-
Cisco IOS XR Routing Configuration Guide for the Cisco CRS
Router,Release 4.3.x
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Text Part Number: OL-28410-03
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C O N T E N T S
P r e f a c e Preface xxv
Changes to This Document xxv
Obtaining Documentation and Submitting a Service Request xxv
C H A P T E R 1 New and Changed Feature Information in Cisco IOS
XR Release 4.3.x 1
New and Changed Routing Features 1
C H A P T E R 2 Implementing BGP 9
Prerequisites for Implementing BGP 12
Information About Implementing BGP 12
BGP Functional Overview 12
BGP Router Identifier 13
BGP Default Limits 13
BGP Next Hop Tracking 14
Next Hop as the IPv6 Address of Peering Interface 15
Scoped IPv4/VPNv4 Table Walk 16
Reordered Address Family Processing 16
New Thread for Next-Hop Processing 16
show, clear, and debug Commands 16
Autonomous System Number Formats in BGP 17
2-byte Autonomous System Number Format 17
4-byte Autonomous System Number Format 17
as-format Command 17
BGP Configuration 17
Configuration Modes 18
Router Configuration Mode 18
Router Address Family Configuration Mode 18
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Neighbor Configuration Mode 18
Neighbor Address Family Configuration Mode 18
VRF Configuration Mode 18
VRF Address Family Configuration Mode 19
VRF Neighbor Configuration Mode 19
VRF Neighbor Address Family Configuration Mode 19
VPNv4 Address Family Configuration Mode 19
VPNv6 Address Family Configuration Mode 19
L2VPN Address Family Configuration Mode 19
Neighbor Submode 20
Configuration Templates 20
Template Inheritance Rules 22
Viewing Inherited Configurations 25
show bgp neighbors 25
show bgp af-group 26
show bgp session-group 28
show bgp neighbor-group 28
No Default Address Family 30
Routing Policy Enforcement 30
Table Policy 32
Update Groups 32
BGP Update Generation and Update Groups 33
BGP Update Group 33
BGP Cost Community 33
How BGP Cost Community Influences the Best Path Selection
Process 33
Cost Community Support for Aggregate Routes and Multipaths
34
Influencing Route Preference in a Multiexit IGP Network 36
BGP Cost Community Support for EIGRP MPLS VPN PE-CE with
Back-door
Links 36
Adding Routes to the Routing Information Base 38
BGP Best Path Algorithm 38
Comparing Pairs of Paths 38
Order of Comparisons 40
Best Path Change Suppression 41
Administrative Distance 41
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Multiprotocol BGP 43
Route Dampening 45
Minimizing Flapping 46
BGP Routing Domain Confederation 46
BGP Route Reflectors 46
Default Address Family for show Commands 50
MPLS VPN Carrier Supporting Carrier 50
BGP Keychains 51
BGP Nonstop Routing 51
BGP Best-External Path 53
BGP Prefix Independent Convergence Unipath Primary/Backup 54
BGP Local Label Retention 54
BGP Over GRE Interfaces 55
Command Line Interface (CLI) Consistency for BGP Commands 55
BGP Additional Paths 55
iBGP Multipath Load Sharing 55
Accumulated Interior Gateway Protocol Attribute 56
Per VRF and Per CE Label for IPv6 Provider Edge 56
Constrained Route Distribution for BGP/MPLS Internet Protocol
VPNs 57
Constrained Route Distribution Benefits 57
BGP RT-constrain SAFIrt-filter 57
Selective VRF Download 58
Line Card Roles and Filters in Selective VRF Download 58
BGP Accept Own 59
BGP DMZ Link Bandwidth for Unequal Cost Recursive Load Balancing
61
BFD Multihop Support for BGP 61
BGP Multi-Instance/Multi-AS Support 61
BGP Prefix Origin Validation Based on RPKI 62
BGP 3107 PIC Updates for Global Prefixes 62
BGP Prefix Independent Convergence for RIB and FIB 63
BGP Update Message Error Handling 63
BGP Attribute Filtering 63
BGP Attribute Filter Actions 64
BGP Error Handling and Attribute Filtering Syslog Messages
64
BGP VRF Dynamic Route Leaking 65
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How to Implement BGP 65
Enabling BGP Routing 65
Configuring a Routing Domain Confederation for BGP 68
Resetting an eBGP Session Immediately Upon Link Failure 70
Logging Neighbor Changes 70
Adjusting BGP Timers 70
Changing the BGP Default Local Preference Value 72
Configuring the MED Metric for BGP 73
Configuring BGP Weights 74
Tuning the BGP Best-Path Calculation 75
Indicating BGP Back-door Routes 77
Configuring Aggregate Addresses 78
Redistributing iBGP Routes into IGP 80
Redistributing Prefixes into Multiprotocol BGP 81
Configuring BGP Route Dampening 83
Applying Policy When Updating the Routing Table 88
Setting BGP Administrative Distance 90
Configuring a BGP Neighbor Group and Neighbors 91
Configuring a Route Reflector for BGP 94
Configuring BGP Route Filtering by Route Policy 96
Configuring BGP Next-Hop Trigger Delay 98
Disabling Next-Hop Processing on BGP Updates 99
Configuring BGP Community and Extended-Community Advertisements
100
Configuring the BGP Cost Community 103
Configuring Software to Store Updates from a Neighbor 107
Configuring a VPN Routing and Forwarding Instance in BGP 109
Defining Virtual Routing and Forwarding Tables in Provider Edge
Routers 109
Configuring the Route Distinguisher 111
Configuring BGP to Advertise VRF Routes for Multicast VPN from
PE to PE 113
Advertising VRF Routes for MVPNv4 from PE to PE 114
Advertising VRF Routes for MVPNv6 from PE to PE 119
Configuring PE-PE or PE-RR Interior BGP Sessions 124
Configuring Route Reflector to Hold Routes That Have a Defined
Set of RT
Communities 126
Configuring BGP as a PE-CE Protocol 128
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Redistribution of IGPs to BGP 132
Configuring Keychains for BGP 134
Configuring an MDT Address Family Session in BGP 136
Disabling a BGP Neighbor 140
Resetting Neighbors Using BGP Inbound Soft Reset 141
Resetting Neighbors Using BGP Outbound Soft Reset 142
Resetting Neighbors Using BGP Hard Reset 143
Clearing Caches, Tables, and Databases 144
Displaying System and Network Statistics 145
Displaying BGP Process Information 147
Monitoring BGP Update Groups 148
Configuring BGP Nonstop Routing 149
Configuring Best-External Path Advertisement 150
Installing Primary Backup Path for Prefix Independent
Convergence (PIC) 152
Retaining Allocated Local Label for Primary Path 153
Configuring BGP Additional Paths 155
Configuring iBGP Multipath Load Sharing 157
Originating Prefixes with AiGP 158
Configuring BGP Accept Own 160
Enabling BGP Unequal Cost Recursive Load Balancing 161
Configuring RPKI Cache-server 163
Configuring RPKI Prefix Validation 166
Configuring RPKI Bestpath Computation 168
Configuring VRF Dynamic Route Leaking 169
Configuration Examples for Implementing BGP 171
Enabling BGP: Example 171
Displaying BGP Update Groups: Example 173
BGP Neighbor Configuration: Example 173
BGP Confederation: Example 174
BGP Route Reflector: Example 176
BGP MDT Address Family Configuration: Example 176
