix \\ i t h a li ktimc of zero . In that c.t s c , the o n - l i n k
prdix mod ule will stop the rimer rou t i n e and de lete

the

1 l 1 e 1 > I L' I I .\ I I ' 1 1 1 1 I I J c l l l l l l l l l t!. i .t i J I L- .

\

l l l . ti .

'"

ad m i n i s trators wi t h c o n t rol O\'er the usc of ne t\\'ork
add resses without m a n u a l i n tcr\'c n tion of each host o n

The daemon :-�dds the prdix to the routing ta ble.

I l ' !l' i .d I c< i l l l l l . d ' " " " " d

pcrmi ttcd ( as

comm u11 ic:� tions

r(lr u s e rs
need tig h t control over add ress co n fi g

rile network. The state l ess model i s i n tended

The l e n g t h of t i m e the prdi x i s \'d . h !j l l l 'l' 1 -! o,IH I\1'� t i ll' l c l c i i C "
.

\VIwn rlw c� w m n n ,.,,,-,,;,., . ,

a u tocontigu ration d i a gr:-�m .
\U , 1

he L Ll c n H l l l ,·:1 1 1

�n

'

R A _ � n ci r h c A - h i r is

me t h e p rc l i x D prodded ro p e r

f(Jrm stateless a d d ress conti guratio n . T h e d ae mon us es

on-link prefix( es) provided in tl1c IV\ to con tlg u re
.hldr�.·\,1.'' h > 1' .1 1 1 i i l k l' f .l c'I.O . A l ci i'Cl.'c' .1 1' ' c. I'C.l l c ..l ,

the

ADDRESS
AUTOCONFIGU RATION
DAEMON

STATELESS
AUTOCO NFIGU RATION:
USE ON-LINK PREFIXES
AND I NTERFACE TOK E N

STAT EFUL
AUTOCONFIGU RATION:
PRO CESS CONF IGURATION
I N FO RMATION. START
DHCPV6 CLIENT

l

LOCATE
DHCPV6
S E RVER

DHCPV6

USER SPACE
-

-

-

-

"'""'ere

-

KERN E L SPACE

-l

":e 1 OCTL

ADMIN ISTER ADDRESS
CONFIGU RATION STATE
FOR THE RECEIVING
I NTERFACE

Figure 1 4
Address A u roconrigur,nion

d e l e te d , or u pd a ted 011 the i n tcrbcc based o n t h e pre 
ri :xes ,1 n d l i k ti m cs rccci ,ni i n the RA packe t .

I Pv4, w h i c h represe n ts a \ C rv l a rge i il\'esr m c n t a n d a
pote ntial pool o H Pv6 appl ications. Seco n d , t h i s A P I is
perhaps in the most wid espread usc i n the i n d ustrv ,md

Interactions with Stateful Address Configuration

\Vh e n the d J e mon rccc i \TS '1 n RA, a n d the m an aged
bit rbg is set, the host c.m u se st,nc fu l ,1d d ress c o n 
ti gur:tri o n , u s i n g D I--I c : I'\'C) . D H C P,-6 i s i m p l e m e nted
as ,l se p,lLlte

Lhenwn

process

in

our

protot\·pc .

is avai l a b le on a ,,·i d e \',l r i c t\' o f p l a t r( m n s : t h e bendits
of sta n d ardization :ti-c com pe l l i n g .
DNS AAAA Support

D :"-J S prm·i dcs suppor t fo r nnp p i ng n ,1 m e s to

IP

D I--I C : l'\6 d di n cs 'l c o m p l e te Ill'\\' m o d e l ti·om t h e

a d d resses a n d m a p p i n g I P �1 d d rcsscs h,Kk to t h e i r cor

n i s t i n g D H CI),.4 i l l l f1 l e m c n t,n ions i n the i n d ustn· to

respo n d i n g names .''' ' l' h e t\'f1e A resou rce recmd is

d\'llJill i c a l h- c o n ri g u re ,ld d resses. The usc of l i n k - local
add resses, m u l tiClst, ,1d d ress con h gu rari o n , and i n hcr
Cllt su pport r(>r dV!l,l l l l i C r e n u m b e r i n g o f h osts i n

I p,-6 ca u sed '1 lle\\' a rc h i tec t u re J n d d e s i g n i n t h e

used to h o l d an I P\'4 .1d d ress. S i n c e i ts size is ti xed

a t 4 b\·tes, a nt:\\ resou rce record n-p e , AAAA, \\ as

d di n e d to h o l d I Pv6 ,1d d resses.'- The D i g i o l LJ :--\ 1 \

J P,-6 protot\•pe i n c l udes �� \\' i d e l \ - used l l l l p l c m e il t'Hion

D H C : l'\ 6 spec i ri cn i o n . A c o m p a rison o f t h e a r c h i te c 

o f the

tural ciLmges be tween l! I--I C I'v4 a n d D I--I C : P\·6 c a n b e

D o m a i n ( B I .'! D ) , ,,·h i c h 1 1 ,1s been m od i ried

D�S k l l 0\\'11 '1s Bnke l e v

r( m nd i n the D H C : l'v6 spec i ricati o n . '

AAAA record s .

Application Services

Address Manipulation Routines

I nt e rn e t
ro

N .1 m c
s u p port

A t\'pical I P i m p l e m e ll t.ltion pro,·i d cs se\·e ra l l i hr:-� n·
M ost TC: l' ,m d U D l' 'l p p l ications can be used wi t h

rou t i n e s r()r m a n i pu b r i n g I P ,1 d d resse s . Th ese i n c l u d e

I Pv6 with rc Ln i vel y m i nor mod i ricati o n s . The pri mary

rou ti nes r()r conve rti n g ,1d d resses bcrween hi narv ,m d

issue is the h rgcr add ress s i z e , both r( > r i n t e rn J I storage

tex t u a l representations ,l l l d ro u ti n es r( J r tLl llSi:tti n g

n eeds in rhe appl i cnio n ,m d r(>r add ress tra nsre r across

n ames to a d d resses and .1ddresses to n a m e s . Ne\\' r o u 

svstcm i n terbces. I n t h i s secti o n , we review t h ese

t i n es h a d to be provi d e d t o pe rt(>rm th ese fu nctions

issues a nd others .

fo r J I'\·6 a d d resse s . 'fi le D i g i t :� ! UN I \ 1 1'' 6 prorotvpe
provi d es the

API

routi nes d escribed

I n terface E x te nsions r( > r

in

" g ,1sic Socket

I 1\·6." " '

Am· A P I c u rren th- i n use r( > r I p,-4 could be m od i ri e d
for l l'v6, b u r o n l v the BS D sockets A P I is bei n g i m·es

inetd Daemon

tig:tted wi t h i n the I ETE r( > r t\\'O reaso n s . "-'' F i rst, l a rge

The i n etd d a e m o n c reates sockets on h e h :-� l f o f a p f1 l icl

n u m be rs of a p p l i c :n ions use t h e sockets i n te r face fo r

tions, i m-ol<. i n g the a p p l i urions o n h· ,,· h e n needed a n d

Dig:itJI Tcc h n i u l ) o u m .il

] \)

pass i n g the open sockets ro them . W i th t h e a d Y e n t

o f t h e A �_ l N 1.:,T6 soc ket tvp e , i n c rd w a s mod i f-ied

to accept a new a p p l i ca ti o n u m ri gu r a ti o n option i n
i ts co n f-i gu ration t-i k . T h e kC\wmd i n c t6 i s u sed to
i n d i cate a n �1 p p l i cnion that ,,.�1 1 1 ts to

usc

A r_ I N ET6

State fu l :td d ress c o n ti g u ra r i o n ll'i l l be i m p l e m e n ted
as spec i fied in D H CPv6 �1 11d ll'i l l c o n ta i n

:1

c l i e n t, a

senu, a n d .1 rc Ll \ ' - :lge n r . This ,,·ork \\' i l l be tigh tlv cou
p l e d \\'i t h d\·namic u p d �1 tes to D N S to pnl\'idc r n C (\\·orks that USC StJtC

word ) i n d icates usc o f A r _ 1 1\ LT sockets .

l css :�d d rcss a u tocon fi gurati o n , D HC I \·6 ,,·i l l b e a\·a i l 

a b l e to configure other pmution JSSr I P v 6 . D i gita l Ius been acti\'C

m od i fied ro s u pport l P\'6 , i n c l u d i n g Te l n e t and FTP .

\\'i t h i n the I ETf \\'Orki n g grou ps t h ;n �lrL' d c ti n i n g the

These programs were mod i f-i ed t o u s c I Pv6 sockets,

ATM solutions.

a d d ress structu res, and l i b r�1 n· routi nes. N o te that the

I P\'6 now su pports rl ow i n f o r m �Hion in the I J\·6

! Pv6 sockets a l so s u pport collllll u n i c a tions <)\'er I Pv4 ,

header a nd in the I l)v6 BSD socket

so that a p p l i u tions n eed not lll a i nr ::t i n separate sockets

i n h e re nt q u a l i t\'-ofscrvicc ( QO S ) m e c h a n i s m i n ! Pv6

r()r

T Pv4 a nd ! Pv6, :ll l d a s i n g k c x cc u t:� ble i nugc c a n

t\ P l s n· u c r u r c . T h i s

meshes we l l wi th c ff-( l rts to su p p o rt reserve resources

i n tcropcratc with b o t h tvpcs o f rc lllotc systclll .

on a n c t\vork as speci fi e d in the Reso u rce Rese rvation

Future Work

n o n bmadCJst d a c1 l i n ks w i l l c ncom p<1SS �� d e s i g n cen 

Furu rc i m p l e me n tation c fr(H·ts \\'i l l i n c l u d e securi t\',

parameters

ro u r i n g ,

mod e l fo r \'i d e o - :m d :w d i o - rc b tc d �l pplications :�cross

Protoco l ( RSVP ) . ''' Usi n g RSVP over bro a d c:�st :� nd
ter that s u p ports a wide range of resou rce rcscrv�Hion
st�ncfu l

add rcss

con ri g u ra t i o n ,

dvna m i c

upd ates t o D N S , I P,·6 m·cr P P P a n d ATivl , t·csourcc
rcscn·�n i o n , �l lld scn·icc l ocation . I n add i ti o n , \\'C \\·i l l

m:� i nt a i n

a

consiste n t p c r t( mnancc

a n C t\\'Ork pr 1 P\'4,

c r:� b i l i rv C\'CIHS, ,,·b i ch is a pr:tctic:tl and concentrated

nU\' ben e fi t ri·om the grcltcr IC\'CI o f su pport r(> r h�lsic

d't-<>rr to d e b u g the specif-i cati o n s
I P \ - 6 scc u r i t\' s u p ports both the

tec h n o l ogies, such <1S scc u ri t\· a n d m u l tiust capa b i l ities.

and the cod e b:�se .

f-( .)1' these ri. mctions \\' i l l

sen·ice l o u t i o n h o l d s prom ise

r(Jr I P\·6

and

a u th e n ticati o n a n d

the cncnvtion o f H\·6 pac kets e n d - to-end .�' The mod 
ule

reside i n the knnel :� n d most

Sum mary

l i ke i l' w i l l be ca l l ed a t the p o i n t \\'here the I P,·6 nct\n>rk

D igital has designed a protot\'fX of l p, 6 o n the D igir:d

l :wcr p�Kket is processed . A kc\' n1<1n.1gc m c m fra m e 

U N I X operati n g S\'Stc m . Tec h n i q u es �md tec h n o logies
ro

work is be i n g d c,·c lopcd t o su pport b o r h a u th e n tica

ha\·c been d c,·c l o pcd

tion :� n d e n crvption . To access the kc\' m :tn:tge m c n t

I P\ 6 arc h i te c ru rc ; in p r

u n iust

ro u t i n g .

I n ad d i ti o n , c n h <1 11CCL11Ct1ts have been m a d e to l P\'4

s u pport Open S h ortest

( OSP h·6 )

and to p rm·ide m u lti 

References
l.

P. G ross ;md P. A. l m q u isr, " ! ESC Dc l i bn;Jtions on Ro u r 

ing :m d Addr�ssing," Rl C : 1 3 8 0 ( "Jo,·c m bc r 1 99 2 )

2.

S. B ra d n e r Jnd A. lvb n k i n , "The Recommend�nion
fo r the I I' Next G e n e ration

( J uly 1 9 8 2 ) .

R . H inden, " S i m p l e I n ternet Pmroco\ P l u s 'Wh i te

P a p e r , " tu:c I 7 1 0 ( October 1 994 ) .

4 . S . D ee r i n g a n d R . H i nd e n , "Inrcmet Pro toc ol , Vecsion
6 ( I.l'\ 6 ) Sp c c i ti c atio n , " RfC 1 8 8 3 ( J�nuacy 1 996 ) .

2 5 . W. Stevens and M . T ho m as, "Advanced Sackers A P I

for !Pv6,'' vVo rk i n progress ( October 1 996 ) .
26.

cast Add ress A l location," R.FC 1 8 8 7 ( j a n u a r y 1 99 6 ) .

R . Hinden a n d J . Pos t e l , " I Pv6 Tes t i ng Address
Al loc at i o n , " IU'C 1 897 ( Ja n u ary 1 996 ) .

7.

S . T h omso n cmd T. N c1 r re n , "1Pv6 Stateless Add ress
Au roconfigura tion ," RFC 1 9 7 1 ( A u g u st 1 99 6 ) .

8 . J . Bound and C . Perki n s , " Dy n a m i c Host Configura

9 . A . C o n ra a n d S . Dee ri n g , "l nrcrner Conrrol M e s s age

S u pport I P Ve rsion 6 , " RF C l 8 8 6
28.

Discoverv [()!' l P Version 6 ( l Pv6 )," RFC 1 9 70 ( August

1 99 6 )
1 1 . M . McKusick e r a \ . , The Design and implementation

o/ the 4 . 4 BSD Operulinp, 5 ) '5/elll, ( Rea d i n g , Mass . :

Addison -Wesley, I SB N : 0 - 2 0 1 - 54979 - 4 , 1 99 6 ) .
cr

a \ . , " C l ass l e s s I n t e r - D o mai n

1995).

R . Atk i nso n , "Securitv Archirccrure tor the Internet
Pro r o col , " ( Work in progress, J u ne 1 996 ) .

Fu ncti o na l

Specification,"

( Wo rk

u1

progress,

August 1 99 6 ) .
30.

J . Veizades e t a \ , Se rvi ce
.

"

Loc a ti o n P r o tocol , " ( Work

in p r ogre ss , J u n e 1 996 ) .

General References

1 0 . T. Narten, E . N o rd ma r k , a n d W . S i m p s o n , "Neigh bor

1 2 . V. Fuller

( December

2 9 . " Resource ReSerVation Protocol ( RSVP) -Version

Protocol ( l Clvl l'\·6) for r h e lnrerner P ro toc o l Ve csion

6 ( ! Pv 6 ) ," JU'C 1 88 5 (January 1 9 96 ) .

" D o ma i n N a m e s - C on ce pt s v6 Sp e c i ti cn i o n , " Work i n progress ( October 1 996 ) .
18.

K . S kl ow e r , p ri va t e com m u n i cation to lvb tt Thomas,

September 1 99 5 .
1 9.

R . G i l l i g:lll a n d E . Nordnurk, "Transition Mecha
n isms to1· ! Pv6 H osts and Ro u te rs , " lU'C 1 9 3 3 (April
1 99 6 ) .

2 0 . S . D e e r i n g <111 d R . H i n d e n , " I P Vnsion 6 Add re ss i n g
A rc h i tecture," RFC 1 8 8 4 ( J a n u a r v 1 99 6 ) .
21.

R.

G i l l i gan et a\ . , " Basic Socket I nrertace Extensions

tor I Pv6," ( Wock i n progress, A p r i l 1 996 ).
2 2 . M . C ra w ford ,

"A Method tor the Transmission of ! Pv 6

Packets over Ethernet Networks," R.FC I 97 2 ( A u gust
1 99 6 ) .

D a n i e l T. Harrington
As a principal soft w a re engi neer i n Digita l 's l Pv6 Program
Office, Dan H a rr i ng to n p a rti c i p a te d in the Digital UNIX
I Pv6 prototype effort. P ri or to th i s

the

DECnct/OSI

wo rk , he helped d eve l op

prod u c ts on the ULTRIX and t h e Digital

U N I X platforms. After j o i n i ng Digi ta l i n 1 98 2 , Dan worked

in p e rto rma n ce analysis, field support, c1nd sofTware devel
o p m e nt He reec i , ·c d a B.S. i n mathematics ri·om Rensselaer
Po l y te c hn i c l nstitur.e. Dan is currcnrlv with Lucent
.

Technologies.

Digit� I

Technical Journal

Vol. 8 No. 3

1.996

21

Matt Thomas

James P. Bound
J i m R o u n d is :1 c o n s u l ri ng; soft\\ :u·c ,· ng;i n c c r :1 1 1 d rhe re c h 

n i o l d irector tor l r\ 6 \\ i t h i n t h e 1 1'1 (> l'rog;r:Hn O ftice . ) i n 1
is rL·spo m i h l e f( >r t h e Ol n.l l l ;�,h .mccd dc l e l oj> l l l c n t ;�rc h i 

in C1 l i ti m 1 i :1 A l t hou gh h e i s :1 J>ri n c i pc1 1 soft\1 :11-c e n � i n el'l"

tec t u rc :1 n d re kr�nec A l p h :1 Dig;it:1l L1 :-\ l \ code boi s e , " h i c h

i n t h e OJ'e n \ ' ,\ ! S <; ,·ste ms S o ftll':1rc C r o u p , /vb tt Ius spcm
tile: l :1st eigln 1 c:11·s :ls :1 d e 1 · e l opcr ol · I J C t\\ orking p rod u c ts

i s :1 l so D i g i ta l 's I f: I T l l'1 6 re c l 1 1 1 i ct l lc:l d n :md o n e o t" t l1e

h i s o n go i l l ):'; i m o i H· m c n r "·i th D i g; i t .d l' :-\ I X ! 1'1 6 c t'ti ll-rs,

,-cri fi e s t h ;�t t h e 1 1',·6 S f1C C i tic:Hiom :11·c i m p l c nl c l l tol h l c . H e
l l'1 6 ad1·cmced d c 1 e l o p m c n r e n f'i l l C C I'S on A l j > h :l ) ) i g; i toll

l ' :-\ 1 \ . I n 1 99 3 , J i m lx·�:ln h i s p.l rt i c i l' " t i r m i 11 t h e I E I F
t o " ork on t h e I P n f' m
: d t h e :1d1·:u 1 ccd d e 1 e lop 1 1 1 e 1 1 t l l' n g;
p r o r o n v e . . \s :1 !ll c m hcr o i ' t h c I LT F \ l l' n � D i rccror.ltc,
J i m h e l jlL'd determine the rc q u i rcme 1 t rs :md core :t rc h i t c·c
r u n: ti>r I Png's I me rntr p ro toc ol :111d re b red fu ncrion:1lm
to s u pp or t l l' n g . T h e rc
, u l t \\";l s r i t e s e l ec t i o n o f :1 proJ>os.l l ,
110\\ K n ll\\ 1 1 cci li ca
r i o n s :md :1 C O i l r l· i ll l l t i ll):', cn1 r h o 1· tt> t h e hook ! ! 'I Ii'. /uicrucl
Protocol . \ ex! Cir·uc;-r;!/!J / 1 . H e i s

a 1 1 1 c m bcr of the I F. F. I :

a n d the I n t e rn e t SociL·n·.

John J. McCan n
):KK McC1nn is :l J >rinci J >al sotr\\·:1re c· ngineer i 1 1 the

LIN I \

F n gi n ec ri n g G roup a n d cl rn c m b e r of t h e I J',·6 projccr rcu n .
H e comri bu rcd t o t h e d es i gn :md i m p l c m e l l t:ltion of t h e

D i f'i Lll U N I \ l l'\'6 protot\'Jll: , i n c l u d i n g; ro u te r d i scmc 1·1·,

a u toco n ti g u ra t i o n , ti·agm e n t:t r i o n , re.\Ss c m bh-, p:nh MTL ·

d i scr >�-c rv, l ( >rw:lrd i ng . :md t h e I J'1·u .\ 1'1 . H e J>:1 rt i c i p:ltcs i n
sc1·cr:1l J ET F wmki n� gro u f1S .1 11d is :1 co:� u thor o f I n te r n e t

RFC l 9 1::i l , " P:nh ,vlT L; D is c muv �()!' I l' 1'C1's i o 1 1 6 . " j :tck

j o i 11 c d D i gi t:1l in 1 98 1\ to become :1 1 1 1 e m h n of the D i srri h 
Llted S1 stc rm Tec h n i c J I F1·:d u .nion C m u p . H e ,1 lso \1

or ked

in the n �: C n e r/OS I li > r OJ>c n V M S r: n g i n e cr i n g C ro u p

bctorc t:l king h i s c u rrc n r posi r i o n . H e recei1·ed :1 B .S . i n
eOlllJ1Li l e r science ( lll;lgJu c u m laude ) ti·on1 the t : n i1·crsitv
of Lo\\T I I in 1 98 8 and a n ,vt . S . i n compu ter scie nce ti·o 1n
Bosto n U n i 1·ersin· in 1 99 5 .

22

.
r\.h t r , 'h o ll l articipant i n 1·ariow, l FTl.

" · orki r 1g groups :md is :1 co:Hi thor ot'sc1 n.1l l me m c: t Dr:1tls.

