Juniper and Cisco routing

Walter J. Goralski

Juniper® and

Cisco Routing

Policy and Protocols for

Multivendor IP Networks

TEAMFLY

Team-Fly®

Juniper® and Cisco Routing

Policy and Protocols for

Multivendor IP Networks

Walter J. Goralski

Juniper® and

Cisco Routing

Policy and Protocols for

Multivendor IP Networks

Publisher: Robert Ipsen

Editor: Carol Long

Developmental Editor: Scott Amerman

Associate Managing Editor: John Atkins

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Copyright © 2002 by Walter J. Goralski. All rights reserved.

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Library of Congress Cataloging-in-Publication Data:

ISBN: 0-471-21592-9

Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

Acknowledgments xv

Introduction xvii

Part 1 The Internet and the Router 1

Chapter 1 A Brief History of the Internet and Router 3

The Pre-Web Internet 6

The Web Comes to Town 13

The Birth of the Web 15

The Web Explodes 19

The Birth of the ISPs 22

The Router’s Role 26

Chapter 2 TCP/IP Survivor’s Guide 33

Internet Protocol Suite: An Overview 34

TCP/IP Layers and the Client/Server Model 35

The Network Layer 38

The IP Layer 40

The Transport Layer 43

The Application Layer 47

Putting It All Together 50

Key TCP/IP Applications 51

FTP (File Transfer Protocol) 51

Telnet (Remote Login) 53

DNS (Domain Name Service) 54

SMTP (Simple Mail Transfer Protocol)

and Post Office Protocol (POP) 56

Trivial File Transfer Protocol (TFTP)