BGP Nonstop Routing Configuration: Example 176
Best-External Path Advertisement Configuration: Example 177
Primary Backup Path Installation: Example 177
Allocated Local Label Retention: Example 177
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iBGP Multipath Loadsharing Configuration: Example 177
Originating Prefixes With AiGP: Example 177
BGP Accept Own Configuration: Example 178
BGP Unequal Cost Recursive Load Balancing: Example 179
VRF Dynamic Route Leaking Configuration: Example 181
Where to Go Next 181
Additional References 181
C H A P T E R 3 Implementing BFD 185
Prerequisites for Implementing BFD 188
Restrictions for Implementing BFD 188
Information About BFD 189
Differences in BFD in Cisco IOS XR Software and Cisco IOS
Software 189
BFD Modes of Operation 190
BFD Packet Information 191
BFD Source and Destination Ports 191
BFD Packet Intervals and Failure Detection 191
BFD Packet Intervals on Physical Interfaces 191
BFD Packet Intervals on Bundle Member Links 192
Control Packet Failure Detection In Asynchronous Mode 192
Echo Packet Failure Detection In Asynchronous Mode 192
Echo Failure Detection Examples 193
Summary of Packet Intervals and Failure Detection Times for BFD
on Bundle
Interfaces 194
Echo Packet Latency 195
Priority Settings for BFD Packets 195
BFD for IPv4 196
BFD for IPv6 197
BFD on Bundled VLANs 197
BFD Over Member Links on Link Bundles 199
Overview of BFD State Change Behavior on Member Links and Bundle
Status 199
BFD Multipath Sessions 201
BFD for MultiHop Paths 201
Setting up BFD Multihop 202
Limitations of BFD 202
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Bidirectional Forwarding Detection over Logical Bundle 202
BFD IPv6 Multihop 202
BFD over MPLS Traffic Engineering LSPs 203
BFD over Satellite Interfaces 204
Limitations 204
How to Configure BFD 204
BFD Configuration Guidelines 204
Configuring BFD Under a Dynamic Routing Protocol or Using a
Static Route 205
Enabling BFD on a BGP Neighbor 205
Enabling BFD for OSPF on an Interface 207
Enabling BFD for OSPFv3 on an Interface 209
Enabling BFD on a Static Route 210
Configuring BFD on Bundle Member Links 212
Prerequisites for Configuring BFD on Bundle Menmber Links
212
Specifying the BFD Destination Address on a Bundle 212
Enabling BFD Sessions on Bundle Members 213
Configuring the Minimum Thresholds for Maintaining an Active
Bundle 214
Configuring BFD Packet Transmission Intervals and Failure
Detection Times on a
Bundle 216
Configuring Allowable Delays for BFD State Change Notifications
Using Timers on a
Bundle 217
Enabling Echo Mode to Test the Forwarding Path to a BFD Peer
219
Overriding the Default Echo Packet Source Address 219
Specifying the Echo Packet Source Address Globally for BFD
219
Specifying the Echo Packet Source Address on an Individual
Interface or Bundle 220
Configuring BFD Session Teardown Based on Echo Latency Detection
222
Delaying BFD Session Startup Until Verification of Echo Path and
Latency 223
Disabling Echo Mode 224
Disabling Echo Mode on a Router 225
Disabling Echo Mode on an Individual Interface or Bundle 226
Minimizing BFD Session Flapping Using BFD Dampening 227
Enabling and Disabling IPv6 Checksum Support 228
Enabling and Disabling IPv6 Checksum Calculations for BFD on a
Router 228
Enabling and Disabling IPv6 Checksum Calculations for BFD on an
Individual Interface
or Bundle 229
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Clearing and Displaying BFD Counters 231
Configuring Coexistence Between BFD over Bundle (BoB) and BFD
over Logical Bundle
(BLB) 231
Configuring BFD over MPLS Traffic Engineering LSPs 233
Enabling BFD Parameters for BFD over TE Tunnels 233
Configuring BFD Bring up Timeout 234
Configuring BFD Dampening for TE Tunnels 235
Configuring Periodic LSP Ping Requests 237
Configuring BFD at the Tail End 238
Configuring BFD over LSP Sessions on Line Cards 239
Configuration Examples for Configuring BFD 241
BFD Over BGP: Example 241
BFD Over OSPF: Examples 241
BFD Over Static Routes: Examples 242
BFD on Bundled VLANs: Example 242
BFD on Bundle Member Links: Examples 243
Echo Packet Source Address: Examples 244
Echo Latency Detection: Examples 245
Echo Startup Validation: Examples 245
BFD Echo Mode Disable: Examples 246
BFD Dampening: Examples 246
BFD IPv6 Checksum: Examples 246
BFD Peers on Routers Running Cisco IOS and Cisco IOS XR
Software: Example 247
BFD over MPLS TE LSPs: Examples 247
BFD over MPLS TE Tunnel Head-end Configuration: Example 248
BFD over MPLS TE Tunnel Tail-end Configuration: Example 248
Where to Go Next 248
Additional References 248
Related Documents 249
Standards 249
RFCs 249
MIBs 249
Technical Assistance 250
C H A P T E R 4 Implementing EIGRP 251
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Prerequisites for Implementing EIGRP 252
Restrictions for Implementing EIGRP 252
Information About Implementing EIGRP 252
EIGRP Functional Overview 253
EIGRP Features 253
EIGRP Components 253
EIGRP Configuration Grouping 254
EIGRP Configuration Modes 255
EIGRP Interfaces 256
Redistribution for an EIGRP Process 256
Metric Weights for EIGRP Routing 256
Mismatched K Values 257
Goodbye Message 257
Percentage of Link Bandwidth Used for EIGRP Packets 258
Floating Summary Routes for an EIGRP Process 258
Split Horizon for an EIGRP Process 260
Adjustment of Hello Interval and Hold Time for an EIGRP Process
261
Stub Routing for an EIGRP Process 261
Route Policy Options for an EIGRP Process 262
EIGRP Layer 3 VPN PE-CE Site-of-Origin 263
Router Interoperation with the Site-of-Origin Extended Community
263
IPv6 and IPv6 VPN Provider Edge Support over MPLS and IP 264
EIGRP v4/v6 Authentication Using Keychain 264
EIGRP Wide Metric Computation 264
How to Implement EIGRP 265
Enabling EIGRP Routing 265
Configuring Route Summarization for an EIGRP Process 267
Redistributing Routes for EIGRP 269
Creating a Route Policy and Attaching It to an EIGRP Process
271
Configuring Stub Routing for an EIGRP Process 273
Configuring EIGRP as a PE-CE Protocol 275
Redistributing BGP Routes into EIGRP 277
Monitoring EIGRP Routing 279
Configuring an EIGRP Authentication Keychain 281
Configuring an Authentication Keychain for an IPv4/IPv6
Interface on a Default VRF 281
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Configuring an Authentication Keychain for an IPv4/IPv6
Interface on a Nondefault
VRF 283
Configuration Examples for Implementing EIGRP 284
Configuring a Basic EIGRP Configuration: Example 284
Configuring an EIGRP Stub Operation: Example 285
Configuring an EIGRP PE-CE Configuration with Prefix-Limits:
Example 285
Configuring an EIGRP Authentication Keychain: Example 286
Additional References 286
C H A P T E R 5 Implementing IS-IS 289
Prerequisites for Implementing IS-IS 291
Restrictions for Implementing IS-IS 291
Information About Implementing IS-IS 291