I
MaA"well M. Burnet
Robert M. Sup n ik

Preserving Computing's
Past: Restoration and
Simulation

Restoration and si mulation are two tech n i q ues

The Computing Past

for preserving com puting systems of h i stori cal
i nterest. In com puter restoration, h i storical sys
tems are returned to work i n g cond ition thro u g h
repair o f broken electrical a n d mechan ical sub
systems, if necessary s u bstituting current parts
for the origi nal ones. In com puter s i m u lation,
h i storical system s are re-created as software
prog rams on current com puter systems. In each
case, the operating enviro n ment of the origi nal
system i s presented to a modern user for i nspec
tion or analysis. T h i s d i ffers with com puter con
servation, w h i c h preserves h i storical systems
i n their cu rrent state, usually one of d i s repair.
The authors argue that an und ersta n d i n g of
computi n g 's past is vital to u n derstan d i n g its
futu re, and thus that restoration, rather than
just conservation, of h istoric system s is an

The conri n u o u s i m p rm·cmc nts i n c o m p u t i n g te c h n o l 

o�· Cl usc the r;lpid ohsolcsccnu.: of' com p uter S\ ' S tr m s ,
a rc h i tectu res,

m e d i a , and dn·iccs. Since old c o m p u t

i ng S\'Stcms ;Jrc Ll rch- fK rc c i , -c d ro h ,l,·c am· , - a l uc , rhc

danger o f los i n g p o r ti o n s of the compu ting record is
si g n i tic m r . 'vVh e n a com p u t i n g a rc h i tecture bec o m es

e x ti n ct, i ts so ft\l',llT, d a ta , and ll't' i rtcn ;m d o ra l r e cord s
oti:cn d i sa ppear 'll ' i th i t .

O l d e r co m p u te r svste ms e m bodv major i m·estm c n rs

i n soti:ware, the \'J l u c o t \\'h i c h ma\' pe rs i s t long a her t h e
S\'Stems J J a,·e lost their rcclm il'

process o f restori n g a particu lar P D P - 1 1 mi n icom 
p u ter. The se co n d section d i s c u sses the s i m u l a t i o n
of old com p u ters on modern S\'Stems. 1 t d e s cri bes a
s i m u l a ti o n framework c a l l ed S I M , ll ' h ic h h:�s been
used to i m p l e m e n t s i m u la tors ri:>r the l' D P - 8 , P D P - 1 1 ,
P D P - 4/7/9/ 1 5 , :� nd No1·:1 m i n i co m p ute rs .
Restoring Old Computers
Since the com p u te r b c u m e

�•

ma ss - p rod u c e d i te m in

the late 1 960s, i ts t\'\)ic a l l ik c1 cle has consisted of i ni t i a l

i nst�1J iatio11, re ll t a l or d c p r c c i �H i o n

re te nti o n

fC>r a b o u t tJ I'C \'Cars,

and usc r(Jr a k11· more 1'c1 rs ( j u s t in c1sc ) , and
th e n retircmcllt :md J t ri p to r bc refuse d u m p . There is
o n l v J brief window of opportu n i ty to col lect o l d com
p u ters at the end ohhcir working l i k . O nce that wi n 
dow i s dosed, t h e c o m p u ters arc gone r( J re v cr.
The Australian Museum Collection

I n Syd ney, A u sr ra l i�1 , t h i s window of opportu n i ty
ti rst became �• pparellt in 1 9 7 1 , when the e a r l y P D P
s y s te ms IT :Jched t h e e n d s o f their l i re c y c l e s . D i g i ta l ' s
Austr:� l i a n s u bs i d i�1 r v bcg:1n c o l l e c t i n g svstcms b y a
c rea tive p rogr: un o r· tr:Jd e - i n s t(Jr new eq u i p m e n t . ' I t
w a s c sp c c i a l l v urge n t to o b tJ i n e x �1 m plcs of the 1 2 - bi t ,
1 8 - bi t , ;md 3 6 - b i t l' D l' s e ri e s , �•s rhev ll'cre rc l a t i l - c l y
bv in n u mb..:r. Table I l i s ts rh..: percen t�r d i ;�gnostics.

Thne is a nnwork of e n r h u si�1sts
who c:�n h e l p at this stJge .

:�

ro u n d

restore �1 1 9 60s

m ac h i ne a rc as t( J I I ml -s :

•

I nspect the h ard11·:�rc rcll·

or

t h e 11 o r l d

26

•

sak t�·, r �1 r ri c u l ;�rJ,·

\'ol . li :\n 3

Po\\ ' c r u p t h e com p u ter, checki n g s u pplv 1·oJ tagcs,
;� n d

front consok t(Jr s i g n s

ofl i k .

U s e si m p le ro u ti n es at t h e s11· i t c h register to c h e ck

1 996

Fit a s e ri a l l i n e u n i t so t h a t �1 VT

or

�1 'Te l c tvpe co n 

sole c a n b e used .
•

I 9 7 0 s l' i nta ge

the heal'\' d rJII'e rs J n d s l i d e m ec h a n i sms.

nu1· open

Assemble :1 min i ma l s 1 ·s re m o f C P U , me mon·, :m d
console swi t c h r e g i s te r �(J r l l l i tial te st s .
t:lns,

•

p h 1 ·si u l

peop l e

rl:x elcme nt�1 r\' o p e ra ti o n .

O nce the " i n gred i e n t s " h a v e been co l l ec te d , t h e

steps n e ed e d to

•

•

Co l l ec t h:1rdw�1re m:m uals ;�nd s c h e m a t i c s .

p r i n c i p a l criterion i n restora 

the back door.

:1 S \ ' S t cm

C o l lec t d i agn o sti c �1 11d opc r �H i ng software o n origi

;1

tion, since so m ed a v n o n te c h n ical

Col l e c t t h e h a r d 11·�11-c, i f p o ss i b l e two or i d c a lh·

to work on a n d a s pa re , as w el l JS the a bi l i n · to m a ke
•

Careful II' i nspect t h e po11 c r SI'Ste m , h i g h - 1 oi L1 g e
sources can ki I I . AI though most o r· the pm1 n 11 i r i n g

is n o t essemi a l . )

•

Ph, · s i ca l k assemble t h e h a rd ll'�1re, c h e c k i n g mod u l e
allocations, u b l i n g , e tc .

goocl' m es s . I t s h o u l d be re m m ed as s oon �1s possible ;

G e t t h e k e 1 · hoa rd e c h o i n g to t h e screen

11 i t h s i m p l e ro u ti n e s .

m

pri mer

I f t h e y arc ;1 1·a i L l b l c , r u n t h e i me m �1 l tests of t h e

read - o n h- m e m o n ·

( ROJ\11 ).

1

I

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}

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RX01
DUAL 8-INCH FLOPPY D I S K ETTES

TD8E TU56
ACCU M U LATOR TRANSFER
DUAL DECTAPE SYSTEM

PCBE 300 CPS READER.
50 CPS PUNCH PA PER TA P E
PDP-8/E C P U WITH EXTENDED ARITHMETIC
ELEMENT. 1 6K WORDS MEMORY.
KLBE 2400-BAUD CONSOLE.
KLBE 2400-BAUD COMMUNICATION PORT.
DECTAPE BOOTSTRAP. RK05 DISK BOOTSTRAP.

R EAL-TIME CLOCK

RK05 REMOVABLE 2.4-MB
CART R I DG E DISK

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STORAGE RACK FOR 1 0
DECTAPE SYSTEMS
H861 POWER DISTRIBUTION

F i g u re 1
P D P - .S/1'. C : o111 p u rc r SI'StL' l l l

Com e n tion:�l "·isd om \\ O u l d no\\' �Hh ise t h a t a l l t he

bi l i t i s q u es t i o n a b l e , hm,·c ,·cr, ;l nd the proced u re i s

d i a g nos t ic rou ti nes be ru n . H o"·e,-cr, d i a g n ost i cs m:re

ted io u s . M a m· d i ;1 g n ostics \\'ere 0 1 1 p ;1 pe r t;l p e , b u t

( p h i losop h i ca l ! \· ) �1 ��\ �1\'S used

ous ! \ · g oo d m a c h i n e ; they :tre

to ti n d b u gs i n a pr ev i 
too co m p l ex when h u ge

c h u n ks o f t h e rm c h i nc m i g h t sti l l be m issi n g . The

most f1 L1C ti c : d next stq1 i s to ge t m :tss stor:�ge o n - l i n e .
D e p e n d i n g on t h e m :� n u t�1 c r u r e r, t h e target device

Y

u s u a l J v the q u i c k e s t t e s t i s t o l o a d

J

co m p l e t e p;1[)Cr

S\'Stem ( such as fOCA l . t()r D i g i u l 's S\'S te m s ) I h h c

diagnostics run, the svstc m is prolx1 bh· fu nctio n a l .
Once the CPU, c o n sol e , Jnd m c morv ;lrc \Triti c d ,

ad d i t i on a l p e ri p h e r a ls c a n b e ;J dd ed , one ;H a rime . I t

111:1\' b e a t-loppy d i s k d r i 1·e , a e :� rr r i d ge h a rd d is k d ri v e ,

pays to tJke t h e ti me a n d c ft( > rr to rcsc1rch bus

rape . With a work i n g mass

a d d ressts, i n ter r u p t \'CCtors, po\\'c r s u p p l y load i ng,

or some t(m11 of m ;1 g n e r i c

storage device a n d �1 boo t s t r a p rou tine, it beco mes
poss i b l e
or

to hoot a si m p l e operating system ( l i ke OS/8

RT- 1 1 t( JI' D i gi t a l ' s svsre m s ) . This q u i dd v sh ows

whet h e r t h e m ac h i n e is \\' or k i n g or not.

I f �1 mass storage de,·ice is nor :w:�i b blc , t h e next best

t h i n g i s papn t:�pc. T h i s

C1I l

be e i t h e r the S\'Stem's

LlC k - m o u ntcd IT;1 d e r ;md p u n c h o r the paper t a pe
rc1dcr on

:111

AS R 3 3

or

ASR3 5 co ns o l e . The re l i a -

and mod u le pbce m e n t, and to ke e p

:1

l o g book \\'ith

con ti g ur at i o n d i a gr a m s :�nd resu l t s . ! 1 1 gene ra l , if t h e
conti g u ration rules a re t(> l l owed , t h e i te m s \\' i l l w or k .
T here arc Jl:w e l e c t ron i c tJ i l u res, e\·cn i n 2 0 -

or

30-

ycar- o l d mod u l es . ·when �1 J1ro b l c m ;1 rises, i t is u s u al h
add ress \'ector stra ppi n g, p lws i u l d a m ;1gc,

or

m i ss i n g

cables. Corrosion of bo;lrd contacts c a n be :1 prob l e m ;
thev s h ou l d be d cm c d \\' i t h

Digiral Tcc h n ic J I j o u m ;ll

:1

c l c :� n c l ot h

or

G l rd board

\'o l . � '-:o 3

l '>96

27

Table 3

Ta ble 4

Goa l s of t h e Austra l i a n D i g i t a l M us e u m

D i g it a l Data M e d i a from 1 9 60 to 1 99 6

To preserve o n e of each m o d e l of D i g i t a l 's com puters

P a p e r t a pe

To keep each major D i g it a l o p e ra t i n g system wo r k i n g

80-co l u m n p u n c h ed a nd m a r k sense c a rd s

To h ave a work i n g u n it o f e a c h D i g i t a l term i n a l , con

7-track, h a lf-inch m a g n e t i c t a p e

s o l e, and PC

9-track, h a l f- i n c h m a g n e t i c t a p e

To prov i d e convers i o n a n d a r c h i v a l f a c i l i t i es for o l d
media
To p reserve s i g n i f i c a n t D i g i t a l l itera t u re a n d m a n u a l s
To prese rve a VAX - 1 1 /780 comp uter a s t h e o r i g i n a l
u n it o f 1 V U P
To d i sse m i nate i nstruct i ve a n d e d u cat i o n a l m ate r i a l

D E Ct a p e a n d LI N Ct a p e syste m s
A u d i ocassette
D E Cta p e II c a rt r i d g e (TU 58)
Com pacTa p e (T K 5 0, etc . )
Q u a rter- i n c h ca rt r i d g e t a p e
D i g it a l a u d i o t a p e

To e d ucate a n d a m use o u r sta ff, o u r custo m e rs, a n d
the public

8- i n c h f l oppy d i sk

To s u p p o rt t h e D E C U S N O P (nost a l g i c obsol ete prod
uct) S p e c i a l i n te rest G ro u p

3 . 5 - i nc h floppy d is k

To p reserve spa res, too l s, test g e a r, a n d docu m e n t a 

R K 0 5 r e mova b l e d i sk

t i o n to k e e p t h e c o l l ect i o n work i n g

5 . 2 5- i n c h f l o p py d i s k

R K06, RK07 remova b l e d i s k

To prese rve a nd protect these treasures f o r fut u re
g e n erat i o n s

R L0 1 , R L02 rem ova b l e d i s k
R P 0 1 . . . R P06 remova b l e d i s k
R M 03, R M 0 5 remova b l e d i sk
RC25 remova b l e d i s k

( for example, a busi ness urd ) , not \\'ith a pencil cr�1scr,
\\'hich l ewes resid ues. S i l icon components appca1· to
be \'Cl'\' stable and a tri b u te to the conscn·ati\'C d esign
pri nciples of carlv computer engineers.
The main components that scCill to age �li'C power
supplv capacitors, bns, and l igh ts . The fi l ter capaci 
tors across the high-voltage sou rces can short, and
reference electrolytic capaci tors in power supplv regu
lators can dry o u t . Although the large c1pacitors in
power supply RC fi l te rs have prc)\'cn to be reliable,
some restorers replace them as a m atter of course r(>r
sarctv reasons. Sm Expniencc
p roves that tl1ey arc . A classic PDP-8 system restored
in 1 9 8 8 still turns on happily ( u n touched ) eight years
l a ter. A fu l ly c on fi g ure d P D P- 8 / E system is sti ll work
i ng tour years after restoration .
Restoring a Minicomputer: A Case Study

An o n go ing project is the restoration of a large,
U N I B US - based P D P- 1 1 system with many U N I B U S
perip herals attached to i t . The project was started
us ing the origi n a l P D P- 1 1 /20 CPU. S i nce many
P D P- 1 1 peripherals were d esigned long �1h-cr the
P D P - 1 1 /2 0 C P U , it could not cope with single- board
d i rect memory access ( DMA) d evices, mct:d-oxidc

28

Digit:�l Technical j o u rn a l

Vol . 8 :--: o . 3

! 996

semicond uctor ( MO S ) m c morv, and other l ater in\·e n 
tion s . T h e project rd(>cuscd on t h e 1J1id- r�ngc
I' D P- 1 1 /3 4 , \\ hich in retrospect h �1s prm cd \\ isc. The
P D l' - 1 1 / 3 4 su pports MOS mcmorv, h as an LED and
p u s h - b u tton consol e , and represe n ts a mature i m p l e 
mentation of the P D P - 1 1 i nstruction s e t . I t h as a n
optional cac he, battCI'\' bac kup, rl o�l ting-point op era 
tion, �111d the extended i nstruction set ( E IS ) .
The cmrcllt conriguration occ upies three large c:Jb
i ncts in \\·h:n used ro be the d in i ng room or· Max
B ur n et's house. The \'irtucs of the U N I B U S �11-c m:my;
i n parricu lar, i t J l lows mod u b r connection of l/0
dC\·iccs and other componcms. H m\'e\'Cr, 1/0 d evices
of the e ra ofte n we igh 1 0 0 pounds and :�re mounted in
1 0 - i nc h d rawers; their s heer p hysical size and weight
arc disi ncent ives to reconrigu r:n io n .
The project c u rrenrly u ses rhc RT- 1 1 operating
system bcu usc of i ts simpl icity and extensive device
d rivers . Evc n t ual lv, it may be poss i b le to r u n the
RS X - 1 1 M �111d the RSTS/E syste m s , but there is l i trl c
to gain h·om a media conversion poin t of view, beca use
l\T- 1 1 includes u ti l i tie s tor d ea li n g with r(>rcign fi l e
t(mnats .
The nuin d i Hi c u l tics cncou ntcn:d h:wc been associ
ated with the power supply: the DC l ow sigml threads
i ts way thro u gh even' periphera l . The �1 bscnce of
U N I B U S gra n t comi n u i ty cJrd s can c reate h a\·oc.
Since this P D P - 1 1 system is very L l rge , it is stra i n i n g
the design ru les conccming r1 oating \'Cctors , cu rre n t
load ing, and bus l oads .

The C : l ' U � n d mc: mon·
. to check
. caS\'
. arc re l a t i 1 c l1·
ou t . D ue to the ,·c rsa t i l i ry of t h e U N IB US, holl'ever,
checking

out

the

1/0 S\'Stcm i s ,·en· labor i o u s .
Starti ng ,,· i t h programmed 1/0 te sts works best, tol 
lo11ni lw i nt e r r u pt tests, a n d ri na l l v DMA or non 
processor rch:rcnce ( N PR) tests. Ex p eri e n ce s hows
that rests need to be: re r u n whe never  l loll'ing:
•

proposed d es i gn . For e x a m p l e , prior to ta bricari o n ,
a l l modern m icroprocessors a re extensively s i m u 
la te d , fi rst a s a bstract p c rtcmn a nce mod e l s a n d then

CR1 1 p u n c h ed card read e r

a t i n c reasing levels of deta i l .
•

r u n i n h i g h l y constra i n e d envi ronments s u c h as
e m b edded systems. S i m u l  r program d e b u ggi ng, i t

becomes a usefu l rooJ for d e b u gging programs t h a t

rhcv all'air i nsta l l ation r ime a n d cft(>rt:

goa l

'

D e buggi n g r()r embedded syste ms.
tor contains

Although the to l loll'i n g peri p h e ra l s arc al'<1i 1 J b l c ,

eve n t u a l

Design of n ell' S\'Stem s . The sim u l ator m i m ics t h e
beha1·ior of a fu t u re chip or com p u te r S\'Stem a n d i s

PC 1 1 p :� pe r t:�pc read er a n d pu nch

The

provide more e l a borate f:1 c i l i ties to su pport

pertormance i nstru mentation or debugging.

Seri al line u n i ts tor conso l e a n d seri a l p ri n te r

•

•

l/0 completion, t(>r

wa1· to sched u l e events, s u c h as

later c\·a l uari o n . It c:�n :�!so i m p l e m e n t other time

used to understa n d :� n d d e b u g t h e beha1·ior o f the

•
•

tations of ad1·a ncing ri m e, s u c h a s t h e n u m ber o f

well as basic control comma nds s u c h as start and stop.

is r s tra i g h tto r wa rd repl ication or

l as t grea t

a l most e ver y

p l ayback of com pl icated seq u e nces, r e m ovi ng the

Ti me w i l l te l l .

ra ctor t h a t o ften plagues the d e b u g 

randomn ess

gi ng of asy n c h ronous software on real syste m s .

Simulating O l d Com puters
•

Preserl'ation of past sof t w a re . S i m u lators can pro

A si m u l a tor is a com p u t er progr:1 m o pc r:ni ng o n o n e
c o m p u te r s1·srem ( k11011 n as the h os t S\'Ste m ) ll' h i c h

vid e m i gration assistance in rbe transition fi·om older

m i m i cs t h e be h a ,·ior of a n o t h e r c o m p u ter S\'Stem

systems hal'c prm·ided simu lators tor older arch i 

( k no11 1 1 ;ls the t:1rgct svsre m ) . The s i m u l a tor's d at :l is
th e state of

rbe target c o m p u te r syste m - registers,

to ne"'er architectures. Manv tra n sitional computer
tectures, t y pi c 1 1 l v at the m i c rocode lel·e l , r o assist

c u sto mers r d ecod i ng

i n structions i n si m u l ated m c m on· and p er r( m n ing the
sp cc i ri ed :� I t e rations of sim u l :1ted m ac h i n e sta te . Th e
ex ec u t ion e n gi n e keeps track of s i m u l ated time in a rbi 
tr:ll'\' u n its, ll'h ich n1av be precise representations of the

fe r ln e l

.len: I s o f si m u lation are register tr;lns
( RTL) , i nstructi o n , and software speciti c .

An RTL si m u b tor atte m p ts t o m i m i c t h e major

h a rdware blocks of the target S\'Stem and to i m pl e 
ment i ts actual l og ic e q u ations. The goal i s absol u te
Di[; ir�l Tec h nic� I )ot tl'll,li

Vol . 8 No. 3

! 9 96

2\J

tid c l i ty, the test o f ll' h i c h is t h a t 110 11 iccc o f softll'�l rL·

General Design Considerations The d esign of Jn

r u n n i ng on the s i m u l a to r s h o u l d bch l l o11·s

processor- mcmon· s11 i t c h

( PMS )

Ne11·cll a n d

implc

t h e a c tu a l accc l cr;H i o n c u n·c o f <1 ] ) 1-: C :ra 11e srm:�gc

s r r u c t l l rc proposed lw B e l l a n d

s1·stc m ) and access to impkmcn ta tion d o c u 1 n c m�1 tion

m e med i n M I M I C :t n d cou n tless other s i m u b rors
:1

t h Cus on the i n te n t i o n s o f rhc

t i o n . The ,11 <1 i b b l c co m m a n d s i n

arc h i tecture spcc i tic:�tio n . As <1 res u l t , i n struction s i m 

Ta b l e S .

