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DATA COMMUNICATIONS NETWORKING DEVICES:
OPERATION,UTILIZATION AND LAN AND WAN INTERNETWORKING
Fourth Edition
Data Commun ication s Networkin g Devices:Operation ,Utilization an d LAN an d WAN In tern etworkin g,FourthEdition
Gilbert Held
Copyright #2001John Wiley &Sons Ltd
ISBNs: 0-471-97515-X (Paper); 0-470-84182-6 (Electronic)
DATA COMMUNICATIONS NETWORKING DEVICES: OPERATION,UTILIZATION AND LAN AND WAN
INTERNETWORKING
Fourth Edition
Gilbert Held
4-Degree Consulting
Macon,Georgia
USA
JOHN WILEY&SONS Chichester.New York.Weinheim.Brisbane.Singapore.Toronto
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Libaray of Congress Cataloging-in-Publication Data
Held,Gilbert,1943±
Data communications networking devices:operation,utilization,
and LAN and WAN internetworking/Gilbert Held.D4th ed.
p.cm.
Includes index.
ISBN0-471-97515-X(alk.paper)
https://www.wendangku.net/doc/eb14074815.html,puter networks.
https://www.wendangku.net/doc/eb14074815.html,puter networksDEquipment and
supplies. 3.Data transmission systems.I.Title.
TK5105.5.H441998
004.6Ddc2198-27200
CIP
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN047197515-X
Typeset in10/12pt Imprint by Thomson Press(India)Ltd,New Delhi,India
Printed and bound in Great Britain by Bookcraft(Bath)Ltd
This book is printed on acid-free paper responsibly manufactured from sustainable forestry,in which at least two trees are planted for each one used for paper production.
To Beverly,Jonathan and Jessica
for their patience understanding and supportD
I love you all
To Dr Alexander Ioffe and family of MoscowDcon gratulation s on n ext year in Jerusalem bein g eachyear!
CONTENTS
Preface xxiii Acknowledgements xxv 1.Fundamental Wide Area Networking Concepts1 1.1Communications System Components2 1.2Line Connections2
Dedicated line2 Leased line2 Switched line3 Cost trends4 Factors to consider4 1.3Types of Services and Transmission Devices5
Digital repeaters6
Unipolar and bipolar signaling6
Other digital signaling methods7 Modems7
Signal conversion7 Acoustic couplers8
Signal conversion8 Analog facilities9
DDD9
WATS10
FX11
Leased lines13 Digital facilities14 Digital signaling14
Unipolar non-return to zero14
Unipolar return to zero16
Bipolar return to zero16 Evolution of service offerings17
AT&T offerings18
European offerings20
DSUs20 1.4Transmission Mode22
Simplex transmission22 Half-duplex transmission22 Full-duplex transmission23 Terminal and mainframe computer operations25
Different character displays26 1.5Transmission Techniques27
Asynchronous transmission27 Synchronous transmission29
1.6Types of Transmission30 1.7Line Structure31
Types of line structure31
Point-to-point32
Multipoint33 1.8Line Discipline33 1.9Network Topology35 1.10Transmission Rate36
Analog service36 Digital service37 1.11Transmission Codes38
Morse code39 Baudot code39 BCD code41 EBCDIC code42 ASCII code42 Extended ASCII43 Code conversion46 1.12Error Detection and Correction47
Asynchronous transmission48
Parity checking48
Block checking51 Synchronous transmission53
Cyclic codes54 1.13Standards Organizations,Activities and the OSI Reference Model58
National standards organizations59
ANSI59
EIA60
FIPS62
IEEE62
BSI62
CSA63 International standards organizations63
ITU63
ISO64 De facto standards64
AT&T compatibility67
Cross-licensed technology68
Bellcore68 Internet standards69 The ISO reference model70
Layered architecture71
OSI layers71
Dataˉow74 1.14The Physical Layer:Cables,Connectors,Plugs and Jacks75
DTE/DCE interfaces76
Connector overview77
RS-232-C/D79
RS-232-E89
RS-232/V.24limitations89
Differential signaling90
RS-44991
V.3593
RS-366-A93
X.21and X.2095
X.21bis98
RS-53098 High Speed Serial Interface100
Rationale for development100
Signal de?nitions101
Loopback circuits103
Pin assignments104
Applications105 High Performance Parallel Interface105
Transmission distance105
Operation106 Cables and connectors106
Twisted-pair cable107
Low-capacitance shielded cable107
Ribbon cable107
The RS-232null modem107
RS-232cabling tricks110 Plugs and jacks111
Connecting arrangements114
Permissive arrangement114
Fixed loss loop arrangement114
Programmable arrangement115
Telephone options115
Ordering the business line117 1.15The Data Link Layer117
Terminal and data link protocols118
Connection establishment and veri?cation118
Transmission sequence119
Error control119 Types of protocols120
Teletype protocols121
XMODEM protocol126
XMODEM/CRC protocol128
YMODEM and YMODEM batch protocols129
XMODEM-1K protocol132
YMODEM-G and YMODEM-G batch protocols132
ZMODEM133
Kermit134
Bisynchronous protocols136
DDCMP142
Bit-oriented protocols144