IS-IS Functional Overview 291
Key Features Supported in the Cisco IOS XR IS-IS Implementation
291
IS-IS Configuration Grouping 292
IS-IS Configuration Modes 292
Router Configuration Mode 292
Router Address Family Configuration Mode 292
Interface Configuration Mode 293
Interface Address Family Configuration Mode 293
IS-IS Interfaces 293
Multitopology Configuration 293
IPv6 Routing and Configuring IPv6 Addressing 294
Limit LSP Flooding 294
Flood Blocking on Specific Interfaces 294
Mesh Group Configuration 294
Maximum LSP Lifetime and Refresh Interval 295
Single-Topology IPv6 Support 295
Multitopology IPv6 Support 295
IS-IS Authentication 295
Nonstop Forwarding 296
Multi-Instance IS-IS 297
Multiprotocol Label Switching Traffic Engineering 297
Overload Bit on Router 297
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Overload Bit Configuration During Multitopology Operation
298
IS-IS Overload Bit Avoidance 298
Default Routes 298
Attached Bit on an IS-IS Instance 298
IS-IS Support for Route Tags 299
Multicast-Intact Feature 299
Multicast Topology Support Using IS-IS 299
MPLS Label Distribution Protocol IGP Synchronization 300
MPLS LDP-IGP Synchronization Compatibility with LDP Graceful
Restart 300
MPLS LDP-IGP Synchronization Compatibility with IGP Nonstop
Forwarding 300
Label Distribution Protocol IGP Auto-configuration 301
MPLS TE Forwarding Adjacency 301
MPLS TE Interarea Tunnels 301
IP Fast Reroute 301
IS-IS Over GRE Interfaces 302
Unequal Cost Multipath Load-balancing for IS-IS 302
How to Implement IS-IS 302
Enabling IS-IS and Configuring Level 1 or Level 2 Routing
303
Configuring Single Topology for IS-IS 305
Configuring Multitopology Routing 309
Restrictions for Configuring Multitopology Routing 309
Information About Multitopology Routing 310
Configuring a Global Topology and Associating It with an
Interface 310
Enabling an IS-IS Topology 311
Placing an Interface in a Topology in IS-IS 313
Configuring a Routing Policy 314
Configuring Multitopology for IS-IS 315
Controlling LSP Flooding for IS-IS 316
Configuring Nonstop Forwarding for IS-IS 320
Configuring Authentication for IS-IS 322
Configuring Keychains for IS-IS 323
Configuring MPLS Traffic Engineering for IS-IS 325
Tuning Adjacencies for IS-IS 327
Setting SPF Interval for a Single-Topology IPv4 and IPv6
Configuration 330
Customizing Routes for IS-IS 332
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Configuring MPLS LDP IS-IS Synchronization 335
Enabling Multicast-Intact 337
Tagging IS-IS Interface Routes 338
Setting the Priority for Adding Prefixes to the RIB 340
Configuring IP/LDP Fast Reroute 341
Configuring IS-IS Overload Bit Avoidance 344
Configuration Examples for Implementing IS-IS 345
Configuring Single-Topology IS-IS for IPv6: Example 345
Configuring Multitopology IS-IS for IPv6: Example 345
Redistributing IS-IS Routes Between Multiple Instances: Example
346
Tagging Routes: Example 346
Configuring IS-IS Overload Bit Avoidance: Example 347
Where to Go Next 347
Additional References 347
C H A P T E R 6 Implementing OSPF 351
Prerequisites for Implementing OSPF 353
Information About Implementing OSPF 354
OSPF Functional Overview 354
Key Features Supported in the Cisco IOS XR Software OSPF
Implementation 355
Comparison of Cisco IOS XR Software OSPFv3 and OSPFv2 356
OSPF Hierarchical CLI and CLI Inheritance 356
OSPF Routing Components 357
Autonomous Systems 357
Areas 357
Backbone Area 358
Stub Area 358
Not-so-Stubby Area 358
Routers 358
Area Border Routers 358
Autonomous System Boundary Routers (ASBR) 359
Interior Routers 359
OSPF Process and Router ID 359
Supported OSPF Network Types 360
Route Authentication Methods for OSPF 360
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Plain Text Authentication 360
MD5 Authentication 360
Authentication Strategies 361
Key Rollover 361
Neighbors and Adjacency for OSPF 361
Designated Router (DR) for OSPF 361
Default Route for OSPF 362
Link-State Advertisement Types for OSPF Version 2 362
Link-State Advertisement Types for OSPFv3 363
Virtual Link and Transit Area for OSPF 364
OSPFv2 Sham Link Support for MPLS VPN 364
OSPF SPF Prefix Prioritization 366
Route Redistribution for OSPF 368
OSPF Shortest Path First Throttling 368
Nonstop Forwarding for OSPF Version 2 369
Graceful Restart for OSPFv3 369
Modes of Graceful Restart Operation 370
Restart Mode 370
Helper Mode 370
Graceful Restart Requirements and Restrictions 371
Warm Standby and Nonstop Routing for OSPF Version 2 372
Warm Standby for OSPF Version 3 372
Multicast-Intact Support for OSPF 372
Load Balancing in OSPF Version 2 and OSPFv3 373
Multi-Area Adjacency for OSPF Version 2 373
Label Distribution Protocol IGP Auto-configuration for OSPF
374
OSPF Authentication Message Digest Management 374
GTSM TTL Security Mechanism for OSPF 375
Path Computation Element for OSPFv2 375
OSPF Queue Tuning Parameters 375
OSPF IP Fast Reroute Loop Free Alternate 376
OSPF Over GRE Interfaces 376
Management Information Base (MIB) for OSPFv3 376
VRF-lite Support for OSPFv2 376
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OSPFv3 Timers Link-state Advertisements and Shortest Path First
Throttle Default Values
Update 377
How to Implement OSPF 377
Enabling OSPF 377
Configuring Stub and Not-So-Stubby Area Types 379
Configuring Neighbors for Nonbroadcast Networks 382
Configuring Authentication at Different Hierarchical Levels for
OSPF Version 2 387
Controlling the Frequency That the Same LSA Is Originated or
Accepted for OSPF 390
Creating a Virtual Link with MD5 Authentication to Area 0 for
OSPF 392
Examples 397
Summarizing Subnetwork LSAs on an OSPF ABR 397
Redistributing Routes from One IGP into OSPF 399
Configuring OSPF Shortest Path First Throttling 402
Examples 404
Configuring Nonstop Forwarding Specific to Cisco for OSPF
Version 2 405
Configuring OSPF Version 2 for MPLS Traffic Engineering 407
Examples 409
Configuring OSPFv3 Graceful Restart 411
Displaying Information About Graceful Restart 413
Configuring an OSPFv2 Sham Link 414
Enabling Nonstop Routing for OSPFv2 417
Enabling Nonstop Routing for OSPFv3 418
Configuring OSPF SPF Prefix Prioritization 419
Enabling Multicast-intact for OSPFv2 421
Associating Interfaces to a VRF 422
Configuring OSPF as a Provider Edge to Customer Edge (PE-CE)
Protocol 424
Creating Multiple OSPF Instances (OSPF Process and a VRF)
426
Configuring Multi-area Adjacency 428
Configuring Label Distribution Protocol IGP Auto-configuration
for OSPF 430
Configuring LDP IGP Synchronization: OSPF 431
Configuring Authentication Message Digest Management for OSPF
432
Examples 434
Configuring Generalized TTL Security Mechanism (GTSM) for OSPF
435
Examples 437
Verifying OSPF Configuration and Operation 438
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Configuring OSPF Queue Tuning Parameters 440
