Table Of ContentATM Switches
Edwin R. Coover
Artech House
Boston • London
LibraryofCongressCataloging-in-PublicationData
Coover,EdwinR.,1942–
ATMswitches/EdwinR.Coover.
p. cm.
Includesbibliographicalreferencesandindex.
ISBN0-89006-783-X(alk.paper)
1.Asynchronoustransfermode. I.Title.
TK5105.35.C66 1997
004.6’6—dc21 97-12575
CIP
BritishLibraryCataloguinginPublicationData
Coover,EdwinR.
ATMswitches
1. Asynchronoustransfermode
I.Title.
621.3’8216
ISBN0-89006-783-X
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Contents
Preface ix
Acknowledgments xx
Chapter1 Introduction 1
1.1 Why ATM? 1
1.2 TheState of theStandard 3
1.3 ATMConstituenciesToday 5
1.4 Sources,Sinks,andthe Future 8
Chapter2 TheATM Standard 11
2.1 Cells 12
2.2 A LayeredProtocol 12
2.3 ClassesofService 13
2.4 Signaling 15
2.5 CallsandConnections 15
2.6 Connection-oriented 16
2.7 Traffic Types 17
2.8 ATMAdaptationLayers (AAL) 17
2.8.1 AAL1 18
2.8.2 AAL2 19
2.8.3 AAL3/4 19
2.8.4 AAL5 19
2.9 Addressing 20
2.10 NetworkInterfaces 21
2.11 Summary 23
Chapter3 TheTechnicalChallengesof High-SpeedSwitchingI 25
3.1 InteroperabilityWithLegacySystems 25
3.2 Makinga Connection 28
v
vi ATMSwitches
3.3 Multiplexing andDemultiplexing 31
3.4 Error Control 34
3.5 Latency 36
3.6 Data Packaging 36
3.7 Performance 37
3.8 Sequencing 38
3.9 Buffers andBuffering 39
3.10 Queues 40
3.11 CongestionControlandFlow Control 41
3.12 Summary 47
Chapter4 TheTechnicalChallengesof High-SpeedSwitchingII 49
4.1 Compression 49
4.2 Cost 50
4.3 Management 51
4.4 ProtocolsandProtocol Processing 54
4.5 Classof Service 56
4.6 Security 58
4.7 Fault Tolerance 60
4.8 Chargeback 62
4.9 SynchronizationandTiming 63
4.10 Summary 64
Chapter5 CommercialATMProducts 67
5.1 Prestandard 67
5.2 NetworkInterface Cards(NICs) 68
5.3 Plain Creative Marketing 69
5.4 TheManagement Shortfall 69
5.5 YourMileageWill Vary 76
5.6 TheLegacyoftheLegacy 77
5.7 Presentism 77
5.8 Today’sSwitchingVendors 78
5.9 ATMSwitch Overview 81
5.10 Summary 81
Chapter6 ATMLANSwitches 89
6.1 FourApproachesto Legacy LANs 92
6.2 ForeSystems 93
6.3 TheVirtualLANApproach 94
6.4 THeASX-200WG (For Workgroup) ATMSwitch 98
6.5 ForeThought 101
6.6 CiscoCorporation 107
6.7 Cisco’sLightstream1010WorkgroupSwitch 109
vii
6.8 CiscoHardware 109
6.9 CiscoSoftware 110
6.10 Summary 112
Chapter7 ATMAccessor“Edge”Switches 115
7.1 CascadeCommunicationsCorporation 116
7.2 Cascade’sB-STDX9000SwitchFamily 117
7.3 B-STDXATMMode 120
7.4 B-STDXFRMode 121
7.5 B-STDXSMDSMode 122
7.6 Newbridge Networks Corporation 123
7.7 Newbridge 36150AccessSwitch 125
7.8 Summary 129
Chapter8 ATMWANAccessProducts 131
8.1 ATMCSUs/DSUs 132
8.2 ATMInverse Multiplexers(AIMs) 132
8.3 ATMService Multiplexers 133
8.4 ADCKentrox 133
8.5 ADCKentroxDatasmartT3 ATMData Service
UNIT(ADSU) 144
8.6 ADCKentroxT1/E1 ATMAccessConcentrator
(AAC-1) 144
8.7 ADCKentroxMultismartSNMP Agency(MSA) 145
8.8 Digital Link Corporation 147
8.9 DL3200SMDS/ATMDigital Service Interface 148
8.10 W/ATMPremisewayATMService Access
Multiplexer 149
8.11 Summary 152
Chapter9 Large ATMSwitches 155
9.1 NortelandtheMagellanFamily 156
9.2 Voice Networking 157
9.3 MagellanMultiplePriority System(MPS) 160
9.4 Nortel’sConcorde ATMSwitch 162
9.5 FujitsuCorporation 165
9.6 Fujitsu’sFETEX-150 ESP 166
9.7 DesignObjectives 166
9.8 TechnicalDescription 168
9.9 Marketing theFETEX-150 170
9.10 Video Server/the North Carolina Information
Highway (NCIH) 170
9.11 Frame Relay/NYNEX 172
viii ATMSwitches
9.12 Cell Relay/BayNetworks 173
9.13 Summary 173
Chapter10 TheATMPrognosis 177
10.1 The“AnchorageAccord” 177
10.2 “Fast”Ethernet andthePromise of a
Gigabit Ethernet 178
10.3 Standards,theForum, andthe Marketplace 179
10.4 TheLonger Term 180
Bibliography 183
Glossary 239
About theAuthor 325
Index 327
Preface
Preface
From its inception, this volume has followed a twisted road. Originally
conceived as a book on one of several promising new broadband tech-
nologies, the appearance of at least a dozen books on the emerging asyn-
chronous transfer mode (ATM) standard clearly obviated that need. At
the same time, the introduction of commercial ATM switches and com-
ponents, and their peculiar interpretations and implementations of the
standard, prompted a reappraisal. What is going on here? Has ATM, the
much-touted “unification” technology, a single way of handling voice,
video, and computer data across conventional local area network/metro-
politan area networks/wide area network (LAN/MAN/WAN) boundaries,
beenhighjacked?
