Implementing Cisco IP Routing (ROUTE) Foundation Learning Guide

Diane Teare, P.Eng, CCNP, CCDP, CCSI, PMP, is a professional in the networking, training, project management, and e-learning fields. She has more than 25 years of experience in designing, implementing, and troubleshooting network hardware and software, and has been involved in teaching, course design, and project management. She has extensive knowledge of network design and routing technologies. Diane is a Cisco Certified Systems Instructor (CCSI), and holds her Cisco Certified Network Professional (CCNP), Cisco Certified Design Professional (CCDP), and Project Management Professional (PMP) certifications. She is an instructor, and the Course Director for the CCNA and CCNP Routing and Switching curriculum, with one of the largest authorized Cisco Learning Partners. She was the director of e-learning for the same company, where she was responsible for planning and supporting all the company’s e-learning offerings in Canada, including Cisco courses. Diane has a bachelor’s degree in applied science in electrical engineering and a master’s degree in applied science in management science. She authored or co-authored the following Cisco Press titles: the first edition of this book; the second edition of Designing Cisco Network Service Architectures (ARCH); Campus Network Design Fundamentals; the three editions of Authorized Self-Study Guide Building Scalable Cisco Internetworks (BSCI); and Building Scalable Cisco Networks. Diane edited the first two editions of the Authorized Self-Study Guide Designing for Cisco Internetwork Solutions (DESGN), and Designing Cisco Networks. Bob Vachon, is a professor at Cambrian College in Sudbury, Ontario, Canada, where he teaches Cisco networking infrastructure courses. He has more than 30 years of work and teaching experience in the computer networking and information technology field. Since 2001, Bob has collaborated as team lead, lead author, and subject matter expert on various CCNA, CCNA-S, and CCNP projects for Cisco and the Cisco Networking Academy. He also was a contributing author for the Routing Protocols Companion Guide, Connecting Networks Companion Guide, and authored the CCNA Security (640-554) Portable Command Guide. In his downtime, Bob enjoys playing the guitar, playing pool, and either working in his gardens or white-water canoe tripping. Rick Graziani teaches computer science and computer networking courses at Cabrillo College in Aptos, California. Rick has worked and taught in the computer networking and information technology field for almost 30 years. Before teaching, Rick worked in IT for various companies, including Santa Cruz Operation, Tandem Computers, and Lockheed Missiles and Space Corporation. He holds a Master of Arts degree in computer science and systems theory from California State University Monterey Bay. Rick also works for the Cisco Networking Academy Curriculum Engineering team and has written other books for Cisco Press, including IPv6 Fundamentals. When Rick is not working, he is most likely surfing. Rick is an avid surfer who enjoys surfing at his favorite Santa Cruz breaks.