Configuring IP Fast Reroute Loop-free Alternate 441
Enabling IPFRR LFA 441
Excluding an Interface From IP Fast Reroute Per-link Computation
443
Configuration Examples for Implementing OSPF 444
Cisco IOS XR Software for OSPF Version 2 Configuration: Example
444
CLI Inheritance and Precedence for OSPF Version 2: Example
445
MPLS TE for OSPF Version 2: Example 446
ABR with Summarization for OSPFv3: Example 446
ABR Stub Area for OSPFv3: Example 447
ABR Totally Stub Area for OSPFv3: Example 447
Configuring OSPF SPF Prefix Prioritization: Example 447
Route Redistribution for OSPFv3: Example 448
Virtual Link Configured Through Area 1 for OSPFv3: Example
448
Virtual Link Configured with MD5 Authentication for OSPF Version
2: Example 449
VPN Backbone and Sham Link Configured for OSPF Version 2:
Example 449
OSPF Queue Tuning Parameters Configuration: Example 451
Where to Go Next 451
Additional References 451
C H A P T E R 7 Implementing and Monitoring RIB 455
Prerequisites for Implementing RIB 456
Information About RIB Configuration 456
Overview of RIB 456
RIB Data Structures in BGP and Other Protocols 457
RIB Administrative Distance 457
RIB Support for IPv4 and IPv6 458
RIB Statistics 458
IPv6 Provider Edge IPv6 and IPv6 VPN Provider Edge Transport
over MPLS 458
IP Fast Reroute 459
RIB Quarantining 459
Route and Label Consistency Checker (RCC and LCC) 459
How to Deploy and Monitor RIB 460
Verifying RIB Configuration Using the Routing Table 460
Verifying Networking and Routing Problems 461
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Disabling RIB Next-hop Dampening 462
Configuring RCC and LCC 463
Enabling RCC and LCC On-demand Scan 463
Enabling RCC and LCC Background Scan 464
Configuration Examples for RIB Monitoring 466
Output of show route Command: Example 466
Output of show route backup Command: Example 467
Output of show route best-local Command: Example 467
Output of show route connected Command: Example 467
Output of show route local Command: Example 467
Output of show route longer-prefixes Command: Example 468
Output of show route next-hop Command: Example 468
Enabling RCC and LCC: Example 468
Where to Go Next 469
Additional References 469
C H A P T E R 8 Implementing RIP 471
Prerequisites for Implementing RIP 472
Information About Implementing RIP 472
RIP Functional Overview 472
Split Horizon for RIP 473
Route Timers for RIP 473
Route Redistribution for RIP 473
Default Administrative Distances for RIP 474
Routing Policy Options for RIP 475
Authentication Using Keychain in RIP 475
In-bound RIP Traffic on an Interface 476
Out-bound RIP Traffic on an Interface 477
How to Implement RIP 477
Enabling RIP 477
Customizing RIP 479
Control Routing Information 481
Creating a Route Policy for RIP 483
Configuring RIP Authentication Keychain 485
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Configuring RIP Authentication Keychain for IPv4 Interface on a
Non-default VRF 485
Configuring RIP Authentication Keychain for IPv4 Interface on
Default VRF 487
Configuration Examples for Implementing RIP 489
Configuring a Basic RIP Configuration: Example 489
Configuring RIP on the Provider Edge: Example 489
Adjusting RIP Timers for each VRF Instance: Example 490
Configuring Redistribution for RIP: Example 490
Configuring Route Policies for RIP: Example 491
Configuring Passive Interfaces and Explicit Neighbors for RIP:
Example 491
Controlling RIP Routes: Example 492
Configuring RIP Authentication Keychain: Example 492
Additional References 492
C H A P T E R 9 Implementing Routing Policy 495
Prerequisites for Implementing Routing Policy 497
Restrictions for Implementing Routing Policy 497
Information About Implementing Routing Policy 497
Routing Policy Language 497
Routing Policy Language Overview 498
Routing Policy Language Structure 498
Names 498
Sets 499
as-path-set 500
community-set 501
extcommunity-set 501
prefix-set 504
Enhanced Prefix-length Manipulation 505
rd-set 506
Routing Policy Language Components 506
Routing Policy Language Usage 507
Routing Policy Configuration Basics 509
Policy Definitions 509
Parameterization 510
Parameterization at Attach Points 511
Global Parameterization 511
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Semantics of Policy Application 512
Boolean Operator Precedence 512
Multiple Modifications of the Same Attribute 512
When Attributes Are Modified 513
Default Drop Disposition 513
Control Flow 514
Policy Verification 514
Range Checking 515
Incomplete Policy and Set References 515
Attached Policy Modification 515
Verification of Attribute Comparisons and Actions 516
Policy Statements 516
Remark 516
Disposition 516
Action 518
If 518
Boolean Conditions 520
apply 521
Attach Points 521
BGP Policy Attach Points 522
Additional-Path 522
Aggregation 522
Dampening 523
Default Originate 523
Neighbor Export 524
Neighbor Import 524
Network 525
Redistribute 525
Show BGP 526
Table Policy 527
Import 527
Export 528
Retain Route-Target 529
Label-Mode 529
Allocate-Label 530
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Neighbor-ORF 530
Next-hop 531
Clear-Policy 531
Debug 532
BGP Attributes and Operators 532
OSPF Policy Attach Points 548
Default-Information Originate 548
Redistribute 548
Area-in 549
Area-out 549
SPF Prefix-priority 550
OSPF Attributes and Operators 550
Distribute-list in 551
OSPFv3 Policy Attach Points 552
Default-Information Originate 552
Redistribute 552
OSPFv3 Attributes and Operators 553
IS-IS Policy Attach Points 553
Redistribute 553
Default-Information Originate 554
Inter-area-propagate 554
IS-IS Attributes and Operators 555
EIGRP Policy Attach Points 555
Default-Accept-In 556
Default-Accept-Out 556
Policy-In 556
Policy-Out 557
If-Policy-In 557
If-Policy-Out 557
Redistribute 557
EIGRP Attributes and Operators 558
RIP Policy Attach Points 559
Default-Information Originate 559
Redistribute 559
Global-Inbound 560
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Global-Outbound 560
Interface-Inbound 560
Interface-Outbound 560
RIP Attributes and Operators 560
PIM Policy Attach Points 562
rpf-topology 562
PIM Attributes and Operators 563
Attached Policy Modification 563
Nonattached Policy Modification 563
Editing Routing Policy Configuration Elements 564
Editing Routing Policy Configuration Elements Using the Nano
Editor 564
Editing Routing Policy Configuration Elements Using the Emacs
Editor 564
Editing Routing Policy Configuration Elements Using the Vim
Editor 565
Editing Routing Policy Configuration Elements Using the CLI
566
Editing Routing Policy Language set elements Using XML 566
Hierarchical Policy Conditions 566
Apply Condition Policies 566
Behavior of pass/drop/done RPL Statements for Simple
Hierarchical Policies 567
Behavior of pass/drop/done RPL Statements for Hierarchical
Policy
Conditions 568
Nested Wildcard Apply Policy 569