Other protocols151 1.16Integrated Services Digital Network151
Concept behind ISDN152 ISDN architecture152 Types of service153
Basic access153
Primary access157
Other channels157 Network characteristics158 Terminal equipment and network interfaces159
TE1159
TE2160
Terminal adapters160
NT1162
NT2163
Interfaces163 The future of ISDN164
Review Questions165
2.Wide Area Networks171 2.1Overview171
Transmission facilities172 2.2Circuit Switched Networks172
Frequency division multiplexing173
ITU FDM recommendations174 Time division multiplexing175
T-carrier evolution175
Channel banks176
T1multiplexer177 Circuit switching characteristics178 2.3Leased Line Based Networks178
Types of leased lines179 Utilization examples179
Multiplexer utilization180
Router utilization182 2.4Packet Switching Networks183
Multiplexing as opposed to packet switching183 Packet network construction184 ITU packet network recommendations184 The PDN and value-added networks185 Packet network architecture186
Datagram packet networks186
Virtual circuit packet networks187 Packet formation187 X.25188
Packet format and content188
Call establishment190
Flow control191 Advantages of PDNs191
Technological advances191 Packet network delay problems192 Fast packet switching193 Frame relay194
Comparison to X.25194
Utilization195
Operation196
Cost199
Voice over frame relay200 2.5The Internet201
TCP/IP202
Protocol development202
The TCP/IP structure202
Datagrams versus virtual circuits205
ICMP and ARP208 The TCP header208
Source and destination port?elds209
Sequence?eld210
Control?eldˉags210
Window?eld211
Checksum?eld211
Urgent pointer?eld211
TCP transmission sequence example211 The UDP header213
Source and destination port?elds214
Length?eld214 The IP header214
Version?eld214
Header length and total length?elds215
Type of service?eld215
Identi?cation and fragment offset?elds217
Time to live?eld217
Flags?eld217
Protocol?eld217
Source and destination address?elds217 IP addressing218
Class A219
Class B219
Class C219
Host restrictions219 Subnetting219
Subnet masks220 Domain Name Service221
Name server223 TCP/IP con?guration224 IPv6226
Evolution226
Overview227
Addressing229
Migration issues233 2.6SNA and APPN235
SNA concepts235
SSCP236
Network nodes236
The physical unit236
The logical unit237
Multiple session capability237 SNA network structure237 Types of physical units239 Multiple domains239 SNA layers241
Physical and data link layers241
Path control layer241
Transmission control layer242
Dataˉow control services242
Presentation services layer242
Transaction service layer243 SNA developments243 SNA sessions244
LU-to-LU sessions244
Addressing244 Advanced Peer-to-Peer Networking(APPN)246
APPC concepts246
APPN architecture247
Operation248
Route selection250 2.7ATM251
Overview251
Cell size252
Bene?ts252 The ATM protocol stack255
ATM Adaptation Layer(AAL)255
The ATM Layer256
The Physical Layer257 ATM operation257
Components258
Network interfaces258
The ATM cell header259
ATM connections and cell switching262 Review Questions264 3.Local Area Networks269 3.1Overview269
Origin270 Comparison to WANs270
Geographic area270
Data transmission and error rates271
Ownership271
Regulation271
Data routing and topology272
Type of information carried272 Utilization bene?ts273
Peripheral sharing273
Common software access273
Electronic mail273
Gateway access to mainframes273 3.2Technological Characteristics274
Topology274
Loop274
Bus275
Ring275
Star275
Tree275
Mixed topologies276
Comparison of topologies276 Signaling methods277
Broadband versus baseband277
Broadband signaling277
Baseband signaling278 Transmission medium279
Twisted-pair280
Coaxial cable288
Fiber optic cable291 Access method292
Listeners and talkers292
Carrier-Sense Multiple Access with Collision Detection(CSMA/CD)293
Token passing294 3.3IEEE802Standards296
802committees297 Data link subdivision298
Medium Access Control299
Logical Link Control299 Physical layer subdivision300 3.4Ethernet Networks300
Original network components300
Coaxial cable300
Transceiver and transceiver cable301
Interface board302
Repeaters302 IEEE802.3networks303
Network names303
10BASE-5303
10BASE-2305
10BROAD-36306
1BASE-5307
10BASE-T308
100BASE-T311
100BASE-T4313
100BASE-TX315
100BASE-FX317
Network utilization317
Gigabit Ethernet319 Frame composition320
Preamble?eld321
Start of frame delimiter?eld321
Destination address?eld321
Source address?eld323
Type?eld324
Length?eld324
Data?eld324
Frame check sequence?eld324 Media Access Control(MAC)overview325 Logical Link Control(LLC)overview325 Types and classes of service326
Type1326
Type2327
Type3327
Classes of service328 3.5Token-Ring328