and Boot Protocol (BOOTP) 58

Contents

v

Network File System (NFS) 60

Simple Network Management Protocol 62

X Windows 64

Multimedia and Multicast 65

MIME (Multipurpose Internet Mail Extensions) 66

Multicast and the Multicast Backbone 69

ARP and ICMP 70

ARP Protocols 71

Internet Control Message Protocol (ICMP) 73

Chapter 3 IP Addressing and Routing 77

The IP Address 77

Private and Martian IP Addresses 82

Reading IP Addresses 83

Direct and Indirect Routing 83

Direct Delivery or No Routing Required 84

The IP Router and Indirect Delivery 87

Maximum Transmission Unit (MTU) 92

Fragmentation and Reassembly 95

Limitations of IPv4 98

Features of IPv6 100

The IPv6 Header Structure 103

IPv6 Header Changes 104

IPv6 Addresses 106

The IPv6 Address Prefix 107

IPv4 Packet Processing 109

IPv6 Packet Processing 110

The IPv4/IPv6 Transition: Terminology 110

IPv4/IPv6 Device Compatibility 111

Deploying IPv6 112

Chapter 4 Subnets and Supernets 115

IP Addressing and the Internet 116

IP Subnetting 121

Where IP Addresses Come From 122

The Basics of Subnetting 123

More Advanced Subnetting 127

Classless Interdomain Routing (CIDR) 130

VLSM and the Longest-Match Rule 135

The Longest-Match Rule 137

Radix Tree Representation 138

Aggregation 140

Aggregates on the Internet 142

Aggregates and Routing Policy 148

IPv6 Prefixes 150

Summary: The Five Roles for Routing Policy 152

vi Contents

Chapter 5 Cisco Router Configuration 155

Cisco Router Architecture 157

Cisco Hardware 158

Cisco Memory 159

RAM/DRAM 160

NVRAM 160

Flash Memory 160

ROM 161

Cisco Router Access 161

Cisco’s Router Operating System 163

Cisco Router Products 164

SOHO Routers 165

Midrange Routers 166

Backbone Routers 166

Cisco’s Hierarchical Vision 168

Configuring Cisco Routers 171

Getting Started 172

Operating Modes 172

Configuration Files 173

Cisco Configuration Example 178

Initial Setup 179

Loopback, Static Routes, and an Aggregate Route 184

Setting the Loopback IP Address 184

Adding Static Route Addresses 185

Setting the Aggregate 188

Viewing the Results 191

More Cisco Configuration Tools 193

Chapter 6 Juniper Networks Router Configuration 195

Router Architecture: Juniper Networks 196

Juniper Networks Hardware: An Overview 197

The Routing Engine (RE) 200

Packet Forwarding Engine (PFE) 200

Physical Interface Card (PIC) 201

Flexible PIC Concentrator (FPC) 201

The Router Midplane 202

The Control Board 202

Packet Flow 203

Juniper Networks Router Access 205

Juniper Network’s Router Operating System 206

Juniper Networks Router Products 209

M40 210

M20 211

M160 211

M5/M10 213

Contents vii

Configuring Juniper Networks Routers 214

Getting Started 214

“Operating” Modes 215

Configuration Files 218

Juniper Networks Configuration Example 219

Initial Setup 221

Loopback, Static Routes, and Aggregate Routes 226

Setting the Loopback IP address 226

Adding Static Route Addresses 227

Setting the Aggregate 228

Viewing the Results 232

More Juniper Networks Configuration Tools 235

Part 2 Interior Routing Protocols 237

Chapter 7 Routing Information Protocol (RIP) 239

Distance-Vector Routing 240

Simple Hop-Count Routing 242

Broken Links 245

Distance-Vector Consequences 250

Split Horizon 251

Triggered Updates 252

RIPv1 253

RIPv1 Limitations 259

RIPv2 260

Authentication 262

Subnet Masks 264

Next-Hop Identification 264

Multicasting 266

RIPng for IPv6 266

Interior Gateway Routing Protocol (IGRP) and

Enhanced IGRP (EIGRP) 270

IGRP 270

EIGRP 272

Chapter 8 Configuring RIP 273

Fast Ethernet for Multivendor Connectivity 275

RIP and Static Routes 275

Cisco RIP Configuration 276

Cisco Fast Ethernet 276

Cisco Access Router RIPv1 Configuration 277

Viewing the Results for RIPv1 280

A Routing Policy to Redistribute Static Routes 282

Juniper Networks RIP Configuration 284

Juniper Access Router RIPv2 Configuration 284

Viewing the RIPv2 Results 287

The Send-Statics Routing Policy 289

A Note on RIPv1 Juniper Network Router Operation 291

viii Contents

Chapter 9 Open Shortest Path First (OSPF) 293

Link States and Shortest Paths 295

What OSPF Can Do 297

The Theory of OSPF 299

OSPF Network Types 303

OSPF Areas and Router Types 305

OSPF Area Types 305

Designated Router (DR) and Backup Designated Router (BDR) 308

OSPF Packets 309

The Hello Packet 310

The Database Description Packet 312

The Link-State Request Packet 313

The Link-State Update Packet 314

The Link-State Acknowledgment Packet 315

Database Synchronization and Neighbor States 316

OSPF LSA Types 318

The Router LSA 319

The Network LSA 322

The Network Summary and ASBR Summary LSAs 323

The AS External LSA 324

The NSSA External LSA 325

OSPF for IPv6 325

OSPF in the Real World 327

Chapter 10 Configuring OSPF 331

Basic OSPF Backbone Configuration 335

Viewing the Routing Table 336

ASBR0 Cisco Configuration 338

Nonbackbone, Nonstub Area Configuration 341

Viewing the Routing Table and Link-State Database 342

ABR1 Cisco Configuration 348

Stub Area Configuration 351

Viewing the Routing Table and Link-State Database 353

ABR2 Stub Cisco Configuration 357

Total Stub Area Configuration 360

Viewing the Routing Table and Link-State Database 362

ABR3 Total Stub Cisco Configuration 365

NSSA Configuration 367

Viewing the Routing Table and Link-State Database 370

ASBR4 NSSA Cisco Configuration 373

Chapter 11 Intermediate System–Intermediate System (IS-IS) 377