F i n a l il·,

a

sofu,·arc-spccitic

needed lw most s i m u i ;Hors, s u c l 1 as e1·cm q u e ue m a i n 

s i m u btion

ti 1 r thcr

a bstracts rht: ti.1 ncrions o f the target s1·srcm to on I I · those
needed

L11'

J par ticular piece of t:�rgct s1·srcm soful' 3

l l! %

Table 5
C o m m a n d s Ava i l a b l e i n S I M

Com mand

Def i n ition

attach < u n it> 

Assoc i a t e f i l e with u n it's m e d i a .

detach < u n it> I A L L

D i sassociate u n it's (a l l u n its) m e d i a from a ny f i l e .

reset < d e v i ce> I A L L

Reset d ev i c e (a l l d ev i ces).

l o a d 

Load b i n a ry p ro g ra m from f i l e .

boot < u n it>

Reset a l l d ev i ces a n d bootstra p from u n i t .

r u n { < n ew PC>}

Reset a l l d ev i ces and res u m e exec u t i o n at the cu rrent PC {or n ew PC}.

g o {}

R e s u m e exec u t i o n at the cu rrent PC { o r n ew PC}.

cont

R e s u m e exec u t i o n at the c u r r e n t PC.

step {}

Execute one i n struct i o n {or n u m b e r i n struct i ons}.

exa m i n e < l ist>

D i s p l ay co ntents of l i st of m e m o ry l oc a t i o n s or reg i sters.

iexa m i n e < l ist>

D i s p l a y co nte nts of l i st of m e m o ry l ocat i o ns o r reg i sters a n d a l low i ntera ctive
m o d if i c at i o n .

d e posit < l ist> 

Store va l u e i n l i st of m e m o ry l ocat i o ns or reg i sters.

i d e posit < l i st>

I nteractively m o d ify l i st of m e m o ry locat i o n s o r reg i sters.

save 

Save s i m u l a tor state in fi l e .

restore 

Restore s i m u l at o r state from f i l e .

s h ow q u e u e

D i s p l ay t h e s i m u l ator's event q u e u e .

s h ow co n f i g u ra t i o n

D i s p l ay t h e s i m u l ator's co n f i g u r a t i o n .

s h ow t i m e

D i s p l ay t h e s i m u l ated t i m e c o u n t e r.

s h ow 

S h ow d e v i ce's conf i g u ra t i o n o p t i o n s .

s e t  

S e t a d ev i c e co n f i g u ra t i o n o pt i o n .

help

D i s p l ay a terse h e l p message.

exit I q u it I bye

Leave the s i m u lator.

e a r l i e r. Llsrl1·, t h e marcri.1l is l i k c l \' to be contrJd i c tory,

•

Design doc u m e n ts . For S\'Stems that do not hJI'C
I'Cl'\' b rge - sc a l c i mcgration ( V LS I ) , rile o n lv c x ra n r

c m h o d 1 · i n g d i frc r i n g I"C\ is ions or 1nsions o f the a rc h i 
r c c tu i"C , <1S 11 c l l as e rrors r h a r ha1-c n c p t i n d u ri n g t he

de s i gn d ocume nts arc the l ogi c pri nts and t h e bi nr a pJ rtic u l a r su bs\'stem, such as

m a i mc n :mcc - l cvcl katmes a n d other ti ne poi nts.

Folklore . D u r i n g t h e usefu l l i fe t i m e o f <1 S\'Ste m , i ts

target system becomes obsolete .
•

Prior i mp l e mentati ons . Prior s i m u l ator i m p l e m e n ta 
tions c a n p n)\'id c usefu l i n formatio n , b u r i t must be
used c a utious l y. U n less the prior i m p l c m c n t l klorc, an d most working

svsterns a r c in t he
The I mc rn c t pbys

<1

hands

of i n d i vid u a l col lectors .

vital role in l oc a t i n g m a t e r i a l h e l d

bv e n t h u si a s ts , t hro u g h nc\\·s conferences such as
alt. t r h i sto ric wstc ms resides on pa p e r t a p e s ,
DECta p c storage systems, 2 00/5 56/800 b i ts - per
i n ch m ag n e t i c Llpcs, d i sk ca r t ri d ges, 8 -i nc h tloppy
d i sks , and so on. Few i f any modern systems h a ve t h e se
p e r i p h e ra l s; :md tew if any h i stor i c systems have m o d 
e rn n e twork i nt e rc on n e cts . T h u s , m e d i a transl ation
usually enta i l s l i n ki n g a wo r k i n g version of the ta rge t
system to a modern system b y m e a n s o f a s e r i a l l i n e .
KE RNI I T o r some o th e r s i m p le pr o toco l al lows f(J r a
by t e - by - by te network copy trom the or ig i n a l med ia to
a fi l e on a mod e rn s yste m .
Once the soti:warc has been located and moved

t h e n e x t i ss u e is s o u rce s . vV i t h o u t sou rces ,
J n d other test progrJ ms arc useless;
d e t ec t e d errors c a n n o t b e traced back to causes wi t h 
o u t m a n u a l d e c od e of the bi n a ry progra m . T h e
abse n ce of sources \\'as a pri n c i p a l reason for i n c l u d i n g
to a ti l e ,

d i ag n ost ics

sym bol i c d is:�sse m blv a n d i n p u t i n S I M .

The fi n a l i ssu e in so ftw<1 rc is licensing. Even though
the target systems a rc obsolete and often no longer
m a n u b.ctu red , t h e opera ti n g S\'Stcm soti:wJIT m a y be
prot e c t ed bv c o pyri ghts a n d l i ce nses. Most P O P- 8
soft w a re i s i n t h e pu b l i c d om:�in; however, t h e P D P - 1 1
a n d NO\·a ope ra t i n g systems J re sti l l l i c e n se d , as arc
a l l v e r s i on s of
N I X . C or p o ra te l i c en si n g p o l i ci e s
rarelv accom mod:1te h o b h,·ists; t h i s l i m i ts o p c L H i n g
s y s t e m d i stri b ut i o n to le g i ri m Jtc ( t hJt is, b u s i n ess )
u s ers . Table 7 l is ts the soti:warc tcJLmd tc1r eac h si m u l a 
tor i n S I M .

Debug T h e d e bu g p a t h tc) r a s i m u l ator d e p end s
on the ;wa i l a b l c softwa re . I d e a l ly,

the s i m u b ro r \\'O u l d
with t h e s a m e soti:ware tests u sed
ro debug t h e target h : m.l\\'arc, but this so ft w a r e is
rare l y archive d . D i agnostics c a n p ro v i d e l ow- leve l
b e d e b u gg e d

ch ecki n g , b u t diagnostics typica l l y c h e c k t(J r broken
p a rts

i m p l e m e n t a t i o n , rather than a n
i m p l e m e n t a t i o n . Even w h e n d i a gnostics
d o c h e c k a rc h i t e c t u re rather t h a n i m p l e m e n tation ( as
i n t h e b as i c i ns tru c t i o n d i ag n os t ic s on rhc PD P - 1 1
syste m ) , the a bsence o f sources l i m i ts t h e i r u r i l i t \'.
C o nse q u e n t l y, the s i m u l a tors were d e b u g ge d m o s t l y
with s i m p l e hand tests a n d t h e n w i t h r h c op c r H
: i ng
syst e ms .
Opera t i n g systems a re both e x ac ti n g <1 1ld i m pr e c is e
tests of i mple m e n ta ti o n c o r r e c tn es s . U nless  l klorc, debugged some of the subtlest problems, c rc



worl d w i d e com m u n i n·
o f historic m a c h i ne h o b b ,. · i s ts
.
a n d c mhusiJsts.

;1tcd t h e Ma kctilc, a n d provided the fi rst and most

Ben

Thomas

th e character- by-character I/0

ro u ti nes

fi-c q u c n t h·
prm idcd

used

distribmion

site .

fix VMS . C h ri s Su ddick helped debug the PDP- I I

floa t i n g - p o i n t code. Warren Toomey and the e n t h u s i 
asts Jt P U I'S ( the P D P U N l X Prese rvation Society )

i n A ustr:l i i a a l l owed me a cc e ss to t h ei r archive o f e ar l y
UNIX

rek:ascs .

the P D P- I

Lcc n d c r t

U N I X V6, and

Van

l s i m u l ator with

Doorn

References and Notes
I.

As Jll�\11�1ging d i rector of D i gi ta l 's A u srr�1 l i a n S I J hs J d i�1n·

2.

M . B m nct, "An U pdate on

debu gged

initiJ! i m pcrus to the p ro j ec t and K e n H a rrc n s r c i n
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Digital k c i l n ic.il ) o l l rn ,l l

Vol .

t; No . .i

l 'J'J6

.i 7

B iograph ies

Maxwell M . Burnet

1vl a x B u rn e t has been with D igital i n Austra l i a �or 29 yc;Jrs.

D u r i n g that time, he h:1s sol d , serviced, or marketed ;J I I t h e
m a c h i n es i n the co l l ection . H e m a n aged t h e D i g i t;l l
i\ ustra l i a s u bsid iJrv �ix se1·e n l'c:lrs. He 11 as

a

s a l esin:lJJ

;m JBM
1 6 2 0 a t Tufts Unin:rsitY 11·ith c l PDP- I 0 . H r is c u r rc mll·

in Boston durin g 1 9 7 1 :1 n d m a naged to rcpbce

the o l dest sun·i1·ing " n.:chie" i n the S vd n e y oftin: and
m;lkcs num• corpor:1re prescncnions in Austr:Jii;L H e
m a nJgcs the A u s tra l ia n D EC US Society, t h e S u bs i d i a r y 's
l cK a l content a n d e xporr o b l igations with the Austr:J\i;ln
Go1·emmenr, and the local Prod uct Assurance G r o u p .
He h : 1 s co.l l ected a m u seum o f e a r l v Digi tal machi nes a n d

is kno11 11 a m u n d S v d n c v as " M u s e u m 1\ll a x . " He recci1·cd

:1

R .Sc. ( h onours ) from M e l bo u r n e U n i 1·ersin·.

Robert M. Supnik

Bob S u pn i k has bem with D i g i ta l i n the U ni ted States

�(>r 1 9 years. H e j o i ned the 1\lbss Sro1·age Group and then
m oved i nt o Semicond uctor Engineering, where h e succes
sively Imnaged the !Jst PDI'- l l i m plementation ( th e ) - l l ) ,
Adv;lnccd De1-clopment, the tirst singl e - c h i p VAX i mple
m c l lt 

processor G rou p . H e ;1 \ so IITote or contri bmed to the
m i crocode of e1·er1' s i n gl e - c h i p VAX m icroprocessor. I n
1 9 8 8 , h e started t h e Alpha progra m , w h i c h h c ma n;l!J,Cd
t h ro u g h b u n c h of the �i rst products in 1 992 . He t h L· n
b e c a m e tech n ic 1 l d i rector, tlrst of Engineeri n g � n d t h e n
of the C o m p u te r Systems D i v i s i o n . I n 1 99 6 , h e bec1mc
vice presi d e n t of Rcsc1rch and Advanced D e v e l opme n t .

He h:1s B . A . degrees i n math e matics a n d i n h i srot·y ti-om
M IT, ;llld � n M .A . in historv ti·om B randeis U n i 1·ersi ty.

3R

Dig:ital Tcch nic.ll j o u m;ll

Vol. 8 No. 3

1 996

I

Willi am N.

Celmaster

Modern For tran
Revived as the
language of Scientific
Parallel Computing
New features of Fortran are changing the way

A Brief History of Fortran

i n wh ich scientists are writing and maintain i n g
large analytic codes. Further, a number o f these
new features make it easier for com p i lers to
generate hig h ly optim ized architecture-specific
codes. Among the most exciting kinds of
architecture-specific optimizations are those
having to do with parallelism. This paper
describes Fortran 90 and the standard ized
language extensions for both shared-memory
and distributed-memory parallelism. I n par
ticular, three case studies are examined, show
ing how the distributed-memory extension s
(Hig h Performance Fortran) are used both for
data parallel algorithms and for single-prog ram
multiple-data algorith m s .

The Fortran ( fO Rm u l a TRANslating) compute r b n 

begun by John
1 9 54. The g o a l o f t h i s project \\'JS to

guage \\'aS the resu l t o f J project
Backus at 113 M i n

provide J "'ay ti.>r programmers to express mJthemJti 
cal torm u l as through a t(xnd ism that computers could
tra nsl a te i n to m a c h i n e i n structions. I n i tially there w:ts
a

great d e a l of skepticism Jbout the efficKy of s u c h

a schem e . " H ow," the scientists as ked , "wo u l d :tnyone
be a b l e to tolerate the i n dti cicncies that wo u l d res u l t
from compiled cod e > " B u t , as i t t u rned o u t , the ti rst
compil e rs we re s u rprisi n gly good , and progra m m e rs
were a b l e , fo r t h e f-i rst rime, to express mJthematics i n
a higb- le\'el compu ter langu age.
Fortran has e\·ol ved cominuall\' over t h e years in
response to the needs of users , parricularh· i n rbe are:ts
o f mathematical o p ressi\'i ty, program mainta i n :t bi l i t\',
h ard\\'are comrol ( s u c h as I/0 ) , a n d , of c o u rse, code
opti m i zations. I n the m e a n ti m e , other l a nguages s u c h
as C a n d C + + h a v e been d esigned to better m e e t the
n o n ma thematical aspects o f soft\va re d esign , such JS
graph ical in terraces a n d complex logical l ayou ts . These
l a n guages have caught o n a nd have gra d u a l l y begun to
erode tbe scien tific/e n gi n eering Fortran code base.
By the

1 980s, pronounceme nts of the "death of

Fortra n " prompted la ngu age d esigners to propose

exte nsions ro Fortr:tn t h a t \\ O u l d i n corporate the best
fea tu res of other h i g h - b·d Llnguages a n d , in :tdd ition,
p ro\·ide ne\\' b·c l s o h n a t h e matical exprcssi\·it\' pop u 
l a r o n supncom p u ters s u c h a s t h e C YB E R 2 0 5 and the
CR.AY S\'Stems. This l angu age became sta n d a rd i zed as
Fortran

90 ( I SO/I EC 1 5 39: 1 99 1 ; ANSI X 3 . 1 98 l 992 ) . A t t h e prese n t t i m e , Fortran 9 5 , w h i c h
i n c l u d e s m a n y of t h e para l lclization features o f H i g h
Performance Fortran d iscussed later i n this paper, is i n

t h e tl nal stages o f standardi zation . It i s n o r yet clear
w hether the mod e rn i zation of Fortran c a n , of i tsc l t�
stem the C tid e . However, I \vi i i demonstrate in this
paper that modem FortrJn is a via ble ma instre a m l a n 
g u age tl lowing code ti·a g m c n t i l l u strates the s i m p l i c 
i ty of d y n a m i c m e mory ;t l locttion w i t h Fortran 9 0 . Ir
a l s o i n c l udes some o ft h c new syntax tor d e cla r i n g l'ari
a b lcs, some examples of ;trrav m a n i p u l :ttions , :tnd :t n
c x �t m pk o f h oll' to usc t h e nc11· i n t r i n s i c m :trrix m u l ri 
p l i et t i o n fu nctio n . J n a d d i t i o n , t h e exc lamation m:t rk,
1\·hicb is used to begi n commcm Str manipul:t.ting �m·a ys. ' I n acidirion,
FortLtn 9 0 i ncorporates m o d e rn c on t ro l constructs
and u p - ro -datc fcJturcs fi:Jr d ata a bstr.tction �tn d d�tt:t
hidi ng. Some o f t h e s e constr u c ts , ti: >r o:�t m ple, n o
W H I LE , �tl though not part of F O RT R A N 7 7 , arc
a l rcach· p a r t of t h e d e F:Kro forrr�m sra mbrd as pro
,·idcd , ri: >r e x a m p l e , 11 ith D E C fortLlll .
Among the kcv nell' features o f Fortran 9 0 �tre the
ti. > l loll i ng:
•

•

•

Perm issi hi l i tv of frec-ti:)rm source cod e , so pm
grammers em usc l o n g ( i . e . , mc.m ingfu l ) v:t r i J h l e
n�t mcs �t nd a r c n o t restricted to begin statements
in col u m n 7
Mod e m control str u c tu res l i k e CASE
progra m m i n g

c::u t

constructs

Extended control of n umeric

rccru rc

take

�tnd D O
ad1·�tt1tagc of

i n d c pc n dence

processi ng extensions, ti:.>r more c.tsi l y express
ing a rray opera tions and al so fo r e x p re ss i n g i n d e 
pendence ot' c l c m c n t operations

Poi mer�, t( J r more flexible control oflLtta p LK e m e n r

•

D�t t�t structures, ti:Jr d a ta absrr:tcrion

•

Usn-ddi ncd
:tbsrr�tction

tvpes

and

oper�ttors,

Proced u res a n d m o d u l e s , to

rc> r

d at�t

h elp progr.t m mns

ll'rire reusable code
•

Stream

•

Nc"'

character-oriented i n p u t/ouqJ u t te�ttures

i mrin�ic

ti.t ncrions

'vVi th these new k arurcs, a mod e rn bortLl l l p ro 
gr�t m me r c a n nor o n l y su ccessfu l l y c o m p il e �tn d c x c 
c u re prel' i o u s st:tndard s - c o m p l i a nt Forrr�t n codes b u t
also design better codes with
•

Dram�ttical lv simpli fied

11'<1\'S

of doing d 1 ' n�1 m i c

mem orl' m:t n age m e n t

•

•

40

j ) , · n r sintpliticd progra m m i ng b u t :t lso
l u r d 11 �t rc-spccitic o p t i m i z a tio n s .
i n Fortr�tll 9 0 , o n e c a n ll'rite t h e �t rr:tl'

bette r

exa m ple ,

asstgn men t
=

B

+

C

ll'hich in

AtTJI'

•

•

R EA L*8

A

precision, for arc h i 

D I ME N S I O N ( : , : , : ) ,

ALLOCATABLE

of a l l of f O RT RA N 7 7 , so users can
co m p i l e their F O RTRA. N 77 codes without
nH > d i tiu rion

srrucrmcd

•

REAL,
&

I ncl usion

W H l L E , so progr.mt mers
•

a n C :\ tc n s i o n to l- O in 1\.'\;-.,J 7 7 .

rO R.TRJ\ N 77 II O U i d

D0

1 00
DO

200
1 00

END
END

J

=

1 ,N

200

I

=

be ll'rittcn

as

1 ,M

DO

DO

The Fortran 9 0 �t rLtl' :tssig;tJll1Cllt 110t o n lv i s more
elegant b u t �tlso permits the co m p i l e r to easih· recog
n ize that the i ndi,·idu�t l dement �1ssignmcnrs arc I I H . k 
p cn d e n t of one �mother. I f rhc compi ler 11·ere targctin�
a \'ector or p �t r�t l l e l computer, i t c o u l d generate code
that e x p l oi ts the .t rcltitcctmc [)I' ta king ad 1·anragc of
this inckpcndencc bcrii'CC!t i ter;ttions.
Of course , the p:trti c u l a r DO l oop s h oll'n :t bo1·e is
s i m p l e e n o u g h tlt�tt m;tnv compi lers would recogn ize
rhc i n d ependence of i terations and could the rdi: > rc
pert(mn the �� rch i recru rc-spcc i flc opti m i zations with
o u t the aid or· Fortran 90's n ell' atT r m a nce Fortr r the progr:t m m e r to optimize d a tJ loca l i t\·. I n
l c i l s m , :md n 1 :1 n \· d a t:� 11 laecment d i rccti,·es arc pro

add ition ,

H l'F i nc l u des \\':1\'S to spec i �·

srv lc o f s i n g l e - progr:1 m -m u l t i p l e - d a ta

a

more ge n er a l

(SPM D )

exec u 

tion i n 11· h i c h scp:1 rarc processors can i n dependen tly

work on d i Hi.: rc m [1<\ rtS of the cod e . This SPMD spcci
ti u rion is t( m n a l i zed in such a way a s to make the
re s u l ring code

br

Cm H P F C.F

t h e Sr

systems of a code c a l led , t()r C\ <1 l l1 p l c , dd . f,

u s i n g rhe command l i n e
kf90

-f kapa rgs= ' - co nc '

cfd . f

-o

cfd. exe

l l lo\\' i n g s h O\\'S hO\\'

a

a n d the H P F spc c i tication h a s l o ts of ,,·a rn i n gs about

seg m e n t bcl o\\' i s so s i m ple t h a t the compi l e r cJn J u to

constr u c t . S o r par:t l lcl execution of \'J rious thre ;t d s
of con trol . The C<1 11 on ic:t l e \ a m plc is a

be i n c l uded i n the cod e . ( A ctu:l l h-, the code

par;1 1 l c l izc a l oo p .

The tr:l d i tion


41

Cluster Fortran Parallelism

1 HPF$

D I STR IBUTE

! HPF$

ALIGN
R EAL*8

X ( B LO C K l

W I TH

Y

X

X ( 1 000 l ,

Y ( 1 00 0 )

H igh Performance Fortran V l . l is cu rrc n tl \ ' the o n lv
language st�1nd ard for d isrri butcd - mc mon· para l l d
com p u ti n g . T h e most s igniticm r \\'JY i n ll' h i c h H P F
extends Fortran 90 is t h ro ugh a rich b m i l\' of d a ta

place m e n t d i re ctives. There arc ;llso l i b ra r y rou ti n es
and some extensions for con trol p:lr:JIIclism . H P F

is the s i m p lest way ofpara l lelizing d ata-para l l el ;lppli 
cuions on c l usters ( also known as " b nns " ) of work
s t : Hi o n s

and se r ve rs.

Other

m ethods

of c l uster

pa ra l l el ism , such as message p a s s ing, req u i re more

bookkeeping and a rc there fore less ClS\' to e xpress and

less cls\· to m a i n t:�i n . In :.�ddition, dming the past \'Car,
H Pl-' h;� s become ll'idely ava i l a ble :t nd is s u p ported on

the pLnfcmns of all m aj o r v e ndors .
H P F i s often considered t o b e

;1

dolo

JHtm!!c! l :m 

gu;lge . That i s , i t fac i l i tates p a r a l l e l iz :Hion of a rray
bas:d a l gori th ms i n which the instruction stre a m can
be d escribed as a seq u e n ce o f array m a n i p u l a ti o n s ,
c:�ch ohv h i c h is i n h e rentl y pa ra l l e l . What is l ess we l l

known is t h a t H P F a l s o p rovi d es a powe r fu l wJ y of

expressi ng the more ge neral S PM D p a ral l e l i s m m e n 

tioned c:1rlier. This ki n d ofpat·allc l i s m , often expressed
with mc s s:� gc - p a ssing li braries s u c h Js t\tl l' l ,' is one i n
whi c h i nd i v i d u a l processors c a n oper;ue s i m u l ra n c 
o u s l v on i nd e p e n d e n t i nstru ction strea m s :1nd gcner
:tl l v

� x c h a n ge data either b\' e x p l i c i t!\' s h a ri n g m c morv

Y ( Z : 99 9 l


X ( 1 : 998)

+

X ( 3 : 1 00 0 )

-

2

*

X ( 2 : 99 9 )

a n s wer>

END

The H Pr compiler is responsible f()r generating a l l of
the bound:trv-elemem comtmmication code . The com
:
piler is also , csponsiblc f(>r d e termini n g tl1C most C\'en
d isrribmion of ;HT�lvs.