Redundant versus non-redundant main ring paths329 Cabling and device restrictions329
Intra-MAU cabling distances330
Adjusted ring length332
Other ring size considerations332 Transmission formats334 Token334 Abort334 Frame334
Starting/ending delimiters335
Access control337
Frame control338
Destination address339
Source address340
Routing information341
Information?eld342
Frame check sequence342
Frame status342 Medium Access Control343
MAC control343
Purge frame344
Beacon frame344
Duplicate address test frame345 Logical Link Control345
Review Questions346 4.Wide Area Network Transmission Equipment351
4.1Acoustic Couplers351
US and European compatibility352 Operation354 Problems in usage354 4.2Modems355
Basic components356
Modem transmitter section356
Scramblers358
Modulator,ampli?er and?lter358
Equalizer359
Bandwidth359
Delay distortion361 The modulation process363
Amplitude modulation363
Frequency modulation364
Phase modulation365 Bps versus baud366 Voice circuit parameters366 Combined modulation techniques367 Other modulation techniques369
Trellis coded modulation370
Convolutional encoder operation371 Echo cancellation372 Types of modems and features373
Mode of transmission373
Transmission technique373
Line use classi?cation374
Intelligence375
Method of fabrication375
Reverse and secondary channels376
Equalization377
Synchronization378
Multiport capability378
Security capability379
Multiple speed selection capability379
Voice/data capability380 Modem operations and compatibility380
300bps380
Echo suppression382
Disabling echo suppressors383
300to1800bps383
2400bps388
4800bps391
9600bps393
14400bps399
19200bps405
28800bps409
33600bps415
56kbps415 Non-standard modems418
Packetized ensemble protocol418
Asymmetrical modems419
Ping-pong modems421 Modem handshaking421 Modem testing and problem resolution422
Using modem indicators423
Modem testing427 4.3Intelligent Modems431
Command sets431
The Hayes command set432
Command use433
Result codes434
Extended AT commands435
Modem registers437
Compatibility438
Error detection and correction439
Flow control439 Methods of error detection and correction442
Rationale443
MNP444
LAP-M453
Compatibility issues453 Data compression454
Rationale454
MNP Class5compression454
MNP Class7enhanced data compression457
V.42bis459 Compatibility issues461 Throughput issues461 Negotiation problems462 Simultaneous voice and date operations463 Synchronous dialing language465 4.4Multiport Modems466
Operation466 Selection criteria467 Application example467 Standard and optional features470 4.5Multipoint Modems472
Factors affecting multipoint circuits473
Response time473
Transaction rate473
Delay factors473 Throughput problems475 Multipoint modem developments476 Remote multipoint testing477 4.6Security Modems477
Operation477 Memory capacity and device access478 Device limitations478 4.7Line Drivers479
Direct connection480 Using line drivers482 Applications483 4.8Limited-distance Modems484
Rationale and status485 Contrasting devices485 Transmission media485 Operational features487 Diagnostics488 4.9Broadband Modems489
Telephone and cable TV infrastructure489
Telephone490
Cable TV491 Cable modems494
LANcity LCP494
IEEE802.14proposal497
DSL modems499 4.10Digital Service Units505
Comparison of facilities505 Digital signaling506
Bipolar violations506 DDS structure507
Framing formats508
Signaling structure510
Timing511 Service units511
DSU/CSU tests and indicators513
DDS II514 Analog extensions to DDS514 Applications515 KiloStream service516
The KiloStream network517 4.11Channel Service Units518
Comparison to DSU/CSU520 North American framing520
D4framing520
Extended superframe format522 CEPT PCM-30format525
Frame composition525 T-carrier signal characteristics526
North America527
Europe529 4.12Parallel Interface Extenders529
Extender operation531 Extender components532 Application examples532
Review Question533 https://www.wendangku.net/doc/eb14074815.html,N Internetworking Devices539 5.1Bridges539
Basic operation540
Flooding541
Filtering and forwarding542 Types of bridges542
Transparent bridge543
Translating bridge543 Features544
Filtering and forwarding545
Selective forwarding545
Multiple port support546
Local and wide area interface support547
Transparent operation547
Frame translation547
Frame encapsulation547
Fabrication549 Routing methods549
Spanning tree protocol550
Source routing556
Source routing transparent bridges559
Network utilization560 5.2Routers562
Comparison to bridges563
Network layer operations564
Network address utilization564
Table operation565
Advantages of use565 IP support overview567
ARP569 Communications and routing protocols569
Routing protocols569
Handling non-routable protocols570