VRF Import Policy Enhancement 569
Flexible L3VPN Label Allocation Mode 570
How to Implement Routing Policy 570
Defining a Route Policy 570
Attaching a Routing Policy to a BGP Neighbor 571
Modifying a Routing Policy Using a Text Editor 573
Configuration Examples for Implementing Routing Policy 574
Routing Policy Definition: Example 574
Simple Inbound Policy: Example 574
Modular Inbound Policy: Example 575
Translating Cisco IOS Route Maps to Cisco IOS XR Routing Policy
Language:
Example 576
Additional References 576
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C H A P T E R 1 0 Implementing Static Routes 579
Prerequisites for Implementing Static Routes 580
Restrictions for Implementing Static Routes 580
Information About Implementing Static Routes 580
Static Route Functional Overview 580
Default Administrative Distance 581
Directly Connected Routes 581
Recursive Static Routes 582
Fully Specified Static Routes 582
Floating Static Routes 583
Default VRF 583
IPv4 and IPv6 Static VRF Routes 583
How to Implement Static Routes 583
Configuring a Static Route 583
Configuring a Static Route Under Multicast SAFI 585
Configuring a Floating Static Route 587
Configuring Static Routes Between PE-CE Routers 588
Changing the Maximum Number of Allowable Static Routes 589
Associating a VRF with a Static Route 591
Configuration Examples 592
Configuring Traffic Discard: Example 592
Configuring a Fixed Default Route: Example 593
Configuring a Floating Static Route: Example 593
Configuring a Static Route Between PE-CE Routers: Example
593
Where to Go Next 593
Additional References 594
C H A P T E R 1 1 Implementing RCMD 597
Route Convergence Monitoring and Diagnostics 597
Configuring Route Convergence Monitoring and Diagnostics 598
Route Convergence Monitoring and Diagnostics Prefix Monitoring
601
Route Convergence Monitoring and Diagnostics OSPF Type 3/5/7
Link-state Advertisements
Monitoring 601
Enabling RCMD Monitoring for IS-IS Prefixes 601
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Enabling RCMD Monitoring for OSPF Prefixes 603
Enabling RCMD Monitoring for Type 3/5/7 OSPF LSAs 604
Enabling RCMD Monitoring for IS-IS Prefixes: Example 605
Enabling RCMD Monitoring for OSPF Prefixes: Example 605
Enabling RCMD Monitoring for Type 3/5/7 OSPF LSAs: Example
606
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Preface
The Cisco IOS XR Routing Configuration Guide for the Cisco CRS
Router preface contains these sections:
Changes to This Document, page xxv
Obtaining Documentation and Submitting a Service Request, page
xxv
Changes to This DocumentThis table lists the technical changes
made to this document since it was first published.
Table 1: Changes to This Document
Change SummaryDateRevision
Republished with documentationupdates for Cisco IOS XR
Release4.3.2 features.
September 2013OL-28410-03
Republished with documentationupdates for Cisco IOS XR
Release4.3.1 features.
May, 2013OL-28410-02
Initial release of this document.December, 2012OL-28410-01
Obtaining Documentation and Submitting a Service RequestFor
information on obtaining documentation, using the Cisco Bug Search
Tool (BST), submitting a servicerequest, and gathering additional
information, seeWhat's New in Cisco Product Documentation, at:
http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html.
Subscribe toWhat's New in Cisco Product Documentation, which
lists all new and revised Cisco technicaldocumentation, as an RSS
feed and deliver content directly to your desktop using a reader
application. TheRSS feeds are a free service.
Cisco IOS XR Routing Configuration Guide for the Cisco CRS
Router, Release 4.3.x OL-28410-03 xxv
-
Cisco IOS XR Routing Configuration Guide for the Cisco CRS
Router, Release 4.3.xxxvi OL-28410-03
PrefaceObtaining Documentation and Submitting a Service
Request
-
C H A P T E R 1New and Changed Feature Information in CiscoIOS
XR Release 4.3.x
This table summarizes the new and changed feature information
for the Cisco IOS XR Routing ConfigurationGuide for the Cisco CRS
Router, and tells you where they are documented.
For a complete list of new and changed features in Cisco IOS XR
Software, Release 4.3.x, see the New andChanged Features in Cisco
IOS XR Software, Release 4.3.x for Cisco CRS Router document.
New and Changed Routing Features, page 1
New and Changed Routing FeaturesWhere
DocumentedIntroduced/Changed in ReleaseDescriptionFeature
Implementing BFD chapter.
BFD over Satellite Interfaces,on page 204
Refer BFD Commands chapterin Cisco IOS XR RoutingCommand
Reference for theCisco CRS Router forinformation on the
commandsused for configuring BFD overSatellite Interface.
Release 4.3.2This feature was introduced.BFD over Satellite
Interface
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Router, Release 4.3.x OL-28410-03 1
-
Where DocumentedIntroduced/Changed in
ReleaseDescriptionFeature
Implementing BGP chapter
BGPVRFDynamicRouteLeaking, on page 65
Configuring VRFDynamic Route Leaking,on page 169
VRF Dynamic RouteLeaking Configuration:Example, on page 181
Refer BGP Commands chapterin Cisco IOS XR RoutingCommand
Reference for theCisco CRS Router forinformation on the
commandsused for configuring VRFDynamic Route Leaking.
Release 4.3.1This feature was introduced.BGP VRF Dynamic
RouteLeaking
Implementing BidirectionalForwarding Detection chapter.
BFD IPv6 Multihop, on page202
ReferBidirectional ForwardingDetection Commands chapterin Cisco
IOS XR RoutingCommand Reference for theCisco CRS Router
forinformation on the commandsused for configuring BFD
IPv6Multihop.
Release 4.3.1This feature was introduced.BFD IPv6 Multihop
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4.3.xNew and Changed Routing Features
-
Where DocumentedIntroduced/Changed in
ReleaseDescriptionFeature
Implementing BidirectionalForwarding Detection chapter.
BFD over MPLS TrafficEngineering LSPs, onpage 203
Enabling BFDParametersfor BFD over TETunnels, on page 233
Configuring BFD Bringup Timeout, on page 234
Configuring BFDDampening for TETunnels, on page 235
Configuring Periodic LSPPing Requests, on page237
Configuring BFD at theTail End, on page 238
Configuring BFD overLSP Sessions on LineCards, on page 239
BFD over MPLS TETunnel Head-endConfiguration: Example,on page
248
BFD over MPLS TETunnel Tail-endConfiguration: Example,on page
248
ReferBidirectional ForwardingDetection Commands chapterin Cisco
IOS XR RoutingCommand Reference for theCisco CRS Router
forinformation on the commandsused for configuring BFD overMPLS
Traffic EngineeringLSPs.
Release 4.3.1This feature was introduced.BFD over MPLS
TrafficEngineering LSPs
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4.3.xNew and Changed Routing Features
-
Where DocumentedIntroduced/Changed in
ReleaseDescriptionFeature
Implementing Routing Policychapter.
