Brad Edgeworth, CCIE No. 31574 (R&S & SP), has been with Cisco since 2011, working as a Systems Engineer and a Technical Leader. Brad is a distinguished speaker at Cisco Live, where he has presented on IOS XR. Before joining Cisco, Brad worked as a network architect and consultant for various Fortune 500 companies. Brad's other certifications include Cisco Certified Design Professional (CCDP) and Microsoft Certified Systems Engineer (MCSE). Brad has been working in the IT field for the past 18 years, with an emphasis on enterprise and service provider environments from an architectural and operational perspective. Brad holds a bachelor of arts degree in computer systems management from St. Edward's University in Austin, Texas. Aaron Foss, CCIE No. 18761 (R&S & SP), is a High Touch Engineer with Cisco's Focused Technical Support (FTS) organization. He works with large service providers to troubleshoot issues relating to Multiprotocol Label Switching (MPLS), quality of service (QoS), and IP routing protocols. Aaron has more than 15 years of experience designing, deploying, and troubleshooting IP networks. He holds a bachelor of science degree in management information systems from Rochester Institute of Technology. Ramiro Garza Rios, CCIE No. 15469 (R&S, SP, and Security), is a Senior Network Consulting Engineer with Cisco Advanced Services. His current role consists of planning, designing, implementing, and optimizing next-generation (NGN) service provider networks in the United States. He has been with Cisco for more than 8 years and has 14 years of networking industry experience. Before joining Cisco, Ramiro was a Network Consulting and Presales Engineer for a Cisco Gold Partner in Mexico, where he was involved in the planning, design, and implementation of many enterprise and service provider networks. He holds a bachelor of science degree in electronic engineering from the Instituto Tecnologico de Reynosa and lives with his wife and four children in Cary, North Carolina.

Contents Foreword Introduction Part I Network Fundamentals Chapter 1 Introduction to the Operating Systems 1 IOS, IOS XE, and IOS XR Software Architecture 1 IOS 1 Kernel and OS Scheduling 2 Memory Management 2 Software Packaging 2 IOS XE 4 Kernel and OS Scheduling 4 Memory Management 4 IOS XR 5 Kernel and OS Scheduling 5 Memory Management 5 Software Packaging 6 Debugging 8 CLI and Configuration 8 IOS 9 User Mode 9 Privileged Mode 10 Global Configuration Mode 10 Configuration Archiving 11 Configuration Replace 13 IOS XR 14 Viewing Changes in the SysDB 17 Commit Label 18 Commit Replace 19 Failed Commits 20 Configuration Rollback 21 Commit Confirmed 22 Multiple Commit Options 23 Loading Files for Changes 24 Hierarchical Configuration 24 PWD 26 Root 26 Summary 27 References in This Chapter 27 Chapter 2 IPv4 Addressing 29 IP Fundamentals 29 Understanding Binary 31 Address Classes 34 Subnet Masks and Subnetting 35 Subnet Mask Purpose 36 Calculating Usable IP Addresses 37 Network Prefix Notation 38 Subnetting 38 Subnet Field 39 Subnet Math 41 Subnet Design 46 Classless Interdomain Routing 49 Classful Versus Classless Routing 50 Classful Routing 50 Classless Routing 53 Variable-Length Subnet Masks 55 Summarization 56 Private IP Addressing 58 Special IP Addresses 59 IPv4 Address Configuration 60 Wildcard Subnet Masks 62 Summary 64 References in This Chapter 65 Chapter 3 How a Router Works 67 IP Routing 67 Distance Vector Algorithms 69 Enhanced Distance Vector Algorithm 70 Link-State Algorithms 70 Path Vector