Itwouldseemso.First,anumberofsmallstartupcompaniessuchas
FORE and Lightstream charged on the scene with “prestandard” LAN
products. Their motto seems to be, “data can’t wait!”They, in turn,have
been followed by seemingly every company that produces time division
multiplexers (TDMs), routers, LAN hubs, packet orframe relay switches,
or central offices switches. The credo is that ATM is “The Next Big
Thing.”
The level of sheer hype on ATM makes even Microsoft’s Windows
95launchlook modest.DoesATMpresent“IntegrationTechnology AND
End-to-EndTechnology?”Isthehigh-speedATMnetworkthe“Backplane
of the Metacomputer?” Will ATM result in the “Death of Distance?” Not
very likely. Indeed, if anything, there is a bit of embarrassment on just
where allthis speed andeleganttechnology willbeputtouse.In thelan-
guageoftheindustry flak,thereis noacknowledged“killerapp”—a tech-
nology-enabled breakthrough application. Instead, there is a host of
contenders or perhaps pretenders: Lotus’ (now IBM) Notes, desktop
videoconferencing, distance learning,and various applicationsinvolving
compressedvideo.
ix
x ATMSwitches
TheATMmarketisagoldrush,completewithChaplinesqeaspects,
but mostly it is messy and wild. It is the most exciting technology since
the Ethernet. Were it not for the Ethernet precedent, one would be
temptedtoobservethattherearetoomanycompaniesforanyonetomake
any money; indeed, it may be just the beginning. Nonetheless, like most
goldrushes,manywillreturn(relatively)empty-handed.Lightstreamwas
bought by router Goliath Cisco Systems, who subsequently gobbled up
StrataCom.BBN’sATMswitchbecameAgileNetworks’ATMizer.Startup
Centillion Networks was acquired by Bay Networks, itself a merger of
WellfleetandSynOptics.Andjustbeforethisbookwenttopress,Cascade
wasacquiredbyAscend, afast-risingvendorofremote-accessproducts.
From the commercial product point of view—the view of this
work—it is the exciting story of when a promising technology meets the
magicofthemarketplace,andtheunexpectedhappens.
Acknowledgments
I have sometimes seen writing a book as a centripetal act in a centrifugal
universe. Over the four years I have been researching and writing this
one, the centripetal act has been much aided by the comments of col-
leagues (or ex-colleagues) at the MITRE Corporation. Rick Tibbs, Rob
Rice, Randy Mitchell, David Koester, Satish Chandra, Susmit Patel, Rich
Verjinski, Doug Bamford, and Tom Ramsay have influenced me on a
number of communications issues. Janet Park produced the figures and
tables, and they reflect her considerable skill and care. The staff at the
MITRElibrary,includingsomenowdeparted,providedtheresourcesand
an environment that enabled sustained investigation. They included
Sherri Lieberman, Vi Jefferson, Hugh Keleher, John Huddy, Win Kutz,
SheliaChatterjee,JeanWatson,andBelindaParker. Mark Walsh,acquisi-
tions editor at Artech House, has been both supportive and patient.
Artech staff Lisa Tomasello, Pamela Ahl, Beverly Cutter, Matt Gambino,
Kimberly Collignon, Julie Lovelock, Roberta de Avila, Alexia Rosoff,
Darrell Judd,Kate Feininger,andJudiStoneprovidedtimely adviceona
large span of issues and, in the process, averted some real howlers. Fi-
nally, I owe a considerable debt to an unknown outside reader who not
only caught a number of embarrassing errors, but whose witty marginal
comments backed me off from a number of judgments that appeared, in
retrospect,excessivelyexcathedra.
xi
Introduction
1
Introduction
1.1 WHY ATM?
One can identify three developments of the 1980s that impelled the de-
velopmentofhigh-speedswitching.
The first was the continuing mismatch between computer channel
speeds and the public transmission network. Twenty years ago it was
“MIPS talking to Kbps;” now, it is close to “GIPS talking to Mbps.” Al-
thoughthetransmissionnetworkscould,bymeansofseveraltiersofmul-
tiplexingand demultiplexing,partiallyaccommodate thistorrentofzeros
and ones, it was neither economical nor did it make sense intuitively to
multiplex and demultiplex bit streams whose end use was a high-band-
width device. To provide an example, a Cray supercomputer with a
100-Mbyte/s channel (800 Mbps) driving a graphics application would
havehadtobemuxedintomultipleDS-3(45Mbps)streamsandreassem-
bled. The costs of this sort of mismatch simply ensured that for such ap-
plications, the cheapest routewas usually to move the applicationto the
supercomputerorthesupercomputertotheapplication.
Theseconddevelopmentwasthewidespreaduseofgraphicalrepre-
sentation.Widelyusedas ameans ofvisualizationand/ordatareduction,
the bit streams (even when compressed) again starkly outlined the mis-
match between many graphical applications and an economic means to
remotely distributethem. Forexample, a megapixel display(800×1200)
using just 16-bit color graphics and employing only 15 updates per sec-
ond generates a 230.4-Mbps bit stream. Although this 230.4-Mbps bit
stream may (depending on the application’s requirements) be satisfacto-
rily compressible ontoa DS-1(1.544 Mbps) circuit,a leased DS-1facility
was often unjustifiable for a single high-bandwidth application; further,
the obvious lower cost alternative, dial-up DS-1, is not ubiquitously
available.
1