Introduction xxv

Chapter 1 Basic Network and Routing Concepts 1

Differentiating Routing Protocols 2

Enterprise Network Infrastructure 2

Role of Dynamic Routing Protocols 3

Choosing a of Dynamic Routing Protocols 5

IGP versus EGP 5

Types of Routing Protocols 7

Convergence 8

Route Summarization 9

Route Protocol Scalability 10

Understanding Network Technologies 10

Traffic Types 11

IPv6 Address Types 13

ICMPv6 Neighbor Discovery 14

Network Types 15

NBMA Networks 16

Routing Over the Internet 18

Connecting Remote Locations with Headquarters 18

Principles of Static Routing 19

Configuring an IPv4 Static Route 20

Configuring a Static Default Route 22

Basic PPP Overview 23

PPP Authentication Overview 23

PPPoE 26

Basic Frame Relay Overview 28

VPN Connectivity Overview 31

MPLS-based VPNs 31

Tunneling VPNs 32

Hybrid VPNs 32

Routing Across MPLS VPNs 32

Routing Over GRE Tunnel 34

Dynamic Multipoint Virtual Private Network 35

Multipoint GRE 36

NHRP 37

IPsec 39

Routing and TCP/IP Operations 40

MSS, Fragmentation, and PMTUD 40

IPv4 Fragmentation and PMTUD 41

Bandwidth Delay Product 41

TCP Starvation 42

Latency 42

ICMP Redirect 42

Implementing RIPng 43

RIP Overview 43

RIPv2 Overview 45

Configuring RIPng 47

Basic RIPng Configuration 47

Propagating a Default Route 50

Investigating the RIPng Database 53

Summary 55

Review Questions 56

Chapter 2 EIGRP Implementation 59

Establishing EIGRP Neighbor Relationships 60

EIGRP Features 60

EIGRP Features 62

EIGRP Operation Overview 63

Configuring and Verifying Basic EIGRP for IPv4 64

Manipulating EIGRP Timers 73

EIGRP Neighbor Relationship over Frame Relay 74

Establishing EIGRP over Layer 3 MPLS VPN 74

Establishing EIGRP over Layer 2 MPLS VPN 75

Building the EIGRP Topology Table 76

Building and Examining the EIGRP Topology Table 77

Choosing the Best Path 80

Exchange of Routing Knowledge in EIGRP 88

EIGRP Metric 88

EIGRP Metric Calculation 89

EIGRP Wide Metrics 90

EIGRP Metric Calculation Example 90

EIGRP Metric Calculation Example 91

EIGRP Path Calculation Example 92

Optimizing EIGRP Behavior 94

EIGRP Queries 95

EIGRP Stub Routers 96

Configuring EIGRP Stub Routing 97

EIGRP Stub Options 100

Stuck in Active 108

Reducing Query Scope by Using Summary Routes 109

Configuring EIGRP Summarization 110

Determining the Summary Route 116

Obtaining Default Route 120

Load Balancing with EIGRP 123

Configuring EIGRP Load Balancing 123

EIGRP Load Balancing 124

EIGRP Load Balancing Across Unequal-Metric Paths 126

Configuring EIGRP for IPv6 128

Overview of EIGRP for IPv6 128

Configuring and Verifying EIGRP for IPv6 129

EIGRP for IPv6 Configuration 130

Determining the IPv6 Summary Route 134

Named EIGRP Configuration 136

Introduction to Named EIGRP Configuration 136

Configuring Named EIGRP 137

Address Families 139

EIGRP for IPv4 Address Family 139

EIGRP for IPv6 Address Family 142

Named EIGRP Configuration Modes 148

Classic Versus Named EIGRP Configuration 150

Summary 151

Review Questions 152

Chapter 3 OSPF Implementation 155

Establishing OSPF Neighbor Relationships 155

OSPF Features 156

OSPF Operation Overview 157

Hierarchical Structure of OSPF 158

Design Restrictions of OSPF 160

OSPF Message Types 160

Basic OSPF Configuration 161

Optimizing OSPF Adjacency Behavior 170

Using OSPF Priority in the DR/BDR Election 174

OSPF Behavior in NBMA Hub-and-Spoke Topology 175

The Importance of MTU 177

Manipulating OSPF Timers 179

OSPF Neighbor Relationship over Point-to-Point Links 182

OSPF Neighbor Relationship over Layer 3 MPLS VPN 182

OSPF Neighbor Relationship over Layer 2 MPLS VPN 184

OSPF Neighbor States 184

OSPF Network Types 186

Configuring Passive Interfaces 187

Building the Link-State Database 187

OSPF LSA Types 188

Examining the OSPF Link-State Database 189

OSPF Link-State Database 190

OSPF Type 2 Network LSA 196

OSPF Type 3 Summary LSA 197

OSPF Type 4 ASBR Summary LSA 199

OSPF Type 5 External LSA 201

Periodic OSPF Database Changes 203

Exchanging and Synchronizing LSDBs 204

Synchronizing the LSDB on Multiaccess Networks 206

Running the SPF Algorithm 207

Configuring OSPF Path Selection 208

OSPF Path Selection 208

OSPF Best Path Calculation 210

Default OSPF Costs 211

Calculating the Cost of Intra-Area Routes 214

Calculating the Cost of Interarea Routes 214

Selecting Between Intra-Area and Interarea Routes 215

Optimizing OSPF Behavior 215

OSPF Route Summarization 216

Benefits of Route Summarization 217

Configuring OSPF Route Summarization 218

Summarization on ABRs 223

Summarization on ASBRs 224

OSPF Virtual Links 225

Configuring OSPF Virtual Links 227

Configuring OSPF Stub Areas 229

OSPF Stub Areas 230

OSPF Totally Stubby Areas 234

Cost of the Default Route in a Stub Area 236

The default-information originate Command 237

Other Stubby Area Types 238

OSPFv3 239

Configuring OSPFv3 240

Implementing OSPFv3 241

OSPFv3 for IPv4 and IPv6 246

Configuring Advanced OSPFv3 260

OSPFv3 Caveats 261

Summary 262

Review Questions 263

Chapter 4 Manipulating Routing Updates 267

Using Multiple IP Routing Protocols on a Network 267

Why Run Multiple Routing Protocols? 269

Running Multiple Routing Protocols 269

Administrative Distance 269

Multiple Routing Protocols Solutions 270

Implementing Route Redistribution 270

Defining Route Redistribution 270

