Internetworking Technologies Handbook,

Second Edition

Kevin Downes Merilee Ford H. Kim Lew Steve Spanier Tim Stevenson

M CISCOSYSTEMS T f y p

M A C M I L L A N T E C H N I C A L P U B L I S H I N G

C i s c o P R E S S U-S-A

Macmillan Technical Publishing 201 West 103 r d Street Indianapolis, IN 46290 USA

Table of Contents

PART 1 INTRODUCTION TO INTERNETWORKING

Chapter 1 Internetworking Basics 3 What is an Internetwork? 3 Open Systems Interconnection (OSI) Reference

Model 6 Information Formats 19 ISO Hierarchy of Networks 21 Connection-Oriented and Connectionless Network

Services 22 Internetwork Addressing 24 Flow-Control Basics 31 Error-Checking Basics 32 Multiplexing Basics 33 Standards Organizations 35

Chapter 2 Introduction to LAN Protocols 37 Introduction to LAN Protocols What Is a LAN? 38

LAN Protocols and the OSI Reference Model LAN Media-Access Methods 39

39

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viii Internetworking Technologies Handbook, Second Edition

LAN Transmission Methods LAN Topologies 41 LAN Devices 43

40

Chapter 3 Introduction to WAN Technologies 45 What Is a WAN? 45 Point-to-Point Links 46 Circuit Switching 47 Packet Switching 48 WAN Virtual Circuits 49 WAN Dialup Services 50 WAN Devices 51

Chapter 4 Bridging and Switching Basics 55 What Are Bridges and Switches? 55 Link-Layer Device Overview 56 Types of Bridges 58 Types of Switches 60

Chapter 5 Routing Basics 63 What Is Routing? 63 Routing Components 64 Routing Algorithms 68 Network Protocols 75

Chapter 6 Network Management Basics 77 What is Network Management? 77 Network Management Architecture 78 ISO Network Management Model 79

PART 2 LAN PROTOCOLS

Chapter 7 Ethernet Technologies 87 Background 87 Ethernet and IEEE 802.3 88

Table of Contents ix

100-Mbps Ethernet 94 lOOVG-AnyLAN 103 Gigabit Ethernet 107 Gigabit Ethernet Protocol Architecture 107 Migration to Gigabit Ethernet 120 Gigabit Ethernet Campus Applications 123

Chapter 8 Fiber Distributed Data Interface (FDDI) 125 Background 125 FDDI Transmission Media 127 FDDI Specifications 128 FDDI Station-Attachment Types 130 FDDI Fault Tolerance 131 FDDI Frame Format 136 Copper Distributed Data Interface (CDDI) 137

Chapter 9 Token Ring/IEEE 802.5 139 Background 139 Physical Connections 140 Token Ring Operation 141 Priority System 142 Fault-Management Mechanisms 143 Frame Format 144

PART 3 WAN TECHNOLOGIES

Chapter 10 Frame Relay 149 Background 149 Frame Relay Devices 151 Frame Relay Virtual Circuits 152 Congestion-Control Mechanisms 155 Frame Relay Local Management Interface (LMI) 156 Frame Relay Network Implementation 157 Frame Relay Frame Formats 159

X Internetworking Technologies Handbook, Second Edition

Chapter 11 High-Speed Serial Interface 165 Background 165 HSSI Interface Basics 166 HSSI Operation 167

Chapter 12 Integrated Services Digital Network (ISDN) 169 Background 169 ISDN Components 169 Services 172 Layer 1 172 Layer 2 174 Layer 3 175

Chapter 13 Point-to-Point Protocol 177 Background 177 PPP Components 177 General Operation 178 Physical-Layer Requirements 178 PPP Link Layer 179

Chapter 14 Switched Multimegabit Data Service (SMDS) 183 Background 183 SMDS Network Components 183 SMDS Interface Protocol (SIP) 185 Distributed Queue Dual Bus (DQDB) 187 SMDS Access Classes 189 SMDS Addressing Overview 189 SMDS Reference: SIP Level 3 PDU Format 190 SMDS Reference: SIP Level 2 Cell Format 192

Chapter 15 Digital Subscriber Line 195 Asymmetric Digital Subscriber Line (ADSL)