Algorithm 71 Routing Table 72 Prefix Length 73 Administrative Distance 73 Metrics 75 Virtual Routing and Forwarding 76 IP Packet Switching 83 Process Switching 84 Cisco Express Forwarding 85 Software CEF 87 Hardware CEF 88 Planes of Operation 89 References in This Chapter 90 Part II Routing Protocols Chapter 4 Static Routing 91 Connected Networks 91 Secondary Connected Networks 94 Static Routing Fundamentals 94 Point-to-Point Interfaces 96 Broadcast Interfaces 98 Default Route 99 Floating Static Routing 103 Recursive Lookup 105 Multihop Routing 108 Single Recursive Lookup 108 Multiple Recursive Lookups 109 Problems with Static Route Recursion 112 Null Interface 116 Static VRF Routes 121 References in This Chapter 124 Chapter 5 EIGRP 125 EIGRP Fundamentals 125 EIGRP Neighbors 126 Inter-Router Communication 126 Forming EIGRP Neighbors 128 Classic EIGRP Autonomous System Configuration 131 IOS network Statement 132 IOS XR 134 Passive Interfaces 134 Sample Topology and Configuration 134 Confirmation of Interfaces 136 Verification of EIGRP Neighbor Adjacencies 139 Display of Installed EIGRP Routes 140 Router ID 141 EIGRP Terminology 142 Topology Table 143 Path Metric Calculation 145 Custom K Values 148 Interface Delay Settings 149 Load Balancing 151 EIGRP Wide Metrics 153 Failure Detection and Timers 155 Convergence 156 Stuck in Active 159 Stub 160 Design Considerations with EIGRP Stubs 164 Summarization 166 Interface-Specific Summarization 166 Summarization Metrics 171 Advertising a Default Route 172 Automatic Summarization 172 Authentication 174 Enabling Authentication on the interface 174 Key Chain Configuration 174 WAN Considerations 177 IP Bandwidth Percent 177 Split Horizon 179 Next-Hop Self 182 EIGRP Named Configuration 184 Address Family Instance Configuration 185 Address Family Interface Configuration 186 Address Family Topology Configuration 188 Summary 189 References in This Chapter 189 Chapter 6 OSPF 191 OSPF Fundamentals 191 Inter-Router Communication 193 OSPF Hello Packets 194 Router ID 195 Neighbors 196 Forming OSPF Neighbor Adjacencies 197 Basic OSPF Configuration 202 IOS network Statement 202 IOS Interface Specific 204 IOS XR 205 Passive Interfaces 205 Sample Topology and Configuration 206 Confirmation of Interfaces 208 Verification of OSPF Neighbor Adjacencies 209 Verification of OSPF Routes 211 Designated Router and Backup Designated Router 212 Designated Router Elections 214 DR and BDR Placement 216 Failure Detection 219 Hello Timer 219 Dead Interval Timer 219 Verifying OSPF Timers 220 OSPF Fast Packet Hellos 220 OSPF Network Types 221 Broadcast 221 Non-Broadcast 222 Point-to-Point Networks 224 Point-to-Multipoint Networks 225 Loopback Networks 229 Review of OSPF Network Types 231 OSPF Adjacency with Different OSPF Network Types 231 Link Costs 235 Authentication 236 IOS Support for OSPF Authentication 236 IOS XR Support for OSPF Authentication 236 Summary 239 References in This Chapter 240 Chapter 7 Advanced OSPF 241 Areas 241 Area ID 245 OSPF Route Types 246 External OSPF Routes 247 Link-State Announcements 249 LSA Age and Flooding 251 LSA Types 251 LSA Type 1: Router Link 252 LSA Type 2: Network Link 257 LSA Type 3: Summary Link 259 LSA Type 5: External Routes 263 LSA Type 4: ASBR Summary 265 LSA Type 7: NSSA External Summary 268 LSA Type Summary 270 OSPF Path Selection 270 Intra-Area Routes 271 Interarea Routes 272 External Route Selection 272 E1 and N1 External Routes 273 E2 and N2 External Routes 273 Equal Cost Multi-Path 274 Summarization of Routes 