VRF Import PolicyEnhancement, on page 569
Refer Routing Policy LanguageCommands chapter inCisco IOS XR
RoutingCommand Reference for theCisco CRS Router forinformation on
the commandsused for configuring VRF RPLBased Import Policy.
Release 4.3.1This feature was introduced.VRF RPL Based Import
Policy
Implementing Routing Policychapter.
Flexible L3VPN LabelAllocationMode, on page570
Label-Mode, on page 529
Refer Routing Policy LanguageCommands chapter inCisco IOS XR
RoutingCommand Reference for theCisco CRS Router forinformation on
the commandsused for configuring FlexibleL3VPN Label
Allocation.
Release 4.3.1This feature was introduced.Flexible L3VPN
LabelAllocation
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4.3.xNew and Changed Routing Features
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Where DocumentedIntroduced/Changed in
ReleaseDescriptionFeature
Implementing RCMD chapter
Route ConvergenceMonitoring andDiagnostics PrefixMonitoring, on
page 601
Enabling RCMDMonitoring for IS-ISPrefixes, on page 601
Enabling RCMDMonitoring for IS-ISPrefixes: Example, onpage
605
Enabling RCMDMonitoring for OSPFPrefixes, on page 603
Enabling RCMDMonitoring for OSPFPrefixes: Example, onpage
605
Refer RCMD Commandschapter in Cisco IOS XRRouting Command
Referencefor the Cisco CRS Router forinformation on the
commandsused for enabling RCMDmonitoring for IS-IS and
OSPFprefixes.
Release 4.3.0This feature was introduced.Route
ConvergenceMonitoringandDiagnostics (RCMD) PrefixMonitoring
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4.3.xNew and Changed Routing Features
-
Where DocumentedIntroduced/Changed in
ReleaseDescriptionFeature
Implementing RCMD chapter
Route ConvergenceMonitoring andDiagnostics OSPF Type3/5/7
Link-stateAdvertisementsMonitoring, on page 601
Enabling RCMDMonitoring for Type 3/5/7OSPF LSAs, on page 604
Enabling RCMDMonitoring for Type 3/5/7OSPF LSAs: Example,on page
606
Refer RCMD Commandschapter in Cisco IOS XRRouting Command
Referencefor the Cisco CRS Router forinformation on the
commandsused for enabling RCMDmonitoring for type 3/5/7
OSPFLSAs.
Release 4.3.0This feature was introduced.Route
ConvergenceMonitoringandDiagnostics (RCMD)OSPFType 3/5/7 LSA
Monitoring
Implementing BGP chapter
Selective VRFDownload, on page 58
Line Card Roles andFilters in Selective VRFDownload, on page
58
Refer BGP Commands chapterin Cisco IOS XR RoutingCommand
Reference for theCisco CRS Router forinformation on the
commandsused for disabling selectiveVRF download (SVD)anddisplaying
SVD role and stateinformation.
Release 4.3.0This feature was introduced.Selective VRF
Download
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Where DocumentedIntroduced/Changed in
ReleaseDescriptionFeature
Implementing BGP chapter
BGP DMZ LinkBandwidth for UnequalCost Recursive LoadBalancing,
on page 61
Enabling BGP UnequalCost Recursive LoadBalancing, on page
161
BGP Unequal CostRecursive LoadBalancing: Example, onpage 179
Refer BGP Commands chapterin Cisco IOS XR RoutingCommand
Reference for theCisco CRS Router forinformation on the
commandsused for enabling BGP unequalcost recursive load
balancing.
Release 4.3.0This feature was introduced.BGP DMZ Link Bandwidth
forUnequal Cost Recursive LoadBalancing
Implementing IS-IS chapter
Unequal Cost MultipathLoad-balancing for IS-IS, onpage 302
Refer IS-IS Commands chapterin Cisco IOS XR RoutingCommand
Reference for theCisco CRS Router forinformation on the
commandsused for enabling unequal costmultipath (UCMP)
calculationfor IS-IS.
Release 4.3.0This feature was introduced.Unequal Cost
MultipathLoad-balancing for IS-IS
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4.3.xNew and Changed Routing Features
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Where DocumentedIntroduced/Changed in
ReleaseDescriptionFeature
Implementing OSPF chapter
VRF-lite Support for OSPFv2,on page 376
ReferOSPFCommands chapterin Cisco IOS XR RoutingCommand
Reference for theCisco CRS Router forinformation on
capabilityvrf-lite command used forconfiguring VRF-lite
capabilityand show ospf command usedto display
VRF-liteconfiguration status.
Release 4.3.0This feature was introduced.OSPFv2 VRF-lite
Implementing OSPF chapter
OSPFv3 Timers Link-stateAdvertisements and ShortestPath First
Throttle DefaultValues Update, on page 377
Refer OSPFv3 Commandschapter in Cisco IOS XRRouting Command
Referencefor the Cisco CRS Routerfortimers throttle lsa all
andtimers throttle spf commandreference information.
Release 4.3.0OSPFv3 Timers LSA and SPFThrottle Commands
DefaultValues were updated.
OSPFv3 Timers Update
Implementing EIGRP chapter
EIGRP Wide MetricComputation, on page 264
Refer EIGRP Commandschapter in Cisco IOS XRRouting Command
Referencefor the Cisco CRS Router forinformation on new andenhanced
commands to supportEIGRP wide metriccomputation.
Release 4.3.0Cisco IOS XR EIGRP wasenhanced to support
widemetric computation.
EIGRP Wide MetricComputation
Implementing and MonitoringRIB chapter
Flex-LSR Label SwitchProcessor 140
Release 4.3.0This feature was introduced.Flex-LSR Label
SwitchProcessor 140
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C H A P T E R 2Implementing BGP
Border Gateway Protocol (BGP) is an Exterior Gateway Protocol
(EGP) that allows you to create loop-freeinterdomain routing
between autonomous systems. An autonomous system is a set of
routers under a singletechnical administration. Routers in an
autonomous system can use multiple Interior Gateway Protocols(IGPs)
to exchange routing information inside the autonomous system and an
EGP to route packets outsidethe autonomous system.
This module provides the conceptual and configuration
information for BGP on Cisco IOS XR software.
For more information about BGP on the Cisco IOS XR software and
complete descriptions of the BGPcommands listed in this module, see
Related Documents, on page 181 section of this module. To
locatedocumentation for other commands that might appear while
performing a configuration task, search onlinein the Cisco IOS XR
software master command index.
Note
Feature History for Implementing BGP
ModificationRelease
This feature was introduced.Release 2.0
No modification.Release 3.0
No modification.Release 3.2
VPN routing and forwarding (VRF) support was added,
includinginformation on VRF command modes and command syntax.
BGP cost community information was added.