Very-High-Data-Rate Digital Subscriber Line

(VDSL) 202

196

Table of Contents xi

Chapter 16 Synchronous Data Link Control and Derivatives 215 Background 215

SDLC Types and Topologies 216

SDLC Frame Format 217

Derivative Protocols 220

Chapter 17 X.25 223

Background 223 X.25 Devices and Protocol Operation 223

The X.25 Protocol Suite 227 LAPB Frame Format 231 X.121 Address Format 233

Chapter 18 Multiservice Access Technologies 235

The Importance of Voice over IP 235 Packet Voice 236 Packet Voice Transport 237

Voice over ATM 238 Voice over Frame Relay 244

Voice over IP 245 Applying Packet Voice 249

Chapter 19 Virtual Private Networks (VPNs) 253 Cisco Systems VPNs 254

PART 4 BRIDGING AND SWITCHING

Chapter 20 Asynchronous Transfer Mode (ATM) Switching 269

Background 269

ATM Devices and the Network Environment 270 ATM Cell-Header Format 274

xii Internetworking Technologies Handbook, Second Edition

ATM Services 276 ATM Switching Operations 277 ATM Reference Model 277 ATM Addressing 283 ATM Connections 286 ATM and Multicasting 287 ATM Quality of Service (QoS) 288 ATM Signaling and Connection Establishment 289 ATM Connection-Management Messages 290 LAN Emulation (LANE) 291

Chapter 21 Data-Link Switching 301 Background 301 DLSw Contrasted with Source-Route Bridging 303 DLSw SNA Support 305 DLSw Switch-to-Switch Protocol (SSP) 306 DLSw Operation 307 DLSw Message Formats 311

Chapter 22 LAN Switching 317 Background 317 LAN Switch Operation 319 LAN Switch and the OSI Model 321

Chapter 23 Tag Switching 323 Background 323 Tag-Switching Architecture 324 Destination-Based Routing 326 Hierarchical Routing 329 Flexible Routing using Explicit Routes 330 Multicast Routing 331 Tag Switching with ATM 332 Quality of Service 333 IP Switching 334

Chapter 24

Chapter 25

Mixed-Media Bridging 335 Background 335 Translation Challenges 336 Translational Bridging 338 Source-Route Transparent Bridging 341

Source-Route Bridging (SRB)

Background 343 SRB Algorithm 343 Frame Format 345

343

Chapter 26 Transparent Bridging 349

Background 349 Transparent Bridging Operation Frame Format 355

349

PART 5 NETWORK PROTOCOLS

Chapter 27 AppleTalk 361

Background 361 AppleTalk Network Components 362

AppleTalk Physical and Data Link Layers 367 Network Addresses 373 AppleTalk Address-Resolution Protocol (AARP) 375

Datagram-Delivery Protocol (DDP) Overview 377

AppleTalk Transport Layer 378 AppleTalk Upper-Layer Protocols 385

AppleTalk Protocol Suite 388

Chapter 28 DECnet 393

Background 393

DECnet Phase IV Digital Network Architecture (DNA) 394

xiv Internetworking Technologies Handbook, Second Edition

DECnet/OSI Digital Network Architecture (DNA) 397 DECnet Media Access 399 DECnet Routing 399 DECnet End-Communications Layer 401 DECnet/OSI Transport Layer 401 DECnet Phase IV Upper Layers 402 DECnet/OSI Upper Layers 404

Chapter 29 IBM Systems Network Architecture (SNA) Protocols 407 Background 407 Traditional SNA Environments 408 IBM Peer-Based Networking 415 Basic Information Unit (BIU) Format 422 Path Information Unit (PIU) Format 424

Chapter 30 Internet Protocols 429 Background 429 Internet Protocol (IP) 431 Address Resolution Protocol (ARP) Overview 441 Internet Routing 442 Internet Control Message Protocol (ICMP) 443 Transmission Control Protocol (TCP) 445 User Datagram Protocol (UDP) 450 Internet Protocols Application-Layer Protocols 451

Chapter 31 NetWare Protocols 453 Background 453

NetWare Media Access 455 Internetwork Packet Exchange (IPX) Overview 455 IPX Encapsulation Types 456 Service Advertisement Protocol (SAP) 458 NetWare Transport Layer 459

Table of Contents xv

NetWare Upper-Layer Protocols and Services 459 IPX Packet Format 460

Chapter 32 Open System Interconnection (OSI) Protocols 463

Background 463 OSI Networking Protocols 464

Chapter 33 Banyan VINES 477

Background 477 Media Access 478 Network Layer 478 Transport Layer 486 Upper-Layer Protocols 487

Chapter 34 Xerox Network Systems (XNS) 489

Background 489 XNS Hierarchy Overview 490 Media Access 491 Network Layer 491 Transport Layer 494 Upper-Layer Protocols 495