Communications protocols570
Protocol-dependent routers571
Protocol-independent routers572
Types of routing protocols575 5.3Gateways581
Overview581 Mainframe access582
Control unit connectivity582
Ethernet connectivity584
Alternative gateway methods585 5.4LAN Switches599
Conventional hub bottlenecks599
Ethernet hub operation600
Token-Ring hub operation601
Bottleneck creation601 Switching operations602
Basic components603
Key advantages of use604
Delay times604 Switching techniques605
Cross-point switching605
Store-and-forward606
Hybrid608
Port-based switching608
Segment-based switching609 Using LAN switches611
Network redistribution611
Server segmentation612
Backbone operation612
Handling speed incompatibilities614
ATM considerations615 5.5Access Servers618
Overview618 Utilization619 Review Questions620 6.Wide Area Network Data Concentration Equipment625
Equipment sizing625 6.1Multiplexers626
Evolution626 Comparison with other devices627 Device support627 Multiplexing techniques627
Frequency division multiplexing628
Time division multiplexing634 Multiplexing economics640 Statistical and intelligent multiplexers642
Statistical frame construction643
Flow control645
Service ratio646
Data source support647
Switching and port contention647
ITDMs648
STDM/ITDM statistics649
Features to consider650
Utilization considerations651
6.2T1/E1Multiplexers651
The T-carrier652
PCM652
Sampling652
Quantization653
Coding654
DS1framing654
Digital signal levels655
Framing changes656
T1signal characteristics657
European E1facilities657 The T1multiplexer658
Voice digitization techniques659
Waveform coding659
Vocoding661
Linear predictive coding661
Hybrid coding663
CELP coding663 T1multiplexer employment664 Features to consider665
Bandwidth utilization666
Bandwidth allocation667
Voice interface support669
Voice digitization support670
Internodal trunk support671
Subrate channel utilization671
Digital access cross-connect capability673
Gateway operation support673
Alternate routing and route generation674
Redundancy675
Maximum number of hops and nodes supported676
Diagnostics676
Con?guration rules676 6.3Subrate Voice/Data Multiplexers677
Operation677 Utilization678 6.4Inverse Multiplexers679
Operation679 Typical applications680 Contingency operations682 Economics of use683 Extended subchannel support683 Bandwidth-on-demand685 6.5Packet Assembler/Disassembler686
Applications687 Types of PADs687 X.3parameters688 6.6Frame Relay Access Device692
Hardware overview692 Comparison to routers693 The I-FRAD693 Protocol support694
SNA/SDLC encapsulation into TCP/IP694
SNA/SDLC conversion to SNA/LLC2694
Data Link Switching695
RFC1490695 Voice over Frame Relay696
Fragmentation696
Prioritization696
Buffering696
Voice digitization697 6.7Front-end Processors697
Communications controllers699
IBM3725700
IBM3745702
IBM3746705
6.8Modem-and Line-sharing Units706
A similar device707
Operation707
Device differences708
Sharing unit constraints709
Other sharing devices710 6.9Port-sharing Units711
When to consider711
Operation and usage713
Port-sharing as a supplement715
A similar device715
6.10Control Units716
Control unit concept716
Attachment methods717
Unit operation718
Protocol support719
Breaking the closed system720
Protocol converters720
Terminal interface unit721 6.11Port Selectors722
Types of devices722
Operation723
Computer site operations723
Usage decisions724
Port costs727
Load balancing728
Selector features728
Line-switching network729 6.12Protocol Converters730
Operation731
Physical/electrical conversion731
Data code/speed conversion731
Conversion categories731
Device operation conversion732
Device functionality conversion732
Character versus block mode operation733
Applications734 Review Questions735 7.Specialized Devices741 7.1Data Communications Switches741
Fallback switches742
Bypass switches743
Crossover switch744
Matrix switch744
Additional derivations746
Chaining switches747
Switch control748
Switching applications750 Hot-start con?guration751 Cold-start con?guration752
Sharing a backup router753
Router to router communications753
Adding a third EIA fallback switch754
Adding more switchable lines755
Chaining adds options755
Access to other lines756 7.2Data Compression Performing Devices757
Compression techniques757
Character oriented758
Null compression758
Run length compression758
Pattern substitution759
Statistical encoding759
Huffman coding760
LZW coding761 Bene?ts of compression763 Using compression performing devices764
Compression DSUs764
Multifunctional compression765 7.3Fiber Optic Transmission Systems766
System components767
The light source767
Optical cables768
Types of?bers769