274 Interarea Summarization 276 External Summarization 280 Default Route 283 OSPF Stubby Areas 286 Stub Areas 286 Totally Stubby Areas 289 Not-So-Stubby Areas 292 Totally NSSA Areas 295 Virtual Links 298 Discontiguous Network 301 Multi-Area Adjacency 304 Prefix Suppression 308 Summary 313 References in This Chapter 314 Chapter 8 IS-IS 315 IS-IS Fundamentals 315 Areas 318 OSI Addressing 319 Inter-Domain Part 320 Domain Specific Part 321 NET Addressing 322 Inter-Router Communication 323 IS Protocol Header 325 TLVs 326 IS PDU Addressing 326 Hello Packets 327 Link-State Packets 329 LSP Lifetime 329 LSP ID 330 LSP Sequence 331 Attribute Fields 331 LSP Packet and TLVs 332 IS-IS Neighbor 333 Ethernet 333 Point-to-Point 338 Basic IS-IS Configuration 340 IOS 340 IOS XR 340 Sample Topology and Configuration 341 Confirmation of IS-IS Interfaces 343 Verification of IS-IS Neighbor Adjacencies 346 Verification of IS-IS Routes 347 Designated Intermediate System 348 DIS Elections 351 DIS Placement 352 Point-to-Point Adjacency on Broadcast Media 353 Link State Packet Database 355 Viewing the LSPDB 356 Non-Pseudonode LSPs 357 Pseudonode LSPs 358 Building the Topology 359 Viewing the Topology 360 SPF Calculations 361 Passive Interfaces 362 Removal of Hello Padding 364 Failure Detection 366 Hello Timer 366 Hello Multiplier and Holding Timer 367 Authentication 367 IS-IS Hello Authentication 367 IS-IS LSP Authentication 368 Summary 371 References in This Chapter 372 Chapter 9 Advanced IS-IS 373 Advanced IS-IS Routing 373 Route Leaking 377 Backbone Continuity 380 Loop Prevention 382 Router-Specific IS-IS Levels 384 Interface Specific IS-IS Levels 385 Path Selection 386 Equal Cost Multi-Path 387 Interface Metrics 387 Overload Bit 394 Summarization 396 Default Routes 400 Prefix Suppression 401 Summary 405 References in This Chapter 406 Chapter 10 Border Gateway Protocol (BGP) 407 BGP Fundamentals 408 Autonomous System Numbers 408 Path Attributes 409 Loop Prevention 409 Address Families 410 Inter-Router Communication 410 Open Messages 412 Hold Time 412 BGP Identifier 413 Keepalive Messages 413 Update Messages 413 Notification Messages 414 BGP Sessions 415 BGP Neighbor States 415 Idle State 415 Connect State 415 Active State 416 OpenSent State 416 OpenConfirm State 417 Established State 417 Basic BGP Configuration 418 IOS 419 IOS XR 420 Verification of BGP Sessions 421 Prefix Advertisement 425 Receiving and Viewing Routes 427 iBGP 431 iBGP Full-Mesh Requirement 432 Peering via Loopback Addresses 433 eBGP 438 eBGP and iBGP Topologies 442 Next-Hop Manipulation 444 iBGP Scalability 446 Route Reflectors 446 Loop Prevention in Route Reflectors 451 Out-of-Band Route Reflectors 453 Confederations 453 Failure Detection 459 Security 459 eBGP Multihop 459 TTL Security 461 Summary 463 References in This Chapter 465 Part III Advanced Routing Techniques Chapter 11 Route Maps and Route Policy 467 Access Control Lists 467 Standard ACLs 468 Extended ACLs 469 IGP Network Selection 469 BGP Network Selection 470 Prefix Matching 471 Prefix Lists 473 Prefix Sets 474 Regular Expressions 475 _ (Underscore) 477 ^ (Caret) 478 $ (Dollar Sign) 478 [ ] (Brackets) 479 - (Hyphen) 479

This is the first single source for mastering all the routing protocols and configurations needed to work with Cisco IOS, IOS XE, and IOS XR operating systems. Bringing together content previously spread across multiple sources and Cisco Press titles, it covers updated standards and features found in enterprise and service provider environments.