PART 6 ROUTING PROTOCOLS

Chapter 35 Border Gateway Protocol (BGP) 499

Background 499 BGP Operation 501 BGP Routing 502 BGP Message Types 503 BGP Packet Formats 504

Chapter 36 Enhanced IGRP 511

Background 511

Enhanced IGRP Capabilities and Attributes 512

xvi Internetworking Technologies Handbook, Second Edition

Underlying Processes and Technologies 513 Routing Concepts 514 Enhanced IGRP Packet Types 517

Chapter 37 IBM Systems Network Architecture (SNA) Routing 519 Background 519 IBM SNA Session Connectors 520 IBM SNA Transmission Groups (TGs) 521 IBM SNA Explicit and Virtual Routes 521 IBM SNA Class of Service (COS) 522 IBM SNA Subarea Routing 525 IBM Advanced Peer-to-Peer Networking (APPN)

Routing 527

Chapter 38 Interior Gateway Routing Protocol 533 Background 533 IGRP Protocol Characteristics 534

Chapter 39 Internet Protocol (IP) Multicast 539 Background 539 Internet Group-Membership Protocol (IGMP) 540 IP Multicast Routing Protocols 541

Chapter 40 NetWare Link-Services Protocol (NLSP) 545 Background 545 NLSP Hierarchical Routing 546 NLSP Operation 549 NLSP Hierarchical Addressing 550 NLSP Hello Packets 552

Chapter 41 Open Systems Interconnection (OSI) Routing Protocol 557 Background 557 End System-to-intermediate System (ES-IS) 559

Table of Contents xvii

Intermediate System-to-Intermediate System (IS-IS) 560

Integrated IS-IS 564 Interdomain Routing Protocol (IDRP) 564

Chapter 42 Open Shortest Path First (OSPF) 567 Background 567 Routing Hierarchy 568 SPF Algorithm 571 Packet Format 572 Additional OSPF Features 573

Chapter 43 Resource-Reservation Protocol (RSVP) 575 Background 575 RSVP Data Flows 576 RSVP Quality of Service (QoS) 578 RSVP Session Start-up 579 RSVP Reservation Style 579 RSVP Soft State Implementation 581 RSVP Operational Model 582 RSVP Messages 585 RSVP Packet Format 587

Chapter 44 Routing Information Protocol (RIP) 593 Background 593 Routing Updates 594 RIP Routing Metric 594 RIP Stability Features 595 RIP Timers 595 Packet Formats 595

Chapter 45 Simple Multicast Routing Protocol (SMRP) 601 Background 601 SMRP Multicast Transport Services 604

xviii Internetworking Technologies Handbook, Second Edition

SMRP Transaction Example 612

SMRP Packet Format 612

Chapter 46 Quality of Service (QoS) Networking 615 Network QoS Defined 615 Basic QoS Architecture 617 QoS Signaling 633 RSVP: Guaranteeing QoS 636 Cisco's QoS Policy, Management, and Accounting

Capabilities 637

PART 7 INTERNET ACCESS TECHNOLOGIES

Chapter 47 Security Technologies 647

Security Issues When Connecting to the Internet 647 Trusted, Untrusted, and Unknown Networks 657 Establishing a Security Perimeter 658

Chapter 48 Directory-Enabled Networking 665 The Purpose and Scope of Directory-Enabled

Networking 667

The Extended Schema and Other Device Schemata 672

Chapter 49 Network Caching Technologies 675 Growth of Web Content 675 Caching 676 Cisco's Network-Based Shared Caching 680

PART 8 NETWORK MANAGEMENT

Chapter 50 IBM Network Management 689

Background 689 IBM Network-Management Functional Areas 690

IBM Network-Management Architectures 693 IBM Network-Management Platforms 695

Chapter 51 Remote Monitoring (RMON) 697 Background 697 RMON Groups 698

Chapter 52 Simple Network Management Protocol (SNMP) 701 Background 701 SNMP Basic Components 702 SNMP Basic Commands 703 SNMP Management Information Base (MIB) 704 SNMP and Data Representation 706 SNMP Version 1 (SNMPvl) 706 SNMP Version 2 (SNMPv2) 708 SNMP Management 710 SNMP Security 710 SNMP Interoperability 711 SNMP Reference: SNMPvl Message Formats 712 SNMP Reference: SNMPv2 Message Format 714

Internetworking Terms and Acronyms 719

Index 805