Release 3.3.0
The following features were supported:
Four-byte autonomous system (AS) number
Carrier supporting carrier (CSC) for BGP was added. SeeCisco IOS
XR Multiprotocol Label Switching ProtocolConfiguration Guide for
information
Key chains
Release 3.4.0
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ModificationRelease
The following features were supported:
IPv6 Provider Edge and IPv6 VPN Provider Edge overMultiprotocol
Label Switching
Neighbor-specific VRF IPv6 address family configurations
Address family group-specific VPNv6 configurations
VPN4/VPNv6 over IP core using L2TPv3 tunnels
Multicast Distribution Tree (MDT) Subaddress FamilyIdentifier
Information (SAFI) support for multicast VPN(MVPN)
Release 3.5.0
No modification.Release 3.6.0
The following features were supported:
Advertisement of VRF routes for multicast VPNs (MVPN)for both
IPv4 and IPv6 address families from PE to PE
Edits were made to existing MVPN procedures based onnew support
for IPv6 multicast VPNs
Procedure Configuring an MDT Address Family Sessionin BGP, on
page 136 was updated to reflect MVPNconfiguration of MDT SAFI from
PE to PE
Release 3.7.0
The following features were supported:
Border Gateway Protocol (BGP) nonstop routing (NSR)with stateful
switchover (SSO)
Next hop as the IPv6 address of peering interface
Reset weight on import of VPN routes
New commands enforce-first-as andenforce-first-as-disablewere
introduced to provide enableand disable configuration options for
enforce-first-as featurein Neighbor, Neighbor group, and Session
groupconfiguration modes.
Release 3.8.0
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-
ModificationRelease
The following features were supported:
BGP BestExternal Path
BGP Prefix Independent Convergence Unipath PrimaryBackup
BGP Local Label Retention
BGP Over GRE Interfaces
Asplain notation for 4-byte Autonomous System Number
Command Line Interface (CLI) consistency for BGPcommands
L2VPN Address Family Configuration Mode
Release 3.9.0
The following features were supported:
Accumulated iGP (AiGP)
BGP Add Path Advertisement
iBGP Multipath Load Sharing
Next Hop Self on Route Reflector for iBGP+Label
Release 4.0.0
The following features were supported:
BGP RT Constrained Route Distribution
Release 4.1.0
The BGP Accept Own feature was added.Release 4.1.1
The following features were supported:
BGP Multi-Instance/Multi-AS Support
BFD Multihop Support for BGP
BGP Error Handling
Support for Distributed BGP (bgp distributed
speaker)configuration was removed.
Release 4.2.0
The following features were supported:
BGP 3107 PIC Updates for Global Prefixes
BGP Prefix Independent Convergence for RIB and FIB
BGP Prefix Origin Validation Based on RPKI
Release 4.2.1
The BGP Attribute Filtering feature was added.Release 4.2.3
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Implementing BGP
-
ModificationRelease
The BGP DMZ Link Bandwidth for Unequal Cost RecursiveLoad
Balancing feature wad added.
Release 4.3.0
The following features were supported
BGP VRF Dynamic Route Leaking
Release 4.3.1
Prerequisites for Implementing BGP, page 12
Information About Implementing BGP, page 12
How to Implement BGP, page 65
Configuration Examples for Implementing BGP, page 171
Where to Go Next, page 181
Additional References, page 181
Prerequisites for Implementing BGPYou must be in a user group
associated with a task group that includes the proper task IDs. The
commandreference guides include the task IDs required for each
command. If you suspect user group assignment ispreventing you from
using a command, contact your AAA administrator for assistance.
Information About Implementing BGPTo implement BGP, you need to
understand the following concepts:
BGP Functional OverviewBGP uses TCP as its transport protocol.
Two BGP routers form a TCP connection between one another
(peerrouters) and exchange messages to open and confirm the
connection parameters.
BGP routers exchange network reachability information. This
information is mainly an indication of the fullpaths (BGP
autonomous system numbers) that a route should take to reach the
destination network. Thisinformation helps construct a graph that
shows which autonomous systems are loop free and where
routingpolicies can be applied to enforce restrictions on routing
behavior.
Any two routers forming a TCP connection to exchange BGP routing
information are called peers or neighbors.BGP peers initially
exchange their full BGP routing tables. After this exchange,
incremental updates are sentas the routing table changes. BGP keeps
a version number of the BGP table, which is the same for all of
itsBGP peers. The version number changes whenever BGP updates the
table due to routing information changes.Keepalive packets are sent
to ensure that the connection is alive between the BGP peers and
notificationpackets are sent in response to error or special
conditions.
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-
For information on configuring BGP to distribute Multiprotocol
Label Switching (MPLS) Layer 3 virtualprivate network (VPN)
information, see the Cisco IOS XRMultiprotocol Label Switching
ConfigurationGuide for the Cisco CRS-1 Router.
For information on BGP support for Bidirectional Forwarding
Detection (BFD), see the Cisco IOS XRInterface and Hardware
Configuration Guide for the Cisco CRS-1 Router and the Cisco IOS XR
Interfaceand Hardware Command Reference for the Cisco CRS-1
Router.
Note
BGP Router IdentifierFor BGP sessions between neighbors to be
established, BGP must be assigned a router ID. The router ID issent
to BGP peers in the OPEN message when a BGP session is
established.
BGP attempts to obtain a router ID in the following ways (in
order of preference):
By means of the address configured using the bgp router-id
command in router configuration mode.
By using the highest IPv4 address on a loopback interface in the
system if the router is booted with savedloopback address
configuration.
By using the primary IPv4 address of the first loopback address
that gets configured if there are not anyin the saved
configuration.
If none of these methods for obtaining a router ID succeeds, BGP
does not have a router ID and cannot establishany peering sessions
with BGP neighbors. In such an instance, an error message is
entered in the system log,and the show bgp summary command displays
a router ID of 0.0.0.0.
After BGP has obtained a router ID, it continues to use it even
if a better router ID becomes available. Thisusage avoids
unnecessary flapping for all BGP sessions. However, if the router
ID currently in use becomesinvalid (because the interface goes down
or its configuration is changed), BGP selects a new router ID
(usingthe rules described) and all established peering sessions are
reset.
We strongly recommend that the bgp router-id command is
configured to prevent unnecessary changesto the router ID (and
consequent flapping of BGP sessions).
Note
BGP Default LimitsCisco IOS XRBGP imposes maximum limits on the
number of neighbors that can be configured on the routerand on the
maximum number of prefixes that are accepted from a peer for a
given address family. Thislimitation safeguards the router from
resource depletion caused by misconfiguration, either locally or on
theremote neighbor. The following limits apply to BGP
configurations:
The default maximum number of peers that can be configured is
4000. The default can be changed usingthe bgp maximum neighbor
command. The limit range is 1 to 15000. Any attempt to
configureadditional peers beyond the maximum limit or set the
maximum limit to a number that is less than thenumber of peers
currently configured will fail.
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-
To prevent a peer from flooding BGP with advertisements, a limit
is placed on the number of prefixesthat are accepted from a peer
for each supported address family. The default limits can be
overriddenthrough configuration of the maximum-prefix limit command
for the peer for the appropriate addressfamily. The following
default limits are used if the user does not configure the maximum
number ofprefixes for the address family:
IPv4 Unicast: 1048576
IPv4 Multicast: 131072
IPv4 Labeled-unicast: 131072
VPNv4 Unicast: 2097152
IPv4 MDT: 131072
IPv4 Tunnel: 1048576
IPv6 Unicast: 524288
IPv6 Multicast: 131072
IPv6 Labeled-unicast: 131072
VPNv6 Unicast: 1048576
L2VPN EVPN: 2097152
A cease notification message is sent to the neighbor and the
peering with the neighbor is terminatedwhen the number of prefixes
received from the peer for a given address family exceeds the
maximumlimit (either set by default or configured by the user) for
that address family.