The Attraction of IS-IS 378

My Protocol’s Better Than Yours 379

IS-IS and OSPF 380

Similarities between IS-IS and OSPF 381

Contents ix

TEAMFLY

Team-Fly®

Differences between IS-IS and OSPF 381

Areas 382

Route Leaking 383

Network Addresses 385

Network Types 387

Designated Intermediate System (DIS) 387

LSP Handling 388

Metrics 389

IS-IS PDUs 389

Type/Length/Value (TLV) 391

IS-IS Hello PDU 394

IS-IS for IPv6 402

Chapter 12 Configuring IS-IS 405

Basic IS-IS Area 0001 Configuration 409

Viewing the Routing Table 413

L2-Only Cisco Configuration 415

IS-IS Area 0002 Configuration 418

L1/L2_2to1 Configuration 418

L1_only2A Configuration 420

L1_only2B Configuration 421

Viewing the Routing Table and Link-State Database 423

L1_only2A Routing Table and Link-State Database 423

L2_only2B Routing Table and Link-State Database 425

L1/L2_2to1 Routing Table and Link-State Database 427

L1/L2_2to1 Cisco Configuration 431

IS-IS Area 0003 Configuration 435

L1/L2_3to1 Configuration 435

L1_only3A and L1_only3B Configuration 436

Viewing the Routing Table and Link-State Database 437

L1/L2_3to1 Routing Table and Link-State Database 439

L1_only3A and L1_only3B Routing Table and

Link-State Database 441

L1_only3B Cisco Configuration 443

Linking L1_only2B and L1_only3A 445

Part 3 Exterior Routing Protocols 449

Chapter 13 Border Gateway Protocol (BGP) 451

BGP Is Born 453

BGP as a Path Vector Protocol 454

IBPG and EBGP 455

BGP “Next Hops” and IGP Next Hops 457

IBGP and the IGP 458

Other Types of BGP 462

BGP Attributes 463

The ORIGIN Attribute 465

The AS_PATH Attribute 465

x Contents

The NEXT_HOP Attribute 465

The LOCAL_PREF Attribute 466

The MULTI_EXIT_DISC (MED) Attribute 466

The ATOMIC_AGGREGATE and AGGREGATOR Attributes 467

The COMMUNITY Attribute 468

The ORIGINATOR_ID and CLUSTER_LIST Attributes 469

BGP Route Selection 470

BGP as a Policy-Driven Routing Protocol 472

BGP Scaling 473

Route Reflectors 474

Confederations 476

Route Damping 477

BGP Message Types 479

BGP Message Formats 480

The Open Message 480

The Update Message 481

The Notification Message 484

Chapter 14 Configuring BGP 487

Basic BGP Configuration 492

Viewing the Routing Table 494

Earth Cisco Configuration 496

IBGP Mesh Configuration 498

Solving the BGP Next Hop Issue 506

Next Hop Self on Juniper Networks Router 507

Cisco IBGP Configuration 509

Adding the AS 64777 Router 512

BGP Route Reflectors 515

BGP Route Reflectors on Juniper Networks 515

A Cisco Route Reflector 520

BGP Confederations 522

A Cisco Confederation Router 525

Summary 527

Part 4 IGP Routing Policies 529

Chapter 15 Routing Policy 531

Cisco Routing Policy 534

Redistribution 536

Route Maps 538

Distribution Lists 540

Prefix Lists 541

Access Lists 542

A Few Routing Policy Examples 543

Juniper Networks Routing Policy 545

Structure of a Juniper Networks Routing Policy 549

Match Conditions 551

Actions 553

Contents xi

Route Filter Match Types 556

Routing Policy Notes 560

Some Routing Policy Examples 561

Regular Expressions and Routing Policy 563

Chapter 16 IGP Routing Policies 565

OSPF Routing Policies 566

Setting Metrics on Redistributed Routes 566

Type 1 and Type 2 External Routes 568

Cisco OSPF External Types 571

Juniper Networks OSPF External Types 571

OSPF Area Range 572

Cisco Area Range 573

Juniper Networks Area Range 574

Changing OSPF Administrative Distance/Protocol Preference 575

Gracefully Cutover OSPF to IS-IS 576

Cisco OSPF to IS-IS Cutover 578

Juniper Networks OSPF to IS-IS Cutover 579

IS-IS Routing Policies 579

Juniper Networks Router IS-IS Metrics 580

IS-IS Route Leaking 581

Route Leaking Mechanisms 585

Route Leaking, TLVs, and Metrics 588

Configuring Route Leaking 590

Cisco Route Leaking 590

Juniper Networks Route Leaking 593

IS-IS Area Range (Summary Address) 594

Part 5 EGP Routing Policies 597

Chapter 17 Basic BGP Routing Policies 599

Aggregation 600

Cisco Aggregation 602

Juniper Networks Aggregation 604

The Origin and MED Attributes 608

The Origin Attribute 609

Using the Origin Attribute 611

Routing Policies for the Origin Attribute 614

Cisco to Juniper Networks 615

Juniper Networks to Cisco 616

The Policy for AS 65001 617

The MED Attribute 618

Cisco MED Routing Policy 622

Juniper Networks MED Routing Policy 623

MEDs and Aggregates 624

xii Contents

Chapter 18 AS Path and Local Preference 627

The AS Path Attribute 629

Removing Private AS Numbers 631

Routing Policy for the AS Path 634

The Cisco AS Path Routing Policy 634

The Juniper Networks AS Path Routing Policy 635

AS Path Regular Expressions 635

The Null AS Path 637

Cisco AS Path Regular Expressions 638

Juniper Networks AS Path Regular Expressions 642

The Local Preference Attribute 647

Cisco Routers and Local Preference 653

Juniper Networks Routers and Local Preference 654

Chapter 19 BGP Community and Route Damping 657

The BGP Community Attribute 658

Well-Known Communities 659

Using Communities to Represent Local Preference 664

Communities and Transit Traffic 665

Communities on a Cisco Router 666

Cisco Community Regular Expressions 669

Communities on a Juniper Networks Router 670

Juniper Networks Community Regular Expressions 673

Route Damping 676

How Route Damping Works 679

Cisco Route Damping 682

Juniper Networks Route Damping 685

Acronyms 689

Bibliography 697

Index 701

Contents xiii