( I t� f(lr e x a m ple, there were 1 3

processors, some chu n ks \\'Ou l d be bigger than others . )

This s i m p l e example is useful nor o n l y as ;l n i l lustra
tion of the po\\'er of H PF hut a lso as a way of pointing
to one of the h ur
proccssor system , e:t c h processor wou ld operate on
250 cle ments with

750 floati ng-point opera t i o n s. ln

a d d i t i o n , each processor wou l d be req u i red to com
m u n icate one word of dJta f(x each o f the two c h u n k
bouncbric s . The ti m e th;lt eac h of these c o m m u n iu
rions takes is k n m\·n as the com m u nications l a tcn cv.
T\v i c a l tra n s m ission control protocol/i n ternet proto
col ( TCP/IP ) n c t\\·ork l atencies a rc t\\·enn· thousJnd
ti mes (or more ) l o n ge r th:t n the time i t t'l'picalh' t:1 kes

o r lw cxclu n g i n g messages. Three c a se studies f( > l l m\ ·

a h igh- pedclJ'Iumce S\'Ste m to perform a floating

of progra m m i n g .

rions arc negl i g i b l e com pared with t h e t i m e t;1ken to

A One-dimensional Finite-difference A lgorithm

C o n side r a s i m p l e o n e - d imensional grid pro b l e m 

klism wou l d be a n c r loss, si nce t h e total execution

the m o s t m i n d - bogglingJ y s i m p l e i l l ustr:J tion o f J-! P l-'

latencv.

ll'h i � h i l l ustrJte the d ata pa rJ I Ic l and the S l' tVI D srvks

i n actio n - i n w h i c h e a c h g rid val ue is u pd ;Hcd as

poi n t opera tio n . T h u s C\'en 7 5 0 floating- point oper;l 
comm u n i cate . I n the a bove e x a m p l e , nct\vork par T h e s i m p lest \\'J\' t o i m �1ginc p

FORALL

( ! =2 : N X - 1 , J = 2 : N Y - 1 : Z , K = Z : N Z - 1 : 2 )

U ( ! , J , K )

=

FACTOR* ( HSQ* F ( I , J , K )

U ( I -1 , J ,K )

+

processors. T h e beaut\' of H PF is t h :l t a l l of t h i s c a n be
done i n the con te x t of m a t h e m atics rather than i n the

U ( l+1 , J , K )

+
+

code ti·a g m e n t i n f i g u re I i l l u str;l tes how t h i s is done.

&
&

On nvo processors, the two col u m ns of the

�

assi g nme n t causes one o f those co l u m n s to be move i

The d istri b u tion d i re ct ive lays o u t the a r r ;1 y so that

to the othe r processor. This kind oL1n o pe ra tio n begins

the ti rst d i m e nsion is completely contained w i t h i n

to p rovide progr;1 m m ers with e xp l ic i t wavs to con trol

a processor, w i t h t h e o t h e r two d i m e nsions block

d a ta co m m u nicJtion ;md thc rdi:>re to more e x p l i ci tl v

d i stribu ted across processors i n recra n g u l : u· ch u n ks .

m a n age the associJtion o f d ata and operations to

T h e red-b l a c k c h e c k e rboa rd i n g i s pedi:mn e d a lo n g
the second and t h i rd d i me n s i o n s .
FortLln

processors. Notice that the progra m m e r need not be

N ote :�lso t h e

expl i c i t about t h e pJra l l c l is m . I n fact, scien tists ,m d

90 ri-cc - to rm synt:�x e m p l oved h e r e , i n w h i c h

engineers rJrclv ''';m t to e x press pJra l l c lis m . In tvpie1l

the a m pe rsand i s u s e d as a n e nd - of- l i n e conti n uation

messagc- pJssi n g progr;1 ms, the messages often express

state m e n t .

com m u n icJtion oh·ector and atTa\' i n t()rn1 ation.

I n t h i s e x ;lmpk, the para l l e l i s m is s i m i l a r t o t h a t
of the o n e - d i rn e n siotl J I

ti n i t e - d i fkrence

However, despite the rc n·e n r hopes of progra m mers,

e x :t m p l e .

t h e re a rc ti mes when a p::1ra l l d a l gorith m c1n be

However, communication now occurs along t h e two

d i mc n sion J I bou nd a ries between blocks. The H PF

expressed most s i m pl y :1s :1 col l ection o f i n divi d u ;l l

i n s tr u cti o n streams opcoting o n local datJ. T h i s SPM I )

commu nications.

comp i l e r is respons i b l e tor t h ese

U 

U( : ,Z)

1

MOVE

A

VECTOR

BETWEEN

PROCESSORS

Fig u re 1
Code Ex,l lll p k Showin g Con tro l of Data Co1nnJ u u i carion \\·i rhout Ex p ression of Para l l e lism

Digital Techn ic-;tl )ourn.tl

Vol . 8 No. 3

I <)')(>

43

CALL

C F D(V)



comp l ex

C F D ( VLO C A L )

: :

VLOCAL

: :

VLOCAL

work

w i t h

v l ocal>

END

Figure 2
Cmk E x ;l m p l c of l\Jra l k l A l g o rith m Ex f>rc·w,;d a s Col lection o f T nstruction S trc;uns
as "Amlb h l 's LJ\\·" ) . I n the cJsc

D t u·i n g these l�1st tC\\' vears of the second m i l l e n n i u m ,

rems, the \\T:Jk l i n k \\'o u l d be the i nrcr-SM P com m u 

sist of c l usters of sh arcd - m cmorv S M I' c o m p uter s .

nication ;lnd

T h i s e x c i t i n g dc\·e l opmcnr is the logiul res u l t o r· t h e

o f l o u l comn1 u n ie;1rions op r i l ! l i zarion s . E x pe r i m e n t a

opon c n ti;l l i ncrease in p c r rcm n:mce o f m i d - priced

tion \\·i l l be ne CCSSr e i ght p rocessors ( m ore

t h i n g is certa i n : The fu tmc w i l l

nor be bori n g .

Summary
fortran \\':JS dC\-c lopcd :md h ;l S c o n t i n ued to c\·okc :-� s

a co m p u ter l ;1 n g u :1ge t h a t i s p J rt i c u l arh· s u ited to

ge nera l ! \ ·, r(>r e ight peers ) . I f t h e progrr i n stance, block - d i s tri b u ti o n d i rccti\'CS, t h e :1th.:cted

extensions t o fortr:l l l a rc

:l lT,l\ 'S \\'Ou ld be sp l i t up i n to eight chu n ks ofc omigu

ous aJTJ\' sections.

The second \\ '�lY o f wr i ti n g p:1r:1 l l c l fortran pro

grams ti.)l' c l u stered S M P svste ms is to usc H P F to

m ac h i n cs. for cxa mple , 011c m i ght writc

are able

s h a red - m e m or y o r c n 

s i o n s ) t o ac hicve para lle l i s m loc:Jlly on c:1ch o f thc SM P
! H Pf $

DISTR IBUTE

(* ,BLOCK )

: :

SUBROUT INE

l f the target S\'Stem consisted of t\\'0 S J\.l l' s�·s re m s ,

compiled t-i.)l' t\\'O peers, then the V :-tiT�l\' \H H d d be d is 

C:lCh \\'ith rcmr processors, and t h e :l b O\'C J1n>gr:lm \\':JS

per SJ'vl P svste m . Then the ro u r i n c , C � D , wo u ld bc
tri b u ted i mo rwo c h u n ks o f co l u m n s - 0 1 1 c c h u n k

exec u ted once per SMP syste m ; and r h c l'Cr d i rectives

wou l d , on e:-�ch system, c a u se pr 
nunce c h a i n ( a n obsen·at i o n t h r c l us ter

ll011 Li n i t-i. m n - !11e l11or\' - ;Kccss

R E G I ON

e x p eri e n ce has s h 0 \\ '11

( PC � ) for e x p l i c i t

Fortr
C*KAP*PARALLEL

e x te n s i o n s

t e r prog1·a m n 1 i n g . TmLl \', the most e x c i t i n g fro n ti e r


E X T R I N S I C ( H P f_LOC A L )

,1rc

s h a red - me m or\' p:lr:l l l c l i t.;l t i o n : 1 n d also data -p:1r:1 ll c l

m u c h of the red i u m th:J t o t h er w ise  m J c h i nes a nd t h e n

to usc

44

of clusrercd SM t> s\ s

Clusters of SMP Systems

;\1 . , '' C :o m 1>i l i u g H i gh

tor Disrrib u t c d - mcmorl· S\·srem,,"
cr

Pcrform;Hl cc �onran
Digito/ Tecb uicol

,·ol . 7, no. ,) ( 1 9 9S ) :=i-2 3 .

4. R . Ktt h n , B .

t(Jr D E C �ortL\11 ;\ 1\d

Lcls u t·c , ;J nd

S . S h �1 h , "The KA P 1\J r�l l l c l i z n

D I-: C : C Pmg 1·,J ms," lJI:l!, ilol

Tech n icol (o u mol. m i . 6 , no. 3 ( 1 9 94 ) : :=i 7-70 .

;:1 .

I-'m c .\;l l n p l c s e c !'mceediu,r.;s rJ Supenomp u t inp, 'l)j
( I f. L E , \l o1 - c m bcr J 993 ) : 8 7 8 -8 8 3 , :md W. G ropp,
E . l .usk, � 1 1 d A . Skjcllum, C'>ing I WI ( Bosron: M IT
.

Prc.\s, 1 9':>4 ) .

6 . 1� . l k n so n ct ;1 1 . , " Dc s i g: n o f D i gi t J I 's PcHJ I I c l Soft11·arc
E 1 1 1 i ro n m c n r , " nt:r.; itrtl 'f i-chu ical.fo / 1 1 '1 101. \ OJ 7, no. 3

( 1 9% ) :

7.

1-' o r

24-38.

c x c1 1 n p l c

s e c A . (;c i s r c r a l . , P I � I f: !'o m/lei I ir/t {{{/

. \ fochiue. ;I I \e1\· Gu ide oud Tu tol'ial j(;r Se!tt w l.:
fJrtmlll'l Contj){{/ inJ,; ( Bostr p c1 r c1 J J c J SOrtW;l i'C c\ci11011StratiOilS and pcr
t(mnancc c h cll·c\Ctni �:.uion o f D igital's h igh-pc r·t(xmancc
s1·sn: r m . He has p u b l i s h e d n u n�er·ous papc1·s on paral l e l
c o l l 1 J) U t i n g m c t h ocb, .1s 11 c l l c1s on to pi c s i n the ti c l d of
j)ll\'sics. B i l l rcce i 1 nl .1 bach elor of science d e gree i n m a t h e 
matics a n d j) l l \ ' s i c s f m m t h e U n i 1-c rs i r v o f B r i t i s h Co l u m b i c1
cllld <1 P h . D . in p h Ysics ti·om J-1 an·c1rd U n i , ·ersm·.

Dig.it.ll Tcc l m i o l )ourn;ll

Vol. 8 �o.

·'

1 9W>

I

Judith A. Piantedosi
Archana S. Sathaye
D. John Shakshober

Performance
M easurement of
TruCi uster Systems under
the TPC-C Benchmark
Digital E q u i pment Corporation and Oracle

C u r re n t i n d u strv tre nds ILl\'C mm'Cd from centra l i ze d

Corporation have annou nced a new TPC-C

computing ofkred

lw u n ip roc esso rs a n d svmmetric

m u lti processing ( S M P ) S\' Stem s to m u l tin o d e , h i g h h·

performance record in the competitive mar-

a\·a i l a b le a n d sel l a b l e s\·stems, c a l led cl u s t er s . T h e

ket for database applications and UNIX servers on the A l phaServer 8400 5/350 fou r-node
TruCiuster system . A performance evaluation

Tr u C i u ster m u l ti c o m p u t e r svstem tor the D i gital
U N 1 X e n \ ' i ron m e n t i s t h e l a t e s t clu ster p r o d u c t from

D igital Eq u i p m e n t Co rpo r a tion . 1 In t h is pa per, \\'e

d isc u ss our test a n d resu l ts on a tou r- n o d e Al phaServcr
8400 5/3 5 0 TruCiuster configuration s u pp o rt i n g the

strategy enabled Digital to achieve record
setting performance for this TruCiuster con
figuration supporting the Oracle Parallel Server
database appl ication under the TPC-C workload.
The system performance in this environment is
a result of tuning the system u n d e r test and tak
i n g advantage of TruCiuster features such as the
M E MORY CHAN N EL intercon nect and Digital's
d i stributed lock manager and d istributed raw
d isk service.

Oracle Para l le l Server data base appl ication. We e va l u 
ate t h i s system u n d e r t h e Tra nsaction P r oc e ss i n g

Pert(m11 a n ce Counc i l 's T PC- C be n c h m a rk to prm·id e

p c r t(J rma n ce res u l ts in t h e c o m pe t i t i\ e market f(>r
d a ta ba se Jpp lications.
The TPC:-C

b e n c h m �1 rk i s a med i u m - c o m p l c x i t\',

on - l i n e trans:tction Jl ro cess i n g ( O LT P ) ,,·orklo:� d . ' ' I t

i s based o n :111 o rd er-enrrv workload, \\'ith d i ff-ere n t
transaction t y pes ra n gi n g hum si m ple transactions to
med i u m -complcx itv

t ra nsac t ions t h a t have 2 to 50

t i m es t h e n u m be r of ca l ls of a s i m pl e transaction! To
r u n t he TPC-C b e nc h m ark on

a

c l ustered system, the

o pe rati n g system and the d ata base e ngine m ust prese n t
a single

chtabJse to the b e n chma rk c l i e n t . T h u s t h e
sys te m r u n n i n g the Oracle PJra l lc l Server

T r u C l u s tc : r

d i fte rs grea th· �i·om a network-based c l uster S\'Stem l)\'

two signiliGlnt katures . f i rs t ,

rhe Di gi t:t l U N I X d istri b
the d istrib u ted

uted ra1,. d i s k ( D R D ) sen·ice e n �1 b l e s

O ra cl e Para l l e l Se n n to access a l l Ll\1' d i s k \'O i u mcs
re gard less of t h e i r p lwsicll l ocation in the c l uster.

Secon d , the Oracle Par,1 l l e l Sen er uses D ig i t aJ ' s d istri b
uted lock maiLlger

( D LM )

to S\'ll c h ronize a l l access to

s h a re d resources ( s u c h as i tJ m e m ory cache blocks o r

disk blocks) ac ros s a T r u Cl u ste r sysrem .

the system u n d e r tes t , \\'e used t h e D RD
sn v ice s to balance t h e d a ta base across
the T r u C i u st e r m u l t ic o m p u t er syste m . The c on fi g 
uration i n c l u d e s a s p ec i i l o ws . In the

The rest of the paper

next sec t i o n , we p rovi de a svnopsis of the T r u C i ustcr

map

tra n s fe rs

ti·o m

t he

M E M O RY

m c m o r v :1cccss i nstructions. Th e u se of

m e m or y store i nstructions ra ther t h a n spe c i a l 1 /0
i nstructions p rc)l 'i d e s low I J tc ncv ( tii'O m i crosecon d s )
-

t e c h nol o gy and i ntroduce the O ra c l e Para l l e l Scn·er,

a n d Jow OIT rhcad f()r a tra nsfl:r o f a m · J e n gth .

Tr u C i u s tcr tcc h nolog1·

with the Oracle relational

up to ei g h t ( t(w r r(>r co n 1 m c rc i a l D LM / D RD - based

d atabase management S\'Stc m . F o l l owi ng th;lt, we gin:

app l ications ) c l u ster me m be rs c o n n ecte d to a c o m 

b c n c h m ;Jrk . Next, 11-e
d esc r i be the system u n d e r test and o u r ped(mnance

supp o rted wi t h i n a c l u s te r arc Al p h aSe r ve r systems of

ev;ll u a t i on m e thodology. T he n we d i sc u ss o m pc r f<>r

varyi ng processor s peed Jnd n u m b e r of processors.

a n opti on a l Ora c l e prod u ct tlut enables t h e u ser to use

an m- c n·i c ll ' of t h e T P C - C

mance meas u re m e n t res u l ts and

co mp a re t h e m with

T b e Tr u C i ustcr r(>r D igi t;l l U N I X prod u c t su pports

m o n cl uster imcrcon ncn. The compute r

The m e m be r systems r u n :1pplicarions ( tor

svstems

exam p le,

com peti ti ve vendor results. Fi n a l l y, 1vc present our

user appl i cations ) , as we l l JS m o n i t o r the sta t e of e a c h

conc l u d i ng remJ rks and d isc u ss our tl l tlll'C work .

m em be r syste m ,

e a c h s h o red d is k , t h e M E M O RY

C HAi'l N E L i nterconnect, a n d the netlvo rk. These

TruCiuster Clustering Technology

c l u ste r m e m bers com m u n i cate o1·er the M E l'd O RY

D i gi ta l ' s Tr u C i us t e r c o n fi gu rati on consists of inter

c o n ti gu ra t i o n consists of a M ENI O RY C H A N N E L

C H AN N EL i n tercon nect.'' � A M E M O RY C H A N N E L
con n ec te d c o m pu ters ( u n i pr o c e ssors or S M Ps) and
e x te rn a l d isks con nected to o n e or mor e s h a red , s m a l l

co m p u t e r systems i n te r C1 ce ( S CS I ) b u ses provid i ng

ad ap t er i nsta l l e d i n J l'C I slot a n d l i n k c a b l es t o c on 
nect the ad a pte rs . I n J co n n gu ra ti o n \\'ith m or e t h a n

two m e m be rs , the M EJVI O RY C H A N N E L ada pters

s c n· i ccs to c l i e n ts . '' It presents a s i n gl e rJII' vo l u m e

are co n n ect ed to a 1YI EMO RY C H AI': N E L bu b . A

i ty t h a n a si n gle system and be tt e r sca l a b i l i ty t h a n a n

CHAN N E L h u b is shown in figure l .

n a i1K spac c t o a c l i e n t with better a ppl i cation a v ;l i la b i l 

ty pi c al Tru C i ustcr c on fi gu ra t i o n with a M E M O RY

SM ! ' . A Tr u C i u ster c o n fi gu ra t ion s u p ports h i gh l y par
a l l c l izcd d a ta base m a nagers, such as t h e Oracle PJ ra lkl

A p pl ica t i on s ca n atta i n h i gh ava i l a bility by con n ect 
i ng two or

m o re member svstcms to one or more

,- - - SERVER

1

SERVER 2

M EMORY
CHANNEL
ADAPTER

MEMORY
CHAN NEL
ADAPTER
SHARED STORAGE

LOCAL STORAGE

F i g u re 1
A Tr u c : l ustc r Contigmation ll' i th M E M O RY C H AN N E L H u b
DigitJ! Tcc h n ic;t\ ]ollm;t\

Vol . 8 No. 3

1 9%

47

s h a re d S C S I b u ses , t h u s con str u cti n g an A 1 a i l a b l e
S e rver Em·i ronmcnt ( A S E ) . A s h a re d SCSI b u s i s
re q u i re d onJv
not

fix two- m e m ber con tigura tions th �l t d o
have a M E M O RY C H A N N E L h u b . A l th o u gh

M EMORY CHAN N EL is t he o n lv s u ppo r t ed c l u ste r
i n tc n: o n ncc r,

Ethernet :md

i m c r raec ( FD D I

fi ber d i s t ri b u ted

c l uster mem hns . The c l u ster comnH1 1 1 i cuion sen i c e is
used to a l l oc :1 te the lVI E M O RY C H .\ N N L I . a d d ress

space �l lld Jll: pmting o f c l us 

:1 ppl ications to r u n ll' i t h i n t h e c l us te r, r ega r d l es s o f

ll 'herc in the c l uster the �J C t u :� l physic:�! s to ra ge resides.
Therdorc a D RD s e rv i c e a l loll's the Oracle Par�1 l l c l
S e r v e r pa ra l le l access to stoLJgc media ti·om m u l t i pl e

T h e fi1'C tl' pcs of
( of 1 0 or d e r l i n e s )

TPC-C

transactions arc l i ste d i n

h·om a ware h o u se r h m u g h

the c o rrespon d i n g stock level f( Jr c�1 e h i t c ll l . N i n e ty 
of rhc rime the s u pp l v i n g warehouse is

n i n e pe rc e nt

WAREHOUSE W

WAREHOU S E 1

1K

. . . . 3K

· · · D I STR ICT 1 0

3K

1K

·

3K

1K

Source: Transaction Processing Periormance Council, TPC Benchmark C Standard Specification,
Revision 3.0. February 1 995 .

Fig u re 2
H i erarch ical Relationship
l)i�iLli Tcdm ical f o u n d

111 the TPC - C : B usi ness t-: m·ironment
Vol . X �o. 3

1 '>')6

I

CUSTO M E R

CUSTOMER

CU STOM E R
1K

·

I

I

I

CUSTOM E R

DISTRICT 1 -

· · D I STRICT 1 0

D I ST R ICT 1

�1 s i n g l e

th tab:Jsc tra nsacti on ; it i nse rts t h e order ,m d u p d a t e s

COMPANY

4X

h i e ra rclw

The

em·i ro n m c m is s h o11·n i n

····

3K

WA REHOUSE

DISTRICT

10

W ' 1 0,95,0.00095'W

W,89,0 000089'W

�

1 00K

STOCK
W ' 1 00K.306.30 6'W

jw

H ISTORY
W,89.0 000089'W

-

3+
N EW-ORDER
W'9K.8.0 0 1 6'W+

ITEM
1 00K,82.8 2

1-l_

ORDER-LINE
W'300K+.54 , 1 6.2'W+

3K

CUSTOMER
W'30K.655. 1 9 65'W

�

�
5 - 1 5 ,--

-

�

1+

ORDERS
W'30K+,24 .072'W+

-----

KEY.
TABLE NAME
CARDINALITY.
APPROXIMATE ROW.
TABLE SIZE
LENGTH (BYTES)
Note:

+

CARDINALITY OF RELATIONSHIP

implies variations over measurement interval as rows are deleted or added.