It is possible that the maximum number of prefixes for a
neighbor for a given address family has beenconfigured after the
peering with the neighbor has been established and a certain number
of prefixeshave already been received from the neighbor for that
address family. A cease notification message issent to the neighbor
and peering with the neighbor is terminated immediately after the
configuration ifthe configured maximum number of prefixes is fewer
than the number of prefixes that have already beenreceived from the
neighbor for the address family.
BGP Next Hop TrackingBGP receives notifications from the Routing
Information Base (RIB) when next-hop information
changes(event-driven notifications). BGP obtains next-hop
information from the RIB to:
Determine whether a next hop is reachable.
Find the fully recursed IGP metric to the next hop (used in the
best-path calculation).
Validate the received next hops.
Calculate the outgoing next hops.
Verify the reachability and connectedness of neighbors.
BGP is notified when any of the following events occurs:
Next hop becomes unreachable
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-
Next hop becomes reachable
Fully recursed IGP metric to the next hop changes
First hop IP address or first hop interface change
Next hop becomes connected
Next hop becomes unconnected
Next hop becomes a local address
Next hop becomes a nonlocal address
Reachability and recursed metric events trigger a best-path
recalculation.Note
Event notifications from the RIB are classified as critical and
noncritical. Notifications for critical and noncriticalevents are
sent in separate batches. However, a noncritical event is sent
along with the critical events if thenoncritical event is pending
and there is a request to read the critical events.
Critical events are related to the reachability (reachable and
unreachable), connectivity (connected andunconnected), and locality
(local and nonlocal) of the next hops. Notifications for these
events are notdelayed.
Noncritical events include only the IGPmetric changes. These
events are sent at an interval of 3 seconds.A metric change event
is batched and sent 3 seconds after the last one was sent.
The next-hop trigger delay for critical and noncritical events
can be configured to specify a minimum batchinginterval for
critical and noncritical events using the nexthop trigger-delay
command. The trigger delay isaddress family dependent.
The BGP next-hop tracking feature allows you to specify that BGP
routes are resolved using only next hopswhose routes have the
following characteristics:
To avoid the aggregate routes, the prefix length must be greater
than a specified value.
The source protocol must be from a selected list, ensuring that
BGP routes are not used to resolve nexthops that could lead to
oscillation.
This route policy filtering is possible because RIB identifies
the source protocol of route that resolved a nexthop as well as the
mask length associated with the route. The nexthop route-policy
command is used tospecify the route-policy.
For information on route policy filtering for next hops using
the next-hop attach point, see the ImplementingRouting Policy
Language on Cisco IOS XR Software module of Cisco IOS XR Routing
ConfigurationGuide (this publication).
Next Hop as the IPv6 Address of Peering InterfaceBGP can carry
IPv6 prefixes over an IPv4 session. The next hop for the IPv6
prefixes can be set through anexthop policy. In the event that the
policy is not configured, the nexthops are set as the IPv6 address
of thepeering interface (IPv6 neighbor interface or IPv6 update
source interface, if any one of the interfaces isconfigured).
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If the nexthop policy is not configured and neither the IPv6
neighbor interface nor the IPv6 update sourceinterface is
configured, the next hop is the IPv4 mapped IPv6 address.
Scoped IPv4/VPNv4 Table WalkTo determine which address family to
process, a next-hop notification is received by first dereferencing
thegateway context associated with the next hop, then looking into
the gateway context to determine whichaddress families are using
the gateway context. The IPv4 unicast and VPNv4 unicast address
families sharethe same gateway context, because they are registered
with the IPv4 unicast table in the RIB. As a result, boththe global
IPv4 unicast table and the VPNv4 table are processed when an IPv4
unicast next-hop notificationis received from the RIB. A mask is
maintained in the next hop, indicating whether the next hop belongs
toIPv4 unicast or VPNv4 unicast, or both. This scoped table walk
localizes the processing in the appropriateaddress family
table.
Reordered Address Family ProcessingThe Cisco IOS XR software
walks address family tables based on the numeric value of the
address family.When a next-hop notification batch is received, the
order of address family processing is reordered to thefollowing
order:
IPv4 tunnel
VPNv4 unicast
VPNv6 unicast
IPv4 labeled unicast
IPv4 unicast
IPv4 MDT
IPv4 multicast
IPv6 unicast
IPv6 multicast
IPv6 labeled unicast
New Thread for Next-Hop ProcessingThe critical-event thread in
the spkr process handles only next-hop, Bidirectional Forwarding
Detection (BFD),and fast-external-failover (FEF) notifications.
This critical-event thread ensures that BGP convergence is
notadversely impacted by other events that may take a significant
amount of time.
show, clear, and debug CommandsThe show bgp nexthops command
provides statistical information about next-hop notifications, the
amountof time spent in processing those notifications, and details
about each next hop registered with the RIB. Theclear bgp nexthop
performance-statistics command ensures that the cumulative
statistics associated withthe processing part of the next-hop show
command can be cleared to help in monitoring. The clear bgpnexthop
registration command performs an asynchronous registration of the
next hop with the RIB. See the
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BGP Commands on Cisco IOS XR Software module of Cisco IOS XR
Routing Command Reference for theCisco CRS Routerfor information on
the next-hop show and clear commands.
The debug bgp nexthop command displays information on next-hop
processing. The out keyword providesdebug information only about
BGP registration of next hops with RIB. The in keyword displays
debuginformation about next-hop notifications received from RIB.
The out keyword displays debug informationabout next-hop
notifications sent to the RIB. See the BGP Debug Commands on Cisco
IOS XR Softwaremodule of Cisco IOS XR Routing Debug Command
Reference for the Cisco CRS-1 Router .
Autonomous System Number Formats in BGPAutonomous system numbers
(ASNs) are globally unique identifiers used to identify autonomous
systems(ASs) and enable ASs to exchange exterior routing
information between neighboring ASs. A unique ASN isallocated to
each AS for use in BGP routing. ASNs are encoded as 2-byte numbers
and 4-byte numbers inBGP.
2-byte Autonomous System Number FormatThe 2-byte ASNs are
represented in asplain notation. The 2-byte range is 1 to
65535.
4-byte Autonomous System Number FormatTo prepare for the
eventual exhaustion of 2-byte Autonomous SystemNumbers (ASNs), BGP
has the capabilityto support 4-byte ASNs. The 4-byte ASNs are
represented both in asplain and asdot notations.
The byte range for 4-byte ASNs in asplain notation is
1-4294967295. The AS is represented as a 4-bytedecimal number. The
4-byte ASN asplain representation is defined in
draft-ietf-idr-as-representation-01.txt.
For 4-byte ASNs in asdot format, the 4-byte range is 1.0 to
65535.65535 and the format is:
high-order-16-bit-value-in-decimal .
low-order-16-bit-value-in-decimal
The BGP 4-byte ASN capability is used to propagate 4-byte-based
AS path information across BGP speakersthat do not support 4-byte
AS numbers. See draft-ietf-idr-as4bytes-12.txt for information on
increasing thesize of an ASN from 2 bytes to 4 bytes. AS is
represented as a 4-byte decimal number
as-format CommandThe as-format command configures the ASN
notation to asdot. The default value, if the as-format commandis
not configured, is asplain.