Planning to Redistribute Routes 271

Redistributing Routes 271

Seed Metrics 272

Default Seed Metrics 273

Configuring and Verifying Basic Redistribution in IPv4 and IPv6 275

Redistributing OSPFv2 Routes into the EIGRP Routing Domain 276

Redistributing OSPFv3 Routes into the EIGRP for IPv6 Routing Domain 279

Redistributing EIGRP Routes into the OSPFv2 Routing Domain 281

Redistributing EIGRP for IPv6 Routes into the OSPFv3 Routing Domain 285

Types of Redistribution Techniques 287

One-Point Redistribution 287

Multipoint Redistribution 288

Redistribution Problems 289

Preventing Routing Loops in a Redistribution Environment 291

Verifying Redistribution Operation 292

Controlling Routing Update Traffic 292

Why Filter Routes? 292

Route Filtering Methods 293

Using Distribute Lists 294

Configuring Distribute Lists 294

Distribute List and ACL Example 295

Using Prefix Lists 297

Prefix List Characteristics 297

Configuring Prefix Lists 298

Distribute List and Prefix List Example 299

Prefix List Examples 300

Verifying Prefix Lists 301

Manipulating Redistribution Using ACLs, Prefix Lists, and Distribute Lists 302

Using Route Maps 305

Understanding Route Maps 305

Route Map Applications 305

Configuring Route Maps 306

Route Map Match and Set Statements 308

Configuring Route Redistribution Using Route Maps 310

Using Route Maps with Redistribution 310

Manipulating Redistribution Using Route Maps 311

Mutual Redistribution without Route Filtering 312

Mutual Redistribution with Route Maps 313

Change Administrative Distance to Enable Optimal Routing 315

Manipulating Redistribution Using Route Tagging 318

Caveats of Redistribution 319

Summary 320

References 323

Review Questions 323

Chapter 5 Path Control Implementation 327

Using Cisco Express Forwarding Switching 327

Control and Data Plane 328

Cisco Switching Mechanisms 328

Process and Fast Switching 332

Cisco Express Forwarding 333

Analyzing Cisco Express Forwarding 335

Verify the Content of the CEF Tables 335

Enable and Disable CEF by Interface and Globally 341

Understanding Path Control 343

The Need for Path Control 343

Implementing Path Control Using Policy-Based Routing 344

PBR Features 344

Steps for Configuring PBR 345

Configuring PBR 346

Verifying PBR 348

Configuring PBR Example 348

Implementing Path Control Using Cisco IOS IP SLAs 354

PBR and IP SLA 354

IP SLA Features 354

Steps for Configuring IP SLAs 356

Verifying Path Control Using IOS IP SLAs 360

Configuring IP SLA Example 361

Configuring PBR and IP SLA Example 364

Summary 369

References 370

Review Questions 370

Chapter 6 Enterprise Internet Connectivity 373

Planning Enterprise Internet Connectivity 374

Connecting Enterprise Networks to an ISP 374

Enterprise Connectivity Requirements 374

ISP Redundancy 375

Public IP Address Assignment 376

The Internet Assigned Numbers Authority 376

Regional Internet Registries 377

Public IP Address Space 377

Autonomous System Numbers 378

Establishing Single-Homed IPv4 Internet Connectivity 381

Configuring a Provider-Assigned IPv4 Address 381

DHCP Operation 382

Obtaining a Provider-Assigned IPv4 Address with DHCP 383

Configuring a Router as a DHCP Server and DHCP Relay Agent 384

NAT 385

Configuring Static NAT 388

Configuring Dynamic NAT 389

Configuring PAT 390

Limitations of NAT 392

NAT Virtual Interface 393

Configuring NAT Virtual Interface 393

Verifying NAT Virtual Interface 396

Establishing Single-Homed IPv6 Internet Connectivity 398

Obtaining a Provider-Assigned IPv6 Address 398

Manual Assignment 399

Configuring Basic IPv6 Internet Connectivity 399

Stateless Address Autoconfiguration 401

DHCPv6 Operation 402

Stateless DCHPv6 403

Stateful DHCPv6 404

DHCPv6 Prefix Delegation 405

NAT for IPv6 405

NAT64 405

NPTv6 405

IPv6 ACLs 405

IPv6 ACL Characteristics 406

Configuring IPv6 ACLs 406

Securing IPv6 Internet Connectivity 409

Improving Internet Connectivity Resilience 410

Drawbacks of a Single-Homed Internet Connectivity 410

Dual-Homed Internet Connectivity 410

Dual-Homed Connectivity Options 411

Configuring Best Path for Dual-Homed Internet Connectivity 411

Multihomed Internet Connectivity 413

Summary 415

References 417

Review Questions 418

Chapter 7 BGP Implementation 423

BGP Terminology, Concepts, and Operation 424

BGP Use Between Autonomous Systems 424

Comparison with Other Scalable Routing Protocols 425

BGP Path Vector Characteristics 426

BGP Characteristics 428

BGP Tables 430

BGP Message Types 431

Open and Keepalive Messages 431

Update Messages 433

Notification Messages 433

When to Use BGP 433

When Not to Use BGP 434

Implementing Basic BGP 435

BGP Neighbor Relationships 435

External BGP Neighbors 436

Internal BGP Neighbors 437

iBGP on All Routers in a Transit Path 438

Basic BGP Configuration Requirements 442

Entering BGP Configuration Mode 442

Defining BGP Neighbors and Activating BGP Sessions 443

Basic BGP Configuration and Verification 444

Configuring and Verifying an eBGP Session 445

Configuring and Verifying an iBGP Session 449

Advertising Networks in BGP and Verifying That They Are Propagated 450

Using the Next-Hop-Self Feature 457

Understanding and Troubleshooting BGP Neighbor States 458

BGP Session Resilience 460

Sourcing BGP from Loopback Address 461

eBGP Multihop 463

Resetting BGP Sessions 464

BGP Attributes and the Path-Selection Process 467