F i g u re 3
T P C : - C : D �m b�1sc T�1 b l cs Re lationship

Ta ble 1
TPC-C Re q u i re m ents for Percentage i n M i x, K ey i n g Time, Response Time, a n d T h i n k T i m e '

M in i m u m
Percentage
in Mix

Minimum
Keyi ng
Time
(Seconds)

N ew order

N/A"

18

Payment
O r d e r status
D e l i v e ry
Stock l evel

43
4

Transaction
Type

Notes
·'

Table

1

4
4

3
2
2
2

90th
Percentile
Response
Time
Constrai n t
(Seconds)

Minimum
Mean T h i n k
Time
D i stribution
(Seco nds)

5
5
5

12

5
5

5
5

12
10

is p u b l i shed i n the Tra nsact i o n Processing Performance Council's TPC Benchmark C Standard Specification, Revision 3.0, February 1 995.

' Not applicable (N/A) because the measured rate is the reported through put, though it is desira ble to set it as h i g h as poss i b l e (4 5 % ) .

t h e local w a rehouse, a n d on l y one perc e n t o f rhc rime

a c t i o n pro cesses ord e rs correspon d i ng t o 1 0 p e n d i n g

p a y m e nt for a customer, u pdates t h e cus

corresponding e n tr y i n t h e new-order t a b le i s a lso

is it a re m ote warehouse. The payment transaction
processes
to m e r's

a

b :t l a nce , a n d rdl e c ts the pav m c n t i n t h e d i s 

trier a n d

''':tr e h o us e

sales statistics. T h e c u stomn

resi d e nt II ' J re h ou s e is the l oca l ll'a rc h o u se 85 pe rce n t

orders, l tcx each

d istrict with l 0 i te ms per ord e r. T h e

deleted . The d c l iv e rv transJction is i n tended to be e x e 
a queu i n g meclu
nism, rather thJn bei n g e x e c u ted i n teractive l v ; t he re is

c u te d i n d e te r red m o d e t h ro u g h

of the ti m e :t n d is the remote wa re house 1 5 percent of

no terminal response i n d i c a ti n g the trJnsaction com

t h e t i m e . T h e order-status tra nsaction re t u rn s the st:J.

pletion . T h e srod:. - ICI'el

tus of a c u stomer order. The customer ord e r i s s e l e cte d

q u a n t i tl · of stock

60 perc e n t o f t he time b1· last n a m e md 40 percent of

last 20 orders i n a d i s tr i c t :m d d eter m i n es t h e i te m s

t h e ti m e by idcnti tlcati o n n u m ber. T h e d e l ivery tra n s -

that h a v e a stock i c l · c l belo11 a s peci fi ed threshold .

tr:t n s action ex�'lmi ncs t h e
r(x t h e i te m s ordered b � · e a c h o f t h e

Digiral Tcc iJnical ) < >urnal

Vol . 8 No . .i

1 996

49

The TPC- C : pe rt(mlJ:tnce metric measures t h e tot<1 1
n u m b e r of new orders com p l eted p e r m i n u te , 11·i rh •1

\\'Ol'kl oad . T h en we d iscuss t h e tes t i n g st rategv used to
e n h :tnce t h e per rc>n11:1 nce oft he S L'T

9 0 t h perce mi l e response - t i m e constra i m o f S sec o n d s .

We show the confi guration o f t h e c l ie n t-server SUT

T h i s me tric me:tsu t-cs the b us i n ess t h ro u g h p u t cn h e r

i n h g u re 5 . The server SUT consists o f a TruCl uster

t h a n the transaction e x e c u t i o n rate . ' I t i s e x p ressed i n
tra nsactions- per- m i n u te

C ( tpmC ) . T h e metric i m p l i c 

c o n ti g u rJtion

\\'i t h

fo u r n o d e s ; cK h

node

is

an

A l p h <1Senu i\ 400 5/3 5 0 svste m with e i g h t 3 S O 

i t � \' t a k e s i n to acco u n t <1 1 1 the transaction t\'JXS :ts t h e i r

mega heru (!'v! H z ) C: P U s a n d i\ giga !)l'tes ( G B ) o f

i n d i ,·i d u a l t h rough p u ts are con trolled b\' t h e m i x p e r 

m e m mY T h ese nodes are con nected toge t h e r b\'

l . The t p m C is a l so d 1·i, c n b\'
the acti,·it\' o f e m u ! J ted users and the ri·e q u e n C\' of

lv! E M O RY C H A I': l\: E L l i nk c a b l e h·om t h e M E I\ 1 0 RY

ccn t:tge gi\ e n i n Ta b l e

c hec kpoi n ti n g . "' The cvcle t(Jr generJting <1 T P C : - C
transaction b y a n e m u l a ted u s e r is s h own i n h g u r e 4 .
T h e transactions a r e generated u n i t( m n l y a n d a t
ra ndom w h i l e m a i nt a i n i n g :t m i n i m u m perce mage i n

a

CHA:\ � E L <1cb pter on t h e node to a single M Elvl ORY
C H AN N E L h u b . The locJ I storage c o n ri g u ration klr
eJch node consists of 6 HSZ4 0 red u n d a n t a r rav of
i nexpe n s i ve d i sks

( RA I D )

contro l le rs , 3 1 RZ28 a n d

1 4 1 RZ29 d is k d ri,·es, conn ected t o t h e n o d e bv SCSI

buses to 6 K7ol'Sr\ d i sk adapte rs . f m t he r, e a c h n o d e i s

T J b l e l gi,·es t h e m i n i 
each transac t i o n t\'fX , t h e

c o n nected t o 1-'DDI lw a DEFPA F D D I :td ap te r. The

m i n i m u m ke,· i n g r i m e , t i J e m a x i m u m 9 0 t h percentile

nodes co m m u n i u te \\ i t l1 the c l i e n ts 0\'C r t h i s F D D I .

m i x for e a c h tranS<1ction t\' p e .
m u m m i x p e rce m:tge t( Jr

response - t i me consn·:� i nr , and the m i n i m u m t h i n k

T h e c l i e m S UT consists of 1 6 A l p h :tSenn 1000

T h e d e l i\·ery transacti o n , u n l i ke the other tr:t n s 

4/2 66 S\'Stems, each ,,·ith 5 1 2 MB o f memo n·, one
RZ28 d i s k d ri,·e , and one D E F PA F D D I adapte r 1 2 The

t i m e d ctin e d lw t h e T P C : - C : specificati o n .

m c l i e n ts associated with eac h node Jt'C

i n te r val a n d the l e ngth of the c heckpoi n t i n g i ntcr

connected to

\'a l . The TPC-C: speciticnion, however, d c tines the

D EC : h u b 900 p md ucts contains t\\'O concentra tors,

a

DECh u b

900 swi tch . Each of the t() u r

u p pe r bou n d on t h e c h ec k p o i n t i n g i n tuv:t l to be

one

30 m i n u tes "

( UT P ) coiKentrn 1 1ance

i nst�J I !e d o n each c l u s ter m e m ber. The software config

e\·a l u ation of t h e Tn1 C i usre r S\'Stem u n d e r t h e T l'C : - C :

urati on i n s LJ i l e d on e :t c h c l i e nt S\'Stem is t h e Digital

S E LECT A
TRANSACTION TYPE
FROM MENU

MEAS U R E MENU
RESPONSE TIME

KEY T I M E : TO
ENTER R EQU I R E D
INPUT FIELD

DISPLAY SCREEN

M EASURE
TRANSACT! ON
R ESPONSE T I M E
THINK TIME: WHILE
SCREEN REMAINS
D I S P LAY E D

Fig u re 4
c,·c l c ri:>r Ccnerating
50

a

Digi u l Tcch n i c1 l J o u rn,11

TPC-C Tra nsaction l)\' an Enl l l L1 teci User

1 ---

DISPLAY DATA

6 HSZ40
RAID
CONTROLLERS

6 HSZ40
RAID
CONTROLLERS
M EMORY
CHANNEL H U B

3 1 RZ28
AND 1 4 1 RZ29
DISK DRIVES

8-CPU. 8-GB
ALPHAS ERVER 8400
5/350 SYSTEM

6 HSZ40
RAID
CONTROLLERS

FDDI

3 1 RZ28
AND 1 4 1 RZ29
DISK DRI VES

8-CPU, 8-GB
ALPHASERVER 8400
5/350 SYSTEM

6 HSZ40
RAID
CONTROLLERS

FDDI

3 1 RZ28
AND 1 4 1 RZ29
D I S K D R IVES

3 1 RZ28
AND 1 4 1 RZ29
DISK D R I VES

4 VAXSTATION 3 1 00
WORKSTATIONS

4 VAXSTATION 3 1 00
WO RKSTATIONS

4 VAXSTATION 3 1 00
WORKSTATIONS

4

VAXSTATION 3 1 00
WORKSTATIONS

16 ALPHASERVER 1 000 4/266
SYSTEMS

Figure 5
Cl ie n t-Server System u n der Test

U N I X ve rsi o n 3 . 2 D o pera t i n g system and rbe

BEA

Tu x e d o Systcm/T ve rsi o n 4 . 2 rr.ms:K tion p r o cessi ng

m on i tor. t:u r t h c r , each RT E ru ns the O p cnV MS oper
a t i n g svstcm and a p r op ri c ta rv e m u l a tion p:1e bgc,
VA X I\T E . In the re m a i n d e r of this se cti o n ,

11·c

d i sc uss

the r e s t i n g srrareg1· used to gc n c r :nc the rr:msac tions
on the h·onr end . Then \\'e d isc u ss the t u n in g done on

descri bed i n Ta b l e

I ) with a u n i q u e seed . This ensures

the mix is we l l d c ti ncd a nd a 1·aricrv o f transaction
t ypes arc r u n n i n g cotK l l tTcntlv ( to better s i m u L n c

a

real -ll'orld uwiro n m c n t ) . We had a local aro tr:: tn s 
porr ( LAT ) conn e c ti o n onT

e m u l ated user and

E th e rne t

betll'ec n each

a c or res po n d i n g TPC c l ie nt t( >rm

process on rhe c l i e n t t(lr ta s te r com m u nicati o n . \Ve

the bac k. e n d ro achin·e the m :n:i m u m possi ble tp m C

s h o ll' the com m u n icnion b<:t11·een an RT E, a c l ie n t ,

mc1s urc mcnrs ti·01n t h e SUT.

a n d a scn·cr i n figure 7 .

u s e d a series of RT E s ro d ri 1· c the S U T . The o n e - to 

sp o nd ing to a tra nsaction rvpe, w h i c h a l lowed us

ln con r(mnance \\'it h the TPC-C spcci ti cni o n , \\'C

on e corres p o n d e n ce between c m u Ln c d users on t h e

vVc b u i l t ti 1'C ord e r q u e ues on each c l i e n t cor r e 

ro

con trol the tr: msaction pe rce n tage m i x . A T P C c l i e nt

1\T F. :m d the TPC c l i e n t fo rms o n the c l i e n t req u i red

to rm process q u e u es tr:lllsactions gen e ra ted bv r h c

us ro d e ter m i n e the max i m u m n u m ber of u se rs ro be

e m u l a te d users t o the :1 p p ropriate o r d e r q u e u e u s i n g

ge n era t ed

lw the RTE .

T h e m a i n bctor we used ro

d e tcnn i n c the n u m be r of users \\'as the cl i e nt ' s m e m 
orv s i z e . We assumed t h a t o n a c l i e m, 3 2 M B o f m e m 

Tuxedo l i brarv

calls. These transaction requ ests i n

e a c h q u e u e a rc processe d i n a tirst i n , fi rst o u t ( r l r O )
order b v t h e Tuxedo sen·cr processes r u n n i n g o n the

tor

client. We h a d 44 Tu x e d o scn·e r p roce ss es th:n 11·crc

constra i nts, c1ch RT E generates 1 ,6 2 0 e m u l ated users .

\\'ere d istri b u ted s o r h a r r h e n u m be r of Tuxed o sen·cr

T h e e m u btcd u sers then generate tra n sactio n s ran 

processes d e d i c a te d to a q u e u e w a s d i recrh' corre L 1 rcd

or l '

is u s e d tor t h e opera t i n g s1·ste m a n d 0 . 2 5 t\!! B

eJch TPC : c l i c llt to r m process . The rdi:ltT, \\ ' i t h these

domlv b:1scd on t h e p re d c ti n e d tra nsaction m i x ( a s

nor e1·e n h · d istri b u te d :1 mong t h e

5 order q u e u es b u t

to the pc r ce n t:1gc of the m lrkl o a d h a nd led lw t h e

Digitl'e the dat:� b ase hit rati o . 13eGl llSC <\I I vendors sub
mitting T P C - C re su lts u s e t h i s stvlc of tuning, the per
t( mnance l i m i tat i o n tor TPC:-C is usu:� l l v t h t: back-end
server's CPU powe r. In fac t , rests have s hown that i f
this method of t u n ing i s n o t tol lowcd o n rhc back-end
server, rhe user will no t obtain the opr i m J I TPC-C pe r
t(mnance res u l ts . I ns tea d , the tests reveal J back-end
s c n n c on figu rati o n that has 1 10t fu l l v util i zed the
scrH:r's pote nrial Lw h aYi ng u n baLmced C P U Jnd ljO
ca p ab i l i tie s . T h is tvpc o f con ti gu rJ t i on nor onlv red uces
the se n·cr's through put c a pa c i t\' b u r :1 lso adl nsc h
aftccts the price/performance of the S U T.
On t h e back end , 1\'e used Tru C l uster t cch nologv
te�ltures to a c h ieve t he max i m u m possi ble tr:�nsr t h i s conti.guration, a system of this
size s u ppo r t i ng the Oracle Para l l el Se r v e r req u i res
1 million locks ( o c c u p y i ng l C B of m e m o r y ) t()r the
DLM when u s i ng S . O GB o f m e morv to r the SGA.
Agai n b e u ristiCJ l lv, we o bsen·cd t h :.J t if we used less
m e m o rv for the D L!Vl, rhc rot:� I n u m b e r of locks per
page ll'aS red u ced . The decrease in locks per pJg.c
i n c reases conte n tion �K ross nodes a n d hence red u ces
the tpm a s rhe n u m ber oh10des increases.
With t h e h e l p of e n gi neers ti·o m D i gi tJ l ' s
M E M O RY C H A N N EL Group, 11 e \\Tre able to usc J
h a rdware data :� n a ly z cr to m e �1 s ur e t he pe rc e n t a ge of
the M EM O R Y C : H t\ N N EL i merconnect's band11 i d th
used when r u n n i n g the T I�C-C: be nch m :1rk. By usi n g
the d J t a ana lyzer, we determined t h at we do not
a p p ro a c h saru ration of t h e PCI - based M E M O RY
C HAt"JNEL h a rdware d u r i n g a TPC-C rest, even
though i t is c a p:1 bl c o f s u sta i n i ng a peak t h r o u g h p u t
rare of 1 0 0 J'vi B / s . In bet, ll't o bsen · e d that rhe
M E M O RY C H A N N E L bandwi d th 11·as nor saturJtcd;
a TPC-C tes t req u i red a pc1 k throughput rare of
o n l y 1 5 M B /s to 1 7 M l3 /s ti-orn th e l'vl E M ORY
C H A N N E L . As stJted previo us h·, the b c n c h m r

J

m i n i m u m of 1 60 m i n 

u tes . '" T h e measur e t n e n t o n t h e S LI T began approxi
mately 3 m i n u tes a fte r the s i m u l a ted users had begu n
e xec u t i n g tr:\llsacti u n s . The m easure ment period of

Beu use t h e M EM O RY CHAi'JNEL i n terconnect not

1 2 0 minu tes, hm1·e1·er, started arter the SUT attained ;1

o n k h ;ls s u fticient ban d"id t ll tc>r T P C : C b u t a lso pro

stead1· state i n a p proxi m a te[\- 3 0

,·ides c x ce.l l c n t l a te n c1· ( less than 5 microseco n d s ) , ll'e

ment 11 ith t h e T l' C - C : specification , we p e dc>rmed

;l tT  3

I ')'J 6

more to e m u rc the rcprod u c i b i l i n· of the m:n:i m u m
mc1surcd rpm C. Dig i t:� ! Equipmellt Corpor a t i o n and
Oracle Corpo cH i on :� !so present a pricc/ped(mnance
ratio o f $ 3 0 S p er rpm C.
I n T:�ble 3, II'C prese n t the rota! occu rrences of each
tra nsaction tq1C �1 11d the percen tage n-�m sacrion m i x
used ro generate t h e tra nsactions i n each rest r u n . vVe
com pa r e tilL' t)erc c n ragc rr:msacrion m i x i n Ta b l e l
.

Acknowledg ments
M �my peopl e \\'i t h i n se\'eral gro u ps �1 11d d iscipl i nes

6.

t h e t(> l l owing ind ivid uals trom D i g i t al : Lee A l l i son ,

B h agyam

M oses,

Ruth

7. W.

CSD Pc rtormance Group; Brian S tc\ ' e n s a n d

j i m Wood \\'a rd , D i g i t a l u�IX Pc r t( m n �l n c c Tc:ll11
m e m ber; Scan Re i l l v, D o u g 'vVi l l i a tns, a n d

Z:1rb

c ;, c t:t n m i c o f t he AVS Pertormancc (; m u p ; �md Don

8.

Vi p i n C o k h a l e of the O rac l e Perr(mmncc G rou p .

References and Notes
I . Throughour th is pa pe r,

ll'e

u s c r h e rcrm c l u s r c r i n tcr

W K o h l e r , A. S ha h , ;1 nd f . Ra�1 b , "On: r , ic\1 o f TPC
lk n c h l n ;uk C: The O rd n E n tn lk n c h 1 n ark" ( Trclns

;lc t i o n

Pmu:ssi ng: Performance

C :o u n c i I, Tec h n i cal

1\cpon, l) cce m b n 1 99 1 )
3.

TrJ nsacrion Proc.:ssing Pe d( m n a n cc Cou n c i l ,

ll'C

/!euc/JIIIrtd' (.' Sian do rd ,\jJeciji'utl lou. N£ 'n'sion , ) . 0.

h: b rtL1 r\ ' 1 9 9 5 .
56

Softll':lr<.:

Ca rd o z cl , F. C l o\'cr, a n d W . S n a m a n J r. , " Design o f

5-1 7.

7i·uCius!er .')ujitmre.

Hordu w·e

COJ!/i'g u ra ! ion

( JVLl \' lu r d , M .1. ss . · D i g, i t .1 l E q u i pme n t C:orporcuicl l l ,

9.

J i'II CI!Is/cr. Sujitt·ru·e lus!alla!iull

and

C(,uf%� u m 

tion ( M a\' ILlrd , M .1ss . : Digital Eq u i p m e n t Corpor:l
t i o n , O rd e r :\' o . AA - (2 1 .8 ,\ IA-TE, September 1 99 5 )
10.

C hec kpoi m i n g is a p mce ss ro m a ke the cop\' of t h e
d a tabase records/pages on t h e d ur a b l e m ed i a c u r r e n t ;
S\'Ste m s do n o r 1\' ri r L· r h c mod i ticd records/fJages of
t h e daL1bc1sc ,H rh e t i m e o f the mod iticarion b u r at

c l l �ln ge a blv ll'ith TruCiuster.
2.

Corporation,

Order N o . AA - Q L 8 l .A - I t-: , Dece m b n 1 99 ;) ) .

H �1rherr and Pa u l ine N is t , t h e te st sponsors. LJstk, \\'e

�1 nd

Eq u i p m c nr

U N I X t-: m· i r o n l l l C I H , " nt:l; i!ol Tech nical jou nwl.

·

\\'O u l d l i ke ro t ha n k Jef Kennedv, Pcrcr LJ i , K�1 rl H �1as,

D i gi t a l

' ol . 8, no . I ( 1 996 ) :

S�mj:1v NarJhari, Dave S ta n l c,·, :111d G reg T�1 rs�1 o f
the

PCJ ,"

( h b r u cH' \' 1 996 ) : 1 2 - 1 9 .

rhe Tr u Ci usrcr 1Vl u l ri c o m p u t e r Syste m fo r t h e Digi r J I

iV!orgc n s te i n ,

T i m B u rke of t h e D i gi ta l l! N I X Eugi nc<.:ring G roup;

I

1 6, no.

Prod u c t Descri ption 6 3 . 9 2 , October 1 99 5 ) .

Ro ger Desc he nes, Tared' K:�w:�f, M :t r i a Lopez, Joe

ivlcl-'add c n ,

1 ol .

TmCIIIsler ji11· 1 Ji,� i!o/ I .\IX I (T-;fon I 0 ( M a l ' l l a r d ,
M as s . :

i n both D i g i u l and Orac l e co n t r i b u ted to t h e s u ccess

o f th i s pertl lows :
l.

Forty-three pe rce n t -A new-order tra nsaction
p l aces an o rd e r ( a n average of 10 Jines) ri·om a war e 
h ouse t h r o u gh a si ngle database transaction and
upd a t es the corr e sp o n d in g stock le\·el tor each item.
I n 99 percent of the ne w - ord er transactions, the
supplyi ng warehouse is the local wa rehouse and o n ly
1 p erc e n t of th e accesses are to a remote w are h o use.

2 . Forty - th re e pe rc e m -A payment transaction
processes a payment t()r a customer, u p d ates the cus
tomer's balance, and reflects the payment in th e
d istrict and wa re h o us e sales statistics. The c ustomer
rcsidem warehouse is t h e home warehouse 85 per
cent of the ti m e and is th e remote warehouse
1 5 pc rce ll t of the ti m e .
3. Four percent -A n order-status transaction returns
the status of a customer order. The customer order is
se le ct e d 60 percent of the ti me by the last name and
40 percent of the time by an identification n u m ber.