Common cable types770
The light detector770 Other optical devices771
Optical modem771
Optical multiplexer772 Transmission advantages772
Bandwidth773
Electromagnetic non-susceptibility773
Signal attenuation774
Electrical hazard774
Security774
Weight and size774
Durability775 Limitations of use775
Cable splicing775
System cost775 Utilization economics776
Dedicated cable system777
Multichannel cable777
Optical multiplexers777 7.4Security Devices778
Password shortcomings779 Password combinations781 Illicit access782 Transmission security784
Manual techniques785
Automated techniques787 Modern developments789
DES algorithm789
Public versus private keys790
On-line applications791 LAN security794 Routers794
Access lists794
Con?guring an access list795
Extended access lists797
Additional extensions798
Router access799
Threats not handled799 Firewalls799
Placement800
Features801
Proxy services802
Using classes803
Address translation803
Stateful inspection804
Alerts805
Authentication806
Packet?ltering808 The gap to consider810
Review Questions811 Appendix A.Sizing Data Communications Network Devices813 A.1Device Sizing813
Sizing problem similarities814 Telephone terminology relationships815 The decision model817 Traf?c measurements818
Erlangs and call-seconds819
Grade of service820 Route dimensioning parameters820 Traf?c dimensioning formula821 A.2The Erlang Traf?c Formula821
Multiplexer sizing823 A.3The Poisson Formula826
Multiplexer sizing826 Formula comparison828 Economic constraints829 A.4Applying the Equipment Sizing Process829
Appendix B.Erlang Distribution Program833 Appendix C.Poisson Distribution Program835 Appendix D.Multidrop Line Routing Analysis837 The minimum-spanning-tree technique837 The minimum-spanning-tree algorithm839 Minimum-spanning-tree problems840
Terminal response times840
Probability of transmission errors841
Front-end processor limitations842
Large network design842
Appendix E.CSMA/CD Network Performance843 Determining the network frame rate843 Index847
PREFACE
Over?fteen years ago I introduced the?rst edition of this book with the statement `data communications networking devices are the building blocks upon which networks are constructed.'Although networking technology has made signi?cant advances,that statement retains its validity.Today you can use devices such as bridges and routers that were non-existent in the late1970s to link local and wide area networks together,while boosting LAN productivity and access through the use of switches and remote access servers that represent products of the1990s. Thus,the basic rationale and goal of this fourth edition,which is to provide readers with an intimate awareness of the operation and utilization of important networking products that can be used in the design,modi?cation,or optimization of a data communications network,has not changed from the rationale and goal of the?rst edition.What has changed is the scope and depth of the material included in this book.
In developing this new edition I have taken into consideration and acted upon comments received from both individuals and professors who used the book for a college course on networking.Major changes include an expansion and subdivision of the Fundamental Concepts chapter,which now covers both WANs and LANs in a series of separate chapters focused upon fundamental concepts and advanced networking topics.Other signi?cant changes in this new edition include a chapter covering Wide Area Networks as a separate entity and another covering LAN internetworking devices.In addition,a signi?cant amount of material was revised and updated to provide detailed information covering the operation and utilization of additional networking devices and the updating of information concerning the operating characteristics of other devices.To facilitate the use of this book as a text as well as for reader review purposes,the questions at the end of each chapter reference the sections in each chapter.Through the use of a numbering scheme,students can easily reference an appropriate section in the book for assistance in answering a question while instructors can easily reference the assignment of questions to reading assignments based upon speci?c sections within chapters.
The expansion of the Fundamental Concepts chapter followed by the addition of two new chapters covering wide area networks and local area networks provides readers new to the?eld of data communications with the ability to use these chapters as a detailed introduction to this?eld.For more experienced readers the information in these chapters can be used as a reference to the many facets of data communications.