4 . Fo u r perce n t -A del ivery tLmsacti o n p ro ce sses
o rd ers c o r res p o nd i n g to 10 pe n d i n g orders tor each
d i st ric t wi th lO i te ms per order. The co rre s p o n d ing
entry i n the n e w- o r der table is a lso d e l et ed . Th e
d e l i very t ransa c ti o n i s i mend ed to b e e x ecu te d i n
deferred mode t h ro u gh a queu i ng mechanism .
There is no term i n a l r esp onse for co m plet ion .
5 . Four pe rcen t -A

s to ck -l e ve l t ra n s ac ti on CXr D ig i ta l's Al ph a
environ ment. As a group chartered to measure database
p e rtorma n ce on Alpha syste ms, D i gi tal ' s Co m p u ter
S ys t e ms D i v isi on ( CS O ) Perfrmancc gai ns .
Figure I shows code seq u e n ces that Digital's C S D
Performance Group has given to d atabase ve ndors to
i m p ro,·e locking i n trinsics i n the Alpha em ironment.
These code seque nces can be used to i m plement spi n 
locks i n the D E C : C compil e r on the Digita l
NIX
operati n g svst e m .
Using O M Feedback

As previously m e n tioned, O M is a post- l i n k rime opti 
m izer available on the Digita l U N I X operating system .
I t pertorms opt i m i za tions such a s compression o f
add ressing i nstructions m d dead c o d e el i m i n a tion
t h rough the usc of fee d back. The pertonnancc
i m p rovem e n t provided Lw OM o n Alp h:t 2 1 1 64
systems is d ramatic f(x rhc tc> l l oll'ing two reason s . '
•

The 2 1 1 64 m i croprocessor has a n 8 - k. i l o lwtc ( KB )
d i rec r · m dppcd i nstruction c a c h e , \l·hich m a kes
code p lacement c xrrc mch' i mporta n t . In a d i rect
mapped cac h e , t h e cod e Lwo u r and l inking order
maps one rr>r o n e to i ts place m e n t i n cac h e . Thus
a poorlv chosen instructi o n stream l a y o u r o r s i m 
p l y u n l u c ky c o d e p l a c e m e nt vvi t h i n l i bra ries c 1 n
a l rer ped(mnancc b y 1 0 t o 2 0 perce n t . Rou ti n e s
a re freq u e n t l y page a l i gned , which c a n incrc:Jsc
the like l i h ood o f c1ehc c o l l isions .

•

The h i gh c l o c k rate of the Al p h a 2 1 1 64 m icro
processor ( 3 00 to 500 megahertz [ iYl H z ] )
req u i res a cac h e h i c rarclw to attempt to ketp the
C P U p i pe l i n es fi l l e d . The p e n a l tY o f a first- l eve l
cache m i ss is 5 to 9 c\-c lcs, ll'hich means t h a t an

Digit�! Tec h n i c a l J o u rn a l

Vol . 8 No. 3

1 996

6l

/ / T E S T _A N D _ S E T i m p l e m e n t s t h e A l p h a v e r s i o n o f a t e s t
/ / t h e Load- Loc ked . . store-cond i t i ona l i ns t r uc t i ons .
/ / func t i on
/ /va lue i s

i s
0,

t h e store-cond i t i ona l f a i l ed, t h e va l ue of the s p i n l o c k
a f a i l u re status (0,2, or 3 )
is retu rned in RO.

II

I
I
I
I
I

I
I
I
I
I

status

retu rned

in

RO

i s

one

of

the

f o l low i n g :

0

-

f a i Lure

( sp i n l o c k

w a s

c l ear;

1
2

-

success
fa i Lure

( sp i n lock
C sp i n lock

was
was

c l ea r ; now
set; s t i L L

set )
set,

-

f a i Lure

( spi n lock

was

set;

set)

3

#def i ne

TEST

set opera t i on us i ng
purpose of th i s

t o c h e c k t h e v a l u e p o i n t e d t o b y s p i n l o c k _a d d r e s s a n d , i f t h e
set it to 1 and ret u rn success ( 1 )
in RD .
If e i ther the spi n lock

/ /va lue i s a l ready 1 or
/ / rema i n s u n c h a nged a n d
/ /The

and
The

AND

SET

s t i l l

s t i L L

( s p i n l o c k _a d d r e s s )

c l ear,

asm(

s to r e-cond i t i ona l

s t ore-cond i t i ona l

fai led)

$0, ( $1 6 ) ;

" Ld l
"or
"st l
"s l l

f a i led)

$0, 1 , $ 1 ;
c

$1 , ( $ 1 6 ) ;
$0, 1 ,$0;
$0,$1 ,$0

"or

\
\
\
\
\

C s p i n l o c k_ a d d r e s s ) ) ;

I
I
I
I
I

I
I
I
I
I

B A S I C _ S P I N L O C K_ A C Q U I R E i m p l e m e n t s t h e s i m p l e c a s e o f a c q u i r i n g a s p i n l o c k . I f
the spi n lo c k i s a l ready owned o r t h e store-cond i t i ona l f a i l s , th i s func t i on
spins unt i l
spi nlock i s

#def i ne

{

the sp i n lock
acqu i red .

i s

acqu i red .

Th i s

funct i on

doesn ' t

return

B A S I C _ S P I N L O C K _A C Q U I R E ( s p i n l o c k _ a d d r e s s )
Long

status

wh i le

{

0;

=

( 1 )
i f

{

C * C s p i n l o c k_a d d r e s s )

{

= =

s ta t us = TEST
i f ( s ta tus ==

0 )

AND
1 )

SET

( s p i n l o c k_ a d d r e s s ) ;

MB;
b r ea k ;

}

unt i l

the

\
\
\
\
\
\
\
\
\
\
\
\
\
\
\

F i g u re 1
C(ldc Seq u e nces tor I ncki n g; l nr ri n sics

i n srruction - c a c h c m iss r:nc o f 1 0 ro
c tfecti ,·cl,· s ta l l the C P U 7 0 to
ri m e .

1 2 p c rce nr can

•

C o n v e rse l 1·, d e c re a s i n g t h e

m i ss rate b1·

•

2 pnc e n t can i n c rease t h m u g h p u t bl· 10 percent.
O lv\ pertorms

pro fi le- based

opti m i za t i o n . A p ro -

r eg i ons con tai n i n g o n h- one en trance :1nd one e x i t ) ,

to

cou n t t h e n u m 

ber of ri mes each block. is exec u ted . The i ns t r u m e n ted
version of t h e program is run
r h ::t r conr a i ns �l
u s e s rlle

p roti l c

ro

cre�lt<:: �l ked back ti l e

of h�1sic b l o c k cou n ts . OM r h e n

ked back t o rcuTa n ge

the b l ocks i n a n opti m a l

\\'<)\' r() r t h e ti rsr - ln · e l cac hes O i l t h e A l p h a c h i p . T h e

d e tai I s of t h e proced ure t(Jr using OM m a1·

be

ro u nd

i n rhe m a n page for cc on the Dig i ta l L! l\: I X opcr:1 t i n g
SI'Stem b u t c a n be s u m m a ri zed as

t(>l]oii'S :

Usc p i x i e to prod u c e prog . p i x i e ( t h e i n s t r u mented

e xecu u b l e ) and prog . Ad d rs ( :t d d n:s�es ) .
•

gr�l l l l is ti rs t partitioned i n to b a s i c b l oc ks ( th a t is,
�1nd i nstr u m e ntat i o n code i s �1d d e d

B u i ld executa b l e ll'i th - n on_s h a rc d ·om options,

prod u c i n g prog.

80 perce n t o f the

Ru n p ro g . p i x i e to pmd u ce 1)ro g . C :o u n rs , ll'hi c h
records the b a s i c b l o c k c o u ms .

•

Noll' b u i l d prog ag:� i n ll' i t h - n o n_sh a red - om - WL,

< > m_i rcorg_reedback.

V LM Results
ht'- u re

2 s h m\·s t h e i n cruse in th ro u g h p u t real i zed

,,· h e n u s i n g V L M . �ore t h a t t h roughput nearll· d o u 

m·cr:t ll S\ 'S t e m

rhe data base

62

I )i,:itJI Tcc h n icJI JournJI

Vol . R No. 3

I 96

M a ny peopl e h·o m

:t \ �wi e t\' o f groups th ro u gh o u t
D i g i ta l h el p e d r u n e :t nd d e hc r t h e T P C - C res u l ts . I n
pa rt i c u l a r, w e w o u l d l i k e to t l 1a n k Lee Al l is o n , Roger
De s c h e nes , J o e M c f a d d e n , B h agya m Moses, a nd
Cher\'1 O ' N e i l l ( C :S D Pcr tiJrm Ur
node AlphaSenn 8400 5 / 3 5 0 c l u s ter svsre m running a
state-of the - art d atabase a pp l i c a t i on . Tarcef has recei1 cJ
rwo exce l le nce a w a rd s rl·om D i g it a l tor his "·ork in T P C - C
p erfo r manc e mcJsurcmcm o n the A l p haServer 8000 series.

Fol ey, W. Gist, S. Va n Do t· e n , and

D . Wissel ! , "The Al p haSc r v er 8000 Series: H i gh -end
Server

Pl:ttrC:mn

.fuu mal. vol .

Deve lopme n t,"

Dif:!Jial Techn ical

7, no. 1 ( 1 99 5 ) : 43-6 S .

2 . At the r i m e r h i s puision 3 . 0,

l'<.:bru;ny 1 99 5 .
5 . W. Koh l e r, A. Shah, and R . Raab, Ouerview

of TPC
l.Jenchmark. The Order Enfly Benchmad<. Te c h n i ca l

Report ( Transaction P ro c e ssin g Performance Counci l ,
l)c.:c c m bc r 1 99 1 ) .

6. MOI'c i n formation a bou t the TPC:-C bench m a rk nuy

1K o b t a i n e d From tl1e TPC: World W i d e Web sire,

I mp : //1\ww. tpc .org.

7. j. S h a kshober r better \\'a\'S to col la borate Oil the I nternet.

t h e I n te rn e t user pop ul ation has gro\\' ll , so has the

Some e x a m p les I n c l u d e tile a b i l i t\' to s h are and d i scuss
issues of c o m m o n i n terest, coa u t h o r d o c u m e n ts, :\ lld
track proj e c t sr.nus. Al t h o u g h tolL w's

W W W is ideal

for p u b l i s h i n g i n r(mn ati o n , i t req u i res considerable
c us to m i zed progra m m i n g to s u pport colla boration .
T h e AltaVista For u m version 2 . 0 prod u c r is both a set
of coiLl borati,·e ap pl ic:n ions and <1 too l k i t ( p latform )
that bci l i tates C:1S\', e fti c i e n t , J n d rapid de1·e l o p m e n t of
U N I X and Windoii'S NT s\·sre m s .

col la bor,Hii'C app l i cations fo r t h e Imemct fo r both
I n t h i s paper, \\'e d escribe o u r e x p e ri e n c es i n b u il d 

ing co l l a borJtion sofu,·arc f() r t h e I nt e rn e t . We begin
with ,1 brief d i scussion of

W W W tec h n o l og\' and

p h i l osophy a n d t h e h·amework of the softw:m: and d is

grou pware applications. Then we pre sent om design
cuss

the appl iutions s u p p l i e d b1· Al taVistJ Foru m .

Fol l o\\' i n g t h :n , \\'e d i scuss the ,·arious C \ pc r i e nces

gai ncd in dn-c l o p i n g sofu\'Jrc to r the nc" I n te rn e t

parad i g m . vVe con c l ud e the paper lw d iscu ssi ng o u r
p l a ns tor fu tu rc de1·e l opmenr eft(>ns.

World Wide Web Tech nology
Tod a\''s Inrcrnct \\'JS origi n a l l y
c o m p u ter

ne t"·or·k

that

a

go,·c rn m e n t - funded

fa c i l i tated

c o l l a boration

among :1c1de m i c researchers. l n r(mllation exc h a n ge
\\'J.S c o n d u cted
and

til e

lw mcms of ele ctro n i c m a i l ( c - ma i l )
o,n t i m e , b u l l e ti n - b oard st\k

tr�1 11Skr.

d i scuss i o n s "·ere s u pported b\' the N c t\\'Ork Ne\\·s

( N NTP ) , ll'b i c h propagJted rc �tual

discussion t h reads ro a large n u m be r of NNTP senns

Tra n s fe r Protocol

for viewi ng. \V i t h the d evelopm e n t of the

W W W tec h 

n o l ogv, c o l b hor�l t i n g over the I n te rn e t h ;�s become
e\'e!l eJ.SJcr.
The

vV WW tec h n olo gy consists o f the h > l l o" i ng

c l e m e n ts :
•

U n i i'Cl'S<11 rcsouree locator ( U RL),

a

com e n t i o n ror

i n t(x mJri o n n ;l l n i n g and l i n k ing
•

Hype rtext markup l a n guage

( HTlvl L ) , a text-based

JangtL 1ge f(lr i n ftlrnUtion renderi n g
66

Di1;iral Te chnical ) o u rn.ll

•

c l i e n t-sen-cr protocol

r o tnn sport i n form a t i o n

associ:tted ,,·ith a U RL
•

vVe b browser, a program th:tt renders H T M L d o c u 
m e n ts , provi des U R.L cac h i n g , a n d s u pports a
d i rector\' fi.lr U R.Ls

•

Todav, severa l c o m p u te r :t ppl ications faci l i tate s u c h

Hvperte x r Tra n s fe r Protocol ( H TT P ) , a s i m p l e

vVc b server,

J

col l a boration .

•

i n fi.>rmJtion fi·om the We b browsers
•

W W W te c h n o l ogy h as transformed t h e way users
i n fi.>rmation

through

co m p u te r

applications

are

M a n a gem e n t of a set of users a n d g ro u p s
S to ra ge of s h a red i n ti.mnation i n

a

d ata b a s e ( some 

rimes with rcplicnion Clpabi l i ty )

Information Access

access

t h ese

support t h e fo l l ow i n g capa b i l i ties:
•

s e r ver that responds to req u ests for

C o l l ectil-ci l',

known a s grou p'''<1 re . Lotus Notes is a popu l a r group
ware appl ication . '1\-pi c a l h-, grou pware appl ications

networks.

Viewi n g i n tcmnarion sto r<.:d i n t h e d a ta bases by
m e a n s of a gra p h i c a l i n te r t:Kc

•

Protec tion of the c o l l a boration e n v i ro n m e n t when

Access to i n ti.m11ation on the I nternet was p r i m aril\'

nec<.:ssary t h rou gh a u t he n tication ;md access con rroJ

W vV W , users :tre �1 ble to :tccess
tornnr. The com b i n a ti on

neous c l i e n t c n,·i ronmcnrs, s u c h as the M i c rosoft

tex t- based ; with the

i n ti.m11:t ti o n i n m u l t i med i a

of fu n c rion a l in· ( i n formation l i n ki n g, gra p h ic l i i nt e r 
f..1cc, �md u c h i n g ) , extensi bil i n• ( for d e a l i n g with n e w
protocols and n e w i n fo rmation t\'pc s ) , case - of us e ,

and low cost a p p e a l e d to a wide range o f u se rs i n
homes, offices, a n d corporations. I n a d d i tion , t h e
M os�� i c - s ty l c of " po i n t - a n d - d i c k " gra p h ical I n te r n e t
browser has become t h e most w i d e l y accepted user
i n tcrbcc fi.>r network computing.
The most popu b r use of the W W W tochy is f(lr p u b 
l i s h i ng i n f(lrmation, a n d t h e proc<.:ss i s compara b l e to

G rou p,,·arc SI'Stcms :trc b u i l t to run in homoge 
W i n d o 11 s
·

em·i ronmcnt. The1· reh· on specific c l i e n t 

s e r v e r tec h n ol ogv, w h i c h is often proprietary, to s u p 
p o r t remote opcrJtion s .

T h e popu l a ri n· and rapid growth of the I n rerner a n d

the

WWW h ave created a n o p e n , u n i1-ersal , and easv - ro

program i n fi·astr u c t u re t h a t can readily serve several
groupware fu nctions. E n g i n e ers ar Digita l 's I n temer
Sofuvare B u s i n <.:ss G ro u p recogn i zed the porenti:1l of
u s i n g rhe W W W as the u nd c rlvi n g i n frastructure f(Jr
grou pware solu tions :m d at the same time saw th�1t the

t h e wa1· a n <.:wspa p e r pu b l i s h <.:s or a tclc,·ision station
.
bro:tdc asts i n ti.m11 a ti o n . The roks of t h e i n fcm11 ation

groupware appl ications ;l \'a i l a b l e todav ha1·e fc,uu res

prm· i d c r a mi the i n formation consumer arc c l c a rh

features to the

n i zes the pertin en t inform ation, conve rts i t to the

a n d the

ddi ncd . The i n tcm1 1 a t i o n p rovi d e r ga t h e rs a n d orga

HTM L scripting fonnat, a n d m a k<.:s i t :w a i la b l e o n a
Web scn'Cr. The i n formation consu m <.:r, a fru o b ta i n 
i n g i n i ti a l access to the vVe b s<.: rv<.:r ( as o n e m i g h t t u n e
i n ;o the correct: television station ) , can then browse
and search ri.> r various types of i n tcmlution av::J i ! a b l e
on r h :1 t server. T h e l i n ki n g c rmation o n \'arious sen·ers to b e casilv p u b l i s hed
a l o n g ll' i t h th<.: ori g i n a l i n formation .

l n comrast, m u l t i p l e i n formation pr01 ·i d c rs '' ork

in col bborJtion ro ge n e rate the c o n t e n t of s h ared
i n f( mn a r i o n . For the p u rposes o f this paper, \\'e ,,·i l l
assu m e t h a t there is only

one n·rx o f uscr- i n f(mlla

t io n c o l l :� borators.

The W W W is usc fi.tl to r m a n y t\'fXS of c o l l a boration .
for o :.u n p l c , a project team may ne<.:d to keep track of
project status a nd i n d i v i d u a l progress; pcopk with
a common i n terest ( e . g . , fi l m e n t h u siasts ) may wa n t to
sh are �1 nd d i scuss their views on t h a t to pic;

�1

custo m e r

s u pport gro u p m a y n eed a S\'Stem t o prov i d e o n - l i n e
a n sll'crs t o rea l -world c u stomer problems; or se,·e r a l
�1

W W W lacks. Our goal \\'as to add grou p11 arc
W W W to fac i l i tate collaborati o n .

We starr<.:d e x p lo ri n g t h e i d e a of u s i n g t h e I nrcrn c t

W W W t(Jr grou pware appl ications i n th<.: sum

mer of 1 994 . 131' the e n d of that 1·car, \\T h a d b u i l t
a prototype r h ::� t

s u p p o r te d

t h e s i m p l i fied d iscussion

( b u l l eti n - bcxmi ) katu rcs o Lm i n te rn a l prod u c t known

as DEC Nor<.:s . 1 T h i s prototype generated consid e ra ble

i n terest a m o n g activ<.: DEC N o tes users who were

seeking a s i m i l a r sol u tion b u i l t a r o u n d an l mc rne t
i n fl·astructurc. B a s e d on t h e i r kcd back, the prorotvpc
\\'as redesign<.:d :� nd became :1 prod u c t . '
B1· S e p te m be r

1 99 5 , \\'e h : t d b u i lt several col bbora 
W W W. I n a \\'Orkshop

ti,·e app l ications to r u n 0 1 -c r the

o rga n i z<.:d by the World W i d e Web Consorti u m a n d
t h e .Massac h u se tts I ns t i tu te o f Tec h nol ogv, \\'e p a r 

ticipated in d i sc u ss i o n s on h o\\' r o e x t e n d the W W W
tec h n o l ogv t o s u pport c o l l ::� bora ti o n . AJ I t h e \\'mk

s h op participall ts prese n ted t h e i r ideas to the

Collaboration and Groupware

:� urhors ma1· ,,·ish t o w o r k o n

that the

d oc u me n t rog<.:th<.:r.

\V\V W

Consortium t(>r review.-'

Design
I n t h i s s<.:cti o n , we s u m marize o u r d esign p h i l osoplw
and d iscuss the fra m ework and a p p l ications dn·cl opcd

for t h<.: A l taVist:<1 foru m prod u c t . For our d esign , \\'C
adopted an object-ori<.:med :t p proa c h , ,,·h ich m e a n t
that we wou ld haYc t o m od u l a ri ze t h e Yarious compo

nents tor re use and m od i fic a tio n

Digital Tcch niccl l ) o 1 1 rn :1l

.

Vol . 8 No. 3

1 996

67

Design Philosophy

t i m e ; and a nc\\'spapcr r o u r c o l l a boration soft\\'are . A fte r years of experi 

:1 n u m be r of d i\'crsc applicnions . Figure 1 shows the

m e n ting

A l ta Vista For u m tool kit :m d �1ppl ication layers.

and

process, t h e

col l a borati ng

to

d evelop

an

open

Internet developers reali zed that the

I n te rn e t had reached

:1

state ofcriticJI mass. In the case

o f n e tworks and con nectivitv, reac h i n g critical m ass i s
:t tre m e n d o u s i m petlls r(1r agt·cc i n g o n a c o m m o n

The tool k i t is

•

h i c r:t rclw relationsh i p bci l i t\ ' a\'a i l a b l e to those

a l so i ncreases . I n ad d i tion , the \'e n· n ature of the

r bu i l t - i n d a tabase support.'

Another objecti,·e WJS to m�1 kc

c o m p l e m e nts

<1 1ld look t h e m up using a search tool .
•

the d a tJbase l i bran· i n the Berkelev U N l X d i s tri b u t i o n
.

fu nction

provi d i n g a h i g h - speed q u e r y fac i l i ty. for less

l a nguage tor dn-e l o p i n g m ost of o u r a r p l ication a n d

i n g to deal 'll ' ith HTM L d i rccrlv and cope \\'itl1 i ts
S U IT

our software

changes over time . Abstract definitions or· user i n ter

wou l d be easy to porr to a l l the rel e va n t operating

race objects a lso tend to si m p l i �1 and c l a ri�' the code

system platforms. This p r i n c i p l e g u i ded our selection
o f compo n e n ts and h e l ped us iso l a te a smal l set o f p lat

and create a more u n it(mn appc1rance on the screen.
•

fo rm -depe n d e n t f'u nctions i n to a spec i a l l i brary for
A s stated earl i e r, we tried to take a n object-or i e n ted
approach "·hene,·er possi b l e . The alh·antages of ou r

modi t\', a n d de l e te various objects.
•

i n to message c a ta logs ri.1r later tr:mslation to d i fter

ple bcc:tme i nvol\'cd with the software dn·e l op m e n t .
fe asi ble .

I n te rn ati o n a l i z a ti o n . An i nrcrn,n iona l i zation tac i l 
i t\' g l lO\\'i n g :

U S E R LISTING,
R E G I STRATION

CALENDAR
APPLICATION

DATABASE. I N D E X I NG/S E A R C H . G U I L I B RA RY.
ACCESS CONTROL, I N T E R NATIONALIZATION S U P PORT,
P LATFO R M - S P E C I F I C F I L E SYSTEM. AND T I M E S U P PORT. . .

Fig ure 1
A l ta Vista Forum Too l k i t a n d Appl icJtion Layers
68

B u i l t- i n d a tabase . The appl i cnion uses a b u i l t- i n
i s �1 ,·en· s i m p l e re l a t i o n a l m od e l with a n object

the need to r soft'll' a re dc,·c l op m c n t for the Internet

open software as b u i l d i n g b l ocks w h e n ever poss i b l e .

com bination of both C and Tel code

cb t<1base r o s t o n: i ts object i nsLm ccs . The data b ase

stand�1rd . As more and more u sers access the I n ternet,

O u r p h i l osophy a l s o incl uded the re use o f e x isting

a

that creates the fol lowing i n terEKc components:

D

•

•

G Llp h i ca l

o bj e c ts s u c h as d e fi n i tions of bu ttons,

Parameters a rc p<1sscd to the d i spatcher fro m seg

roo l bJ.rs, various objects that a rc parr o f a r(x m

ments of the URL. The d i s pat<.:her p<1rses the U RL i nt o

( e . g . , s e l ec t boxes, rad io b u t tons, c h e c k boxes, text

t h e p i e<.:es that p rm·itk the Ol'era l l control o f t h e pro

boxes ) , and icons.

gra m :

D �1t �1 b�1 se e n rries, the defi n i tions o h l w i r J.ttr i b u tes,

name, (

�md d e fa u l t values.
•

Us e r i n te r bce aggre ga te o b j ec ts such as t<.mns,

views, d ia l ogs , and
•

error

m essages .

De b u l t access control p ol ic i es, i n c l u d i ng d c t� u l t
groups, access righ ts , and t h e i r m :.1 p p i n gs , t o c o n 
tro l w h o c a n access i nd i vid u a l t(J r u m s a n d w h a t
actions t h e v c a n rake w i t h i n t h e m .

This a pproa c h t: n c a psu bt es t h e d e ta ils i n lo\\· - l e\'e l

tions to re use the objects.

c:ts\'

argu mellts.
Ea<.:h to r u m is an i nst�Hl l'C of an app li<.:ation o bject.
For example, m a n y d i sc u ssion for u m s are avai l a b l e o n
va rious topics. Each d i sc u ssion

<1pplicati o n Gln be used to man rum h scr1·n

that

( e . g . , n a ti1·e Lm guJg<.: and preferred d ispLw t(mn a ts ) .

specific

I n a d d i t i o n , grO U f)S c a n be created a n d m od i fi ed

r u ms . As d i scussed e r u ms a nd l in ks to
pcd()rm ,·arious tasks, c g . , rcgistcr oneself, look u p
reams o r join a te a m p crt(mn Air:� V i s ta Forum :� d m i n 
isrrati,·e tasks (if an ad m i n isrr:�to r ) , and so on . For this

:111<.i d iscuss r h e lessons 11·e l e a rn ed a l o n g the \\'J\'.

uscr to log i n

,

In this secti o n , \\'e sum marize some of our experie nces
��

As

res u l t o t· o u r d ecision to rclv on the VVe b brmYscr

�1s t h e u n i\'e rsa l use r i n te r b c e , \\·c had to rcsoh'e some

reason , the co m m u n i tY ,·isra is also c 1 l led the s u m m i t .

u n i q u e user i nt e r bce issues . B c c 1 u s c \\'C c h ose to usc

l n m u c h t h e s a m e \\·a,·,

Te l t(Jr dc,·c l o p i n g h i g h e r- b·c l o bjects , \\'C h ad to cope

�� tom ,·ist:� keeps track of a l l
the t(> r u m s and l i n ks tor :1 gro u p o f users, an d a per
so n a l vista p e r forms this fu nction Fix a s i n g l e user.

with using a n i n terpretive b n g u a ge . We designed the

dat;:J b�lse a n d i n d e x i n g a n d scarch i nt c r b ccs based

Both tcam and perso n a l vistas ctn own torums that a rc

on e x te n si b i l i ty a n d port a b i l i ty go:� l s . F i n a l ly, in t h e

nor visi b le to the p u b l i c comnHmity vi s ta .

d e s i g n o �·

�1ccess con t ro l w e h a d t o cardu l l y wei g h
cons o f s i m p l i c i t)' a n d Hcxi b i l i t)1•
,

r b c pros a n d

Discussion M u c h

a

l i ke

b u l l e ti n - board

d i scussion

gro u p o r D i gita l 's D EC Norcs so fT\\' a re, tb is appl i 

Coping with the User Interface Defined in HTML

Gtti o n permits users to s h a re i d eas o n a set o f re l a ted

Ve ry c a r l v i n t h e d esign phase, \\'C decided to m a ke

to pics. Users create top i cs and replies th:n to rm a h ier

A l ta Vista Forum c l i e n t - i n d e p e n d e n t , " i th the e xcep

a rc h i c a l tree ( a lso kno\\'n as t h rc1dcd topics), prO\·id i ng

tion of dtpende nce on tb e vVc b lm)llscr. This decision

J

11·as b�1scd on the bet that t h e \Vcb browser was a l rcadv

" a v klr users to n avigate through ex isting d iscussions.

arc
also provid e d . These i n c l u de c h ro n o l ogically n avi ga t
i n g t h rou g h i tems not read ; l i sti n g u n read i tems o n l y

avai lable on most of the pi:. Hf(mm. VVc e x p e c te d
b rowse r to become �� u bi q u i to u s nct\vork fi·on t
e n d , a l l ow i n g us t o foc u s on b u i l d i n g groupware fi.m c

a n d selectively read i n g them; a n d sc: t rc h i n g tor topics

tions on the server. This mcmt th:H \\'c were bced w i th

a n d rep l ies conta i n i n g ccrt:� i n words that \\'ere e n tered

the

O t h e r methods of read i n g the existing d iscussion

d u r i n g a p a r ti c u l ar time period b\'

a ce rtain a u thor.

ti·c c l y

th e

t�1sk of d esign ing the user i nrcrbcc usi n g l-JTM L''

S i nce H T M L was C\'Oh' i n g, o u r ti rst step was to

ro

d di n c gt·�l p h i c a l objects in more :�bstract constru cts

d i scuss d i ffe rent topics; this is true t(Jr the fol lowi n g

su pporte d by o ur roo l k i t . Each construct encaps u l ates

Users can also create m u l ti p l e d i scussion fo r u m s

t he s p ec i tics i mo a re prese ntation oL1 gra p h i c a l artifact

�1 ppl icuions as \\'el l .

i n HTI'-1! L i n the too l ki t . T h u s :1s H T M L e,·okes, or as

Doc u ment Sharing T h e d o c u m e n t s h a r i n g a p p l i c J 
to

o rga n i Z-e docu m e nt s o f the same
tlJ i d crs. ln ad d i tio n
it keeps tra c k of versions of the d o c u m e nts, attach 
me nts, a n d comments . As w i th t h e d i sc u ss i o n a p p l ic a 
tion, users can bro\\'se through J n d search f(x spec i tlc
d o c u m e nts using a \':triet\' of methods.
t i o n e n �1 b les

users

type i n to h i e rarchica l l y orga n i zed

,

Newspa per Th e nc"·spaper a p p l i c :�tion

l ets

u s e rs

select a speci fie source of i n t(J rm;ttion :� n d t h e n ddi n e
h i rers t o present o n lv those i te m s of pote n t i a l i n terest.
A good e x a m p l e of a n i n hJrma rion sou rce o n t h e
I n te rn e t is o n e of t h e real - r i me news teeds. Usi n g t h e
ncwsp;�pcr a p p l ication, i t i s Jlso poss i b l e t o read a n d
m o n i tor o t h e r i nform:� tion sou rccs, e . g . , c - m J i I s e n t to
a d istri b u ti o n l is t or i nfo rmation ;� ppcari n g on a set of

\V W W s i re s .
Calendar The

f orum

s e L e c t box s . L a n g u a g e
-ma p t o L a n g u a g e \
-Label

"Select

a

language : "

-LabeL break
s . language

a d d _o p t i o n

Eng l i sh

s . language

a d d _o p t i o n

French

2

1

sel ected

I n this e x :Hl1 p l e , a select bm is d di n c d to b eg i n \\'ith
�� L1 b c l a n d some s p a c i n g 1: 11d t h e n to contain t\\'O
options: E nglish a n d Fren c h , with E n g l i s h as t h e

dcb u l t . The val ues l and 2 a rc i n t e r n a l representations
o f t h e se lecte d values. Also, the nn p ro S\\'itch spec
"

-

"

i �ies that t h i s o bject m u st c o r respond to the l a n g uage
�lttri b u rc in the

database, a katurc that 11·as incl uded to

s i m p I in' d a ta base u p d a te .
calendar

:�p p l ication

p e r m i ts

u s e rs

to e n ter a set of sched u l ed C\'C i l ts ( or a to- d o l is t ) a n d

prese n t t h e C\'e nts as

a c a l e n d a r ( sometimes c:� U c d

a d i a rv ) . T h e a p p l ication s u p ports req u ests to a d d
i tems t o the c t l e n d :�r, rhus :� I l o w i n g the c a l e n d a r t o b e

70

are:� needs to be
upd�lted . For exa m p l e , a s e l e c t box object on a form
m av be defined as fol lows:
t h e page d esign c h a n ges, o n l v o n e

Vol . tl N o . 3

1 996

a ! J b c l is spe c i ti c d , no speciti C l 
represent r h :�r l ;1 bc l i n a parti c u l a r
t( m t o r tvpeface . Neither is t h e :�c tu:l l S[XK i n g to r l a b e l
Note that a l t h ou g h

tion is prO\·ided t o

break specitied . These d ecisions :trc mad e i n the for u m

select box part of the toolkit proce d u re , w h ich trans

language, w h i c h supported o u r goal of rapid a nd

lates this object i n to HTML.

iterative deve lopment of collaborative applications

Most of the early Web b rowsers were single-window

tor the w w w.

base d . This l i m i tation was especi a ll y p roblematic for us

vVe e x te nd ed sta n d a rd Tel to p rovide a set of com 

because most of our applications provide some orga n i 

mands and objects that fo rmed t he AI ta Vista Forum

zation t o the i n tixm a tion conte n t . A m u c h more n a t 

too l ki t : d a ta base, HTM L ge n e ration , access control ,

u ra l w a y o f brows i n g tor o u r e nviro n m e n t would

i n ternationaliza ti o n , user protile m a n age ment, a n d

i n clude at least rwo w i n dows: one showi n g the context

p l atform-specitlc support. M a n y of th ese e x tensions

and the other s h owi ng the content of a speci fi c i te m .

s u pported a n object- based e nvi ron m e n t ( i . e . , the

For this reason, w e i n troduced m u ltiple n a \rigational

enviro n m e n t s u p po r ted sta n d a rd Tel objects and o u r

methods. For example, t h e d iscussion appl ication

s i m p l e i n heritance mechanism ) . T h e use of these

•

Allows hierarc hical navigation ( p revious, next, u p )

•

Al l ows navigati o n i n c h ronological ord e r ( ne x t
u nsee n , what's new)

•

•

e x tensions made it easier to develop appl ications than
i t wou ld have been with Tel (or a n y other language ) ,
a l o n e . As a resu l t, t h ese extensions r(x m t h e basis tor
fu ture development tools.

Provides a category view that lists topics accord i n g

From the begi n n i n g , we k new that the c h oice of

to their category

an i n terpretive l a ngu age was goi n g to i nvolve tra d e 

Su pports content- based search or an i n d e x - l i ke

oft$ . I n fact, performance, w h i c h w a s o u r m o s t cri tical

fi.m ction
Newer versions of Web browsers s u pport tl·a mcs,
which h ave m u l t i p l e win dow - b rows i n g capa b i l i ties
( a l though the standards in this area are sti l l a bit
vague ) . We are u pdati n g our applications to take
advantage of these new features.
Usability studies guided our decisions as we we r e
d esign i n g forms and d i a l og boxes . I t i s l i kely that
m a ny pote n ti a l users o f our p ro d u c t are fam i li a r w i t h
vVi n d ows- stvlc u s e r i nte r face objects. Because th e
earlv Web b;·owscrs ( e . g . , M osaic) were U N fX - based ,
littl� attention was given to provi d i n g a h u ma n 
com p u te r i nterface that rese m b l ed the m o re w i d e l y
u s e d W i n d ows

i n rert:1 ce.

However, o u r u sa bi l i ty

studies ind icated t h a t m 

•

S ho u l d access c o ntrol be d c ti n c d fo r e\'erv poss i b le
access/action tvpe>

tvp ica l ly execute o n l y o ne transaction a t a time.
•

O ne key design decision was

ro

i n c l u d e a n i nd e x i n g

a n d search e n g i n e a s a b a s i c component of t h e pro d 
uct. A lthough the database is often t h e centra l piece o f
a groupware product, a n i n d e x i n g a n d search engine
often plays a si m il a r r o l e t()r a WWW s i te . This deve l 
opment i s compl etely consistent with t h e p h i l osophy
of the W vV W- i n formation is l i n ked as needed , not
necess a r i l y fo l lowi n g any structure. D a tabase use i s
m o r e s u i ta b l e for i n formation objects that h a v e some
u n i form ity i n their defi nitions.
The basic function of the indexing engine i s to map
a set of words to a d o c u m e n t c o n ta i n i n g t hose word s .
72

Di�it.1 l Tec h nical Journ a l

Vol . 8 No. 3

S h o u l d t here be arbi trary fl e x i b i l i ty

1 11

d e fi n i ng

gro ups ( i n c l u d i n g nesti n g ) >

Indexing a n d Search: The Way of the Future ?

1 99 6

On the o t h e r h a n d , users h a v e stated that they do
not l i ke products in w h i c h access control operations
arc c o m p l e x , especially i n the case of a prod u c t that
is s u pposed to help people co l l a bor:nc . I n a majority
of sce n a ri os , they argue that very l i ttle access control
is need e d .

f o r t h i s reaso n , w e tried to stri ke a b a l a n c e between

ad m i n istrators' needs and users' prdcrences. Although
vve recognize the i mportance of access control , we did
not give it precede n ce over prod u c t usabi l i ty. S i nce
usabi l i ty was o u r priori ty, a n d the time avai l a b l e to

work on it was l i m i ted, we d ivided o u r e fTorts between

the future as long as it makes management of access

making access control flexibl e a n d choosing defa u l t

control policies easier.

options t h a t would promote collaborati o n .
vVe defined access control tor the whole database

Futu re D i rections

( foru m ) , rather than for individual entries and attrib
u tes of entries. However, some entry-level access con

To date, we have received encou raging feedback from

trol is necessary. For example, it is preferable to l e t only

users. Of the ways tha t we can continue to improve

the owner ( o r the creator) of a n e n try modify and

the Alta Vista Foru m product, we fee l the tollovving

delete that entry. As a resu lt, we allowed the group def

deserve the h i ghest priority.

inition to include entry-specific logical users, rather

First, we need to provide better ways to help users

than provide a general mechanism for entry-level access

deal with i n formation overflow. Although we have

contro l . Therefore, a group may contain a member

b u i l t ways to tllter and search information into o u r

who is the owner of the current entry. D uring access

application, further simpli tlcation i s necessary. We

control checking, the cu rrent entry's owner is looked

are working on smart agents that brin g the relevant

up and matched against the c u rrently logge d - i n user.

information to the user's fingertips .

Instead of letting the administrator defi n e access

Second, a n umber of the functions that we provide

control for each possi ble incoming access/action, our

can be more easily performed on the client machine.

framework allows the application defi n ition to group

The Java language is the best candidate tor providi n g

accesses together into logica l access rights. For exam 

these functions since it enables us to handle a wide

ple, for the discussion application , we defined the fol 

variety of client platforms. I nitially, we arc looking i n to

lowing access rights:

using Java to improve certain user interface problems,

•

Read -Includes all read U RLs ( d i frerent v1ews,
whether for a single entry or a l ist of entries)

•
•

•

machine to notifY users of new information.
Third,

synchronous

collaboration

using

video,

Conni b u te-lncludes adcling a topic or reply

audio, and whiteboard will soon become feasible a n d
us

Modi r)r-l n c l u des any form of modification or

cost effective. I t is important tor

deletion

together through both sync hronous and asynchro·

Moderate-Includes such functions as creating key

nous methods of collaboration. For example, users

words, polling options, controUing n u m ber of levels
of replies, and setting certain entries as hidden
•

such as opening additional windows on the client

Administrate-Change access control or other
kinds of resource consu mption policies

By defi ning these access rights, the administrator only

to help bring users

should be a ble to use the calendar application to
schedu l e a meeting over the I nternet, and Windows
should be available to the user a u tomatical ly.
Fourth, as the AltaVista Forum software matures,
we hope to add to its performance and increase
its scalability. As its environment evolves, we are look

needs to estab lish who can do these five operations,

ing i n to ways to bypass the CGI interrace and usc a

rather than define nu merous other kinds of opera

compiled l anguage tor more of the toolkit implemen

tions. I t is still possible to c hange and add to this

tation . We also hope to add support tor l a rge commer

gro u p of access rights by making sim ple modifications

cial databases.

to the appl ication definition.

Finally, we wi ll continue to add innovative applica

O u r basic strategy for making access control easy to

tions to o u r produ c t . We recently built a prototype of

manage is to set up defa u lt policies of access control

a customer-support application that keeps track of

that apply to as many situations as possible, within rea

problem reporting. We are looking into other applica

son. The deEmlt policy is added to the appl ication def

tions such as project management, group review, and

inition. I f the administrator is satistled with the defa u l t

survey and decision-support systems.

pol icies, t h e n the access control can b e u s e d a s sup
pl ied . For the discussion application, the defa u l t policy

Acknowledgments

is the following:
We wish to thank the AltaVista Forum development

•

Read -Al l users, including a nonymous

•

Contribute-All users, excl u d ing anonymous

•

Mod i r)r-Owner ( c reator) of e n try and moderators

for h is leadership in starting the effort; Ra l p h DeMent,

•

Moderate-Owner of the forum

Bob Travis, David Marques, a nd Rick Fran.kosky, who

•

Administrate-Owner of the forum
To simplir)r implementation , we chose not to a llow

nesting of groups. Our design allows tor adding it in

and management teams for t heir contri butions to the
product. In particular, we wish to thank Peter H u rley

have worked with us throughout the l i fe time of the
produ c t and with whom we have devel oped a special
camaraderie; and D a n Kalikow, who was the fi rst
adopter and has cheered us on ever since.

Digital Technical Journal

Vol . 8 No. 3

1 996

73

References and Notes
1 . D EC �otes is a d i sc u ssion ;l p p l i carion r u nning p r i ma ri h·
on VAX svs re m s connected on a [) 1 T n e t network. Sti l l a
,· c r v

pop u l a r ro o\ w i r h i n D i gi ta l , it is used r(x c o l l a borat

i n g o n many top ics , r:m gi n g ri·om p rod u c t developmem,

cus to m e r support, and

m a rk et i n g

to various person;l[

i nt e n:st topics.

2. The prod uct was ori g i tl a l l v c a l l e d Wor k g ro u p Web
Foru m . It was su bseq u e n r l y mngcd i n to a l a rger tJ m i \ ,·

o r· produ cts a n d t h e prod u c r n a n K b e c a m e Al ta V ista
Fo r u m .

3 . F or tnorc i n fo r n1 a tion on th e Wo rld \Vide ·we b Consor

ri um/M I T La bo r a tor v r()l· Com p u ter S c i e nce Wo rkshop

on the World Wide Web and Colbborarion held Scp
r t: m b e r 1 1 - 1 2 , 1 99 5 , sec h rrp:/jwww.\\' 3 . org/pu b/

W W W/Col l a borati on .
4.

O usr er hou t , Tel a n d the Tk 7 ()()//d! ( Read i n g , Mass . :

J.

Addison - Weslev P u b l is h i n g Com p;l l J I', 1 99 4 ) .

S.

6.

U 4 .) BSn r u ix l 'm.� J W I I I I I i l li{, . \ fm z ual Nej�
ere nee G'u ide ( U n i ,nsirv of ( :., l i r( n n i a , B c r k c lc \ ·, ! 986 l .
.

\ 0/J. t tr.
'

During this rime, ) ;wa wa s sri \ \ o n rh c dra,,·ing board, o r ;lt
lcasr nor gene�·a \lv supported b,· Web bro11'Sers. We did

c \pccr ro usc Ja,·a ro e n h a nce o u r user i mc r fJ c c 01-er r i m e .

7 . For access t o D i gi t ;l \ 's i n d n i n g .l l l d search c n gi tH.: ,
visit r h c Al taVista Web si re

ar

h rr p : //cl l tavista. softwat·e.

d i gi tc1 \ .com .

Biograph ies

Dah Ming Chiu
] ) ;l h i'vl i n g Ch i u

,,·as a c on s u l t i n g e n g i n e e r i n Digita l 's
I merncr Software B u s i n ess U ni t- elm(\ r e c h n i ca l leadet· i n
de,·clopi n g rhe Alta Vis tel F or u m grmqm c1rc prod uct fo r the

I n re m e r . B ctore that proj ect , h e worked r(Jt· rh e Nen,·orks

At·c h i rccture G rou p on co n gesti o n c1 11d rlow control , n c r 
work m o n i toring, n a m e serv i c e , a n d the X . S O O sta n dard .

Prc,·ious to r ha r, he worked on p c r rimna n cc modeling

and ;mc1 l ysi s nen,·ork p ro toc ol s ;wd gr;1phic1 l workstation
de si c:n . D c1 h :\'l i n g is c u r rc nrh· ,lll cl rc h i tecr in tbc I n te rn e t
:
Sol t t i ons Group �f S u n M i c t os,·s rems, I n c . He recei,·ed a

;

P h . D . in c1 pplied ma r hc m cu i cs

( 1 98 0 )

ri-om H c1 n·a rd U n i 

\ c t·sit\' cmd a B . S c . i n e l ectrical e n g i n e e ri n g I 1 9 7 5 ) fro m

rhe l t ; lpcrial Col lege, Lo ndon U n i ,nsit\'. H e h o l ds th ree

pare 1 1 ts in th e at·eas of co nge s ti on con rml a 1 1 d 11em·ork

m o n i tori n g and i s a coauthor of Netu ·ork Jlo n itoriug

1�\jJ/o i11ed.

74

D i � i l .l l Tcclm ic1l journal

Vol . 8 No. 3

1 996

David M. G riffin

l )a\ e (; ri ni n J O i n ed D i gi ta l i n

1 98 1 . H e

is a p r i n c i p a l sofr

,,·are e n gi n e e r in rhe A l raVist,\ C o l l a bora t i o n En gi n ee r i n g

G ro u p , \\' here he leads t h e A l ta Vi st.l Forum Tool ki t te cl lll
t()r \ cr s i o n 3 . 0 . Da,·e a l s o l ed rhc roo l k i r tum r()r ,.L'rsion
2 . 0 and was r h e primarv designer ;llld i m plen1 c n tc r o f
the ( Workgroup 'We b Foru m ) version J . 0 too l kit a n d rhc
;l l t th or o f r h c doc u mcm- s h a ri n g cl pp l i ca r ion for 1 \: r s ion
1 . 0 . Pri or ro t h i s \\'Ork, Dave led th e J ) E C : d n s s e r\ ' LT p roj 
ect ( 11an o f t he DECnerjOS! prog ra m ) a n d design e d
a n d i m p l e m e nted the h i c rarc h i u l c e l l s cmd c e \ 1 - renarn i n g
lcK i l i r i cs i n t h e DCE C e l l Direcron Se n i c c . H e has been
i ll \ ohcd i n tlK d e ,·c lo pm e n r o f .1 n u m b c r o f d i :,tri b u ted
i tl tcmllc:rjo
S):.;fcms ( December 1 99 5 ) .

J.

Rose, a n d T . Spooner, "The

Ek ctrom i l,' I'" Proceedings o/
the 13rd Omji:rence of the Societ vfor Tech n ical
CiJI I 7 111 1 1 1 l icalion ( M ay 1 996 ) .

W. 13ow h i l l , "A 300M Hz CMOS JUSC M icroprocessor,"
1/:l-:Fjou mal o/Solid Stale Cirw its ( No1·em bcr 1 9 9 5 ) .

C. Bre nc h , " M o d e l e d J n d iYicrks," !U:F lnjuculll '96 Proceedings o/

/)ocumenlo I ion ( f�brua r1· 1 996 ) .

K . G e h l e r t c\ lld D . S c i p i o ne , " I n Situ Mon itoring: o f

J)rod u c r \Vlll:n, ," Solid Stale Tech nolo,'..!, I ' 1 1\ brch 1 996 ) .

!be I 5th A 1 1 1 1 / tUI OJI/fen:nce 0/ the TF.F.F Computa and

) . Grodstc i n , E.

A . C :h c\1'1\\', "Tirne,c\ le Analysis for Explicit Rate A l location

aided f)es�-..: u ( N o1·e1nber 1 9 95 ) .

Conl l l l l t l l icat ions Sociel ies ( f,t\arch l 996 ) .

in ATM Ncr�Vorks," 1/:f:.L lnjucom 96· Proceedings o/

Leh m a n , H . H a rkness, and Y. Wata nabe,

" l . o!!;ic Decompo�ition D u r i n g Tec h nolo f!0 Mappi ng,"

/l: F />;IC.JI /u /ernmio nol Co nference 011 OmljJitler

the J '5th A 1 1 1 11W/ Co n/erence q/ the //:;'/:;£ Computa and
Co rm n 1 1 1 1 icalions Societ ies ( March 1 996 ) .

P . Gronowski, "A 4 3 3 M H z 6 4 b QuJd - i ssue !USC

J . C l e me n t, " l'u lsed -currcnr Duty Cycle Dependence of

Solid Stale Circu its Conference ( Fe br u a r)' 1 9 96 ) .

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.
l'r;Ktical l mp l c m c nta r i o n M e t hods a n d Circ u i t E x a m p l e �

Elccrronic License Distri bu ti o n , " c llapter 10 in Jnte

( J u n e 1 99 6 ) .

the 1-i!l l rlh lntemalional Sr1 1 1posium on 111/(�!.!, mled

M e rhodolo).!;l tix PSG and PETEOS f i l rns in a H ighl1·

E lccrromi�rc\ti o n - i n du ced Stress Gener:1tion i n A l u m i n u m

T Co l l i ns, "PO LYC :ENTER Li cense Syste m : Enabling

gmted Netu •od! Mwwge111e111 V Procf:'edin/.;:s o/

Used on rhe Al ph :1 2 1 1 64 , " \- 'LSI Circ u its .�J'/1/jJosiu m
E.

;\'et uwf..: , \Ita l lt!,f.!, C:111Ci l l ( London : C ll Jp!llclll & H ;� l l ,

H ;\ mo n

c1 11d H . Wood�Vard, " P rocess C o n trol

1 n l l T;l Lri l·e :Vi u l (i p rocess CVD S1·stcm," Adt ·o u ced Semi

J S R "\ 0- 4 ! 2 7 1 - S 7 0-il, l 9 9 S ) .

conductor . \ Itt n t t/itcl l l l ing Co nfere uce and Win l'sbop

T. Col l i n s, "The Wolf a s a Metaphor for Sohware Age n t , "

( !\! me m be r 1 9 'J 5 ) .

A . Con n , "Time A ft(mia nce s: The Time Factor i n Diag

f)el 'ices

c h a pter ti1·e i n !Jots wul Internet fleasties ( I nd i a napolis,

I nd . Sams . net P u h l i s h i n g , ISBI' l - 575 2 1 - 0 1 6 -9, 1 996 ).

nostic l \.1 b i l ity Heuris tics," J-Ju nwn Faclors in C:u lllplll
in,r,;. O-ff '() 5 Proceeclin,r,;s ( i\IL\y 1 99 S ) .

Z. C1·etc1novic, " Per·fmmance Characterization of the

Alp he< 2 1 1 64 M i cr oproce ss or Using TP and S P EC \tVo r k 
loads," J>roceedings (�j'the IF.Hf:. Second !ntenwtion(f/

S) •mpusitun on H(u, h-pelj(Jrnnmce Co mputer
A rchilec/l!re ( h bruc\rv 1 9 9 6 ) .
M . Desa i , R . Cvijcti c , a n d

J . Je n se n , "Sizing o f Cl oc k

Con/('reuce (J u m: 1 99 6 ) .

M . Desai a n d Y. Ye n , "A S1·stcmatic Tec hniq u e tor Veri t\• 

i n g Critical P' ll:T:F Transactions 0 1 1 !:lec/twt

l 996 ).

H. ) a kieiJ, "Performance Visua l i zation of a Distri buted

Sys 1 c rn : A Case Studv, " Co mp u ter ( N o 1-e rn ber l 995 ) .

R . Kelsey, " H Jd h xes, Change Speci ri c a tions c1 nd Li n

gui�ric C : on s r r:1 i n ts or\ l'roblem D i c1gnosis," Sojil l 'ore
�:·n,f.!, ineen·l l,f.!, i\'olf!S ( M arch 1 996 ) .

Ke rn , "The C h icke n i s l rwoh·ed, .But the Pig i s Com 

m i t te d - B u i l d i n g Com m i tment Throu gh C Jscad i n g

Distri b u tion Ne rll'orks ror H i g h Performance CPU

Digit.l l Tcch nic11 )ou rn:ll

Hucmg,
j b r ice l l i , � . Kh a l i l , a n d R. Rio�, "An
c
Accurate c.;,, te Lc mnh L \ traction M e thod for S u b - 4 u arrn

C : . - L.

j.

Ch ip�," J>mceedin,f.!,S o/ the 33rd Des(u,n A u tomation

76

L. El l i o rr, R . S h u m a n ,

S l '/ 1/f}().\ittlll Pmceedings ( Apri l 1 99 5 ) .

Kno\\'ledge- based Performance

C. Bouti n , " h·om M�1 n a g er

Srmpos i1 1 111 (Apri 1 1 99 6 ) .

Tu n�stcn

Tu ni ng A(h-isor," (Jf(;CJ"i. Proceedings o/ the 2 lsi
�\

a n d C :nritication , " ret/: 34th A n n ual Spring Reliu hilil l '

1996

· rcc\11\s," (>uolity Prugress ( October 1 9 9 5 ) .

� . Klu l i l ,

F a rice l l i , J n d

H uang, "Two - d i mensional

Dopc1 1 1 t Prolili n g ofSubrnicron MOSFETs Usi n g N o n l in<.:'! <)6 ( J u ne 1 996 ) .
"C

B . i'vl i rm J n ,

t()r Thernnlh· Lo:�ded

W . Nagorski , W. M c G e e , E . Picciol i , and L Gair, "A u ra 
marie Test C : h i p Documcnrarion S y n th es i s , " l 'rncel.'din,r.;s
uj' the I 99o 1/J;F luternational Con)c'rc'nce on Micro
electml l ic 'fi'st Structu res ( March

A . Villani and H . Ngu,·cn, "Corre lation of rhe Mechanical
ro the ThcrnlJI S t re n g th of Ceramic Packages," A merfC(/ 1 /
Cera m ic Societ ) ' Ti·m,soclions: 1-lrhrid Microcleclr o n ic
Malt>rials ( �o,·embcr 1 994 ) .
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Study," Cl fG'95. Pmceedinp,s of !be 2 1st A n n uc!l Co n 

ferencej (Jr rlw Neso1 1 rcl! M a na,r.;emenl a n d Pe1jcm1 1 a n c e EL•aluation ojLnterprisc Co mp u ting Srstems

( Decem ber 1 99 5 ) .

1 99 6 ) .

L . N o o1 c k J n d M . Kantrowitz, " I 'm Done S i m u l ;uing;
No11·

Wh,ul Verification Co,·erage ArLl l vs i s and C :or
Checking of the DFCchip 2 l \ 64 A l plu

l·ecnh.:ss

M ic:roprocessor," Proceedings of the 33rd /)es!gn

A uti!II ICII ion Co nfe re n ce ( J une

1 996 ).

0. 1\;l iJl,l b i , " A(bpti,·e Absorbi n g BoundarY C o n di ti o n s

in Fi n i te - d i ftl: renc e T i m e Dom a i n Applio tions t(>r E M C
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·

0 . lbmahi ct a \ . , " Dynamic An;llvsis of V ·rr-,lllsmission

Li nes," Conference Proceedings oj' lhe I 2lh A n n ual

Ncl 'ieu· ofPm,r.;rcss in Applied Computolionol
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1 99 6 ) .

S . Rege, "A Distri buted Svstem Cl i e nt/S e r v e r Arc h i tecture
t(lr .l n teracri,·e M u l timedia Applications," C0. \ 11'96 Digest
q/l'ojJeJ :,· · i lsi IFFI:' Computer Society In len w I iono I

Confi·rence ( rcbru ar\' I 996 ) .

R . Ri os , � - A ro r a, C : . - L . H uang, :--.J . Kl d i l , ) . 1-'arice l l i ,
a n d L. Gr u b e r, "A Physical Comp;lCt .v! OSJ-'ET M o de l ,
l 11 c l u d i n g Quantum 1Vlechanical E ffc crs , for Statistical
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.

K.

Rose l l e ,

" E st i rn :� r i n g Crossta l k i n M u l ticonductor
fj nes," !EhF Tt"(l /1Sclclious on Components.

Tra nsmission

Pod�o.r.; ing and Mmwfac/urinp, 7 e
' ch7! olog ) ' f'o rl /3:
A dm u ccd Packa,r.; in,r.;

� - R u bi n ,

( M ay 1 996 ) .

" Efticienr Instruction Sc h ed u l i n g

Usi ng h n i te

SrJte A u ronu t,1 , " Procecdinp,s o/ lhi! 28/h A n n uol
lu!crurtlioual .S)'I IIposi/ 1 111 0 1 1 .l licmorch itecluu·
( �m·c n 1 ber

l 99S ) .

C. S m i th c1 11d T . Val l one, "Men rming: P ro , · i d i n g Profcs
_, ion:�l and Organi zational Benetirs," f'mu'('(lin,r.;s u/
tlw 1,-!rd Cnuference

ol tbe Societ ) 'ji!l· 'lh'h u icol

Com l ln l l l icotion ( M a1·

1 99 6 ) .

N . S u l livan, S . Dass, G . P o ll a rd , W . Jones, ,1nd ·r. Linds:�y,
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Ci'l'rlin,r.;s o/ the Society qjPhoto-Opt leal Ins! m men/a

t io n l:n,!!, ineel:,· ( l'cbruarv

1 99 5 ) .

H . kq!,a n , " Distributed Performance Monitor U s i n g

S N M I' V 2 , " I!:F!:/!HP Net/l 'ork Opemtions u u d M(.//1ll,l'.I'IIWIIt S i 'l l lfJOSi/ 1 111

( April I 994 ) .

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ti·o1n Mod uks-on- Backplane Con ti g. u r.1ti o n s , " ll:l:F

'f i w !soelions

on

Electronwgnetic Coll lp(ltfhilil l '

(August 1 99 5 ) .
Digi tJI Tc( h n i (J I j o u nL\1

Vol . 8 N o . 3

1 9') 6

77

I

Recent Digita l
U . S. Patents

Eq u i pment Corpora tio n . Titles and names s u p p l ied

The r( >llowi ng patents were rece n tly issued to D igital
to u s b�' the U . S . Patent and Trademark: Ofnce arc

reprod uced as the\' a p pear on the origi n a l published
pate n t .

1)3 5 3 )\ 0 0

5 , 3 7 1 ,807
5,37 1 ,822

5 ,3 7 1 ,868

5 , 3 7 1 ,870

M . S. Lc11·is, L. A . Tn:scder, R . M. Tu slcr,
;llld C . Slllcb

M o d u b r E n c l osure tor Electronic Eq ui pment

r:. H or\\ i tz and E . Thomson

Rcgistn Method and Appar·atus for 'TC\t C: bssitlcation

1\' . Ka n n a n ;md 1\tl . S .

C. 1'. Ko nig, H. S. Y:lng, and vV. H a11 c

I'. M . Goodll'in, D . Smelser, and

Method of Pack.l !,'.ing and Asse m b l i n g Opto-e lectron i c
l nrcgran:d C i rc u i ts
M e thod and App;li·

fiber Optic
;l

Track-and

5 , 3 8 2 ,8 3 1

B . Lee, E . At:� ko v, and J . Clement

I nte grated Circ u it l'vletal Film Interconnect H a1·i n g

5 ,3 8 3 ,096

M . C. Benson a n d L. M . M a zzon e

l/0

5 ,384,779

M . Patrick a n d J . A. D a l y

State Machines for Con figura ti o n of a Com m u nications

E nh a nc ed Resistance to Ele c rro m ig ration
E x pan sio n Box

Network

5,385,289

C. Bloc h, P. McKi nley, a n d R . Ra ng an a tha n

5 , 3 8 5 ,630

A. P h i l i possian, H . So le i ma n i , and B. Doyle

Embedded Featu res for Registration Measurement i n
E l e ct ro n i c s M a n u tac r u rin g

Proc ess to r I n c rea s ing Sacrificial Oxide Erc h lbtc

to

Red u c e Field Oxide Loss

5,386,5 1 4

V. Boacn , R. Lary, B . Rubinson, D . Th i e l ,
C . Van l ngcn, W. Warson, R . Willard, and

Q ue ue Ap para t u s a n d Mcch�nics tor
I n t e rfa ce Arch itecture

a

C o m m u n i cat i ons

E . A . G a rd ner

5 ,386,5 2 3
5 ,386,524

Ad d ress i n g Sc h e me for A ccess ing a Portion of ,l

N. A . Croo k , M. ]. Se a m an, a n d
D . L . A . B rash

La r ge M e mory Space

V. Bo a en , R. La r y, B. Rubinson, D. Thiel ,

S y s re m for Accessing Information in a Data P mc e ssi ng

C . Van I nge n, W. Warso n , and R . W i l l ard

Sy s re m

J. C. K. Lee, M . C as tro , F. Tu ng , C. Lee,

S e q u e nti a l M u l ti l a)'t:r Process for Using f l u orin a ted

a n d A. A h mad

Hydrocarbons as a Dielectric

5 ,387,530

A . P h ili p ossi a n and B. Doyle

Th rc sho l. d Opt i m i z at i on For SOl Tran sistors t h rou g h Usc

5,388 ,099

N. Poole

5 ,387,495

5 ,3 8 8 , 2 2 2

of N e g a t i v e Ch:trge in the Gate O x i de

Ba ckpl an e Wiring to r H ub in Packer Data

Comm Lt ni c a ti ons Svstem

L . A . P. C h isv i n ,

J. F. Ranta l a , J .

K. Groo m s ,

M e m ory Subsystem I nput Queue

and D. W. Hartwell

5 ,388,224

B . JY!Jskas

Processor Identification M eclunism for a Mult i processor

S y s te m

5,388,247

P. Goodwi n , K. T h a l l er, a n d B. M a s k a s

H isrorv Bu ffer Contml to Reduce Unnecessarv AJ i oca ri ons
i n a M emo ry Srream Bufkr

5,388,263

R. K. Peterson , ] . R .

5 ,389,757

E. Soul ierc

5 ,390, 1 73

E l l i s , a nd C. G . Nv l and e r

Pr o c ess ors

Ela s rom c r ic Ke y S wi tc h Act u a to r

B. Spinncv, R . Si m c oe , G. Varchese, and
R. . T h o m a s

5 ,390,286

Proced u re State Descri p tor S yste m tor Digital D a ra

K. K. Ra m a kri s h n a n

Packer Format in Hub tor Packet Data C o m m u n i c at io n s

S y ste m

Reti cular Discri m i nation N e twork

for Spe c i t),i n g

Re a l - time

Co n di t io n s

5,390,299

S . L. Rege, K . K . Ramakri s h n a n , and
D. A. Ga g ne

S ystem tor Using Th re e Diffe rent Methods ro Report
B u ffe r Memory Occupancv I n formation Regard ing
F u II ness- rel a ted :llld/or Packer Discard - rclarcd

I n formation

5 ,390,302
5 ,390,3 1 8

].

Joh nson , M . Ho we l l , and C. W h itak er

K. K. Ra m a k ri s h n an and P. Bi sw as

Transaction Control
C ac h e A rra n ge me n t for File System in Digir�l D�ta
P r o cess ing Sys te m

Method tor O n - l i ne Re org ani za t i on ofrhc D:tta o n a
RAI D -4 or IW D - 5 A1TJV in r h e Absence of One Disk
a n d r h e O n -line Resrorarion of a Rep b c em e nt D is k

5 ,390,327

C. Lubbers and D . Thiel

5 ,392 , 2 1 9

S . Birc h , G. Gavrel, and Z . Memon

Dcte r m i nation of l nterconm:ct S t re ss Test Current

5 ,394 , 1 4 3

J. M u 1-ra y and G . A n r os h en k ov

R u n - l en gt h C o m p re ss io n of I n dex Kcvs

5 ,394,347

R. !(i ra, S. Tremblay, and T. Lynch

5 ,394,401

M . Patrick and

5 ,394,5 2 9

].

J.

A . Daly

Brown , J . M ey e r, and S . Persels

Method and Apparatus tor G e n e ra tin g Tesrs for Stru ctures

E x pressed as E xten de d Finite Srate Machines

Arrangement tor a Token Ri ng Com m u nications Network

Branch Prediction Unit tor High -performance Processor
Vol . 8 No. 3

1 996

79

Call for Papers
Networl( Products
and Technologies
The Digital Techuicctl .fou rnal seeks technical papers i n a l l areas of networki ng
tec hnol ogy tor an issue to be pu blished in the fal l of 1 997. Digital's engin eers and
ind ustry p:trtners interested i n participating in the special issue shou ld send topics
and brief abstracts ( 1 0 0 words) by February 10, 1 9 97, to
Jane B l ake ,

Managing Editor

Dil; itctl Tech n ical]ou rna!

Digital Equipment Corporation
5 0 Nagog Park, AK0 2 - 3/B3
Acton, MA 0 1 72 0-9843
Email : jane.bl ake@ljo.dec . com
508-486-25 44

Notice of the topics accepted will be sent to all authors by February
The man uscri pt-sub mission d at e t(x accepted topics is M:ty 30, 1 997.

2 8 , 1 997.

for i n ti: mn a ti o n on topics published in the Jo u rnal. the audience, writing guide
lines, and the peer-review process, see Imp :/jwww.d i gital.com/i ntC"J/dtj/
dtj -guide. htm or contact the Managing Ed itor at the add ress above .

ISSN 0898 - 9 0 1 X
Printed i n U .S.A. E C-N72 8 5 - 1 8j96

12

1 4 2 l . S Copyright © Digital Equipment Corporation

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Digital Technical Journal, Volume 8, Number 3 Dtj_v08 03_1996 Dtj V08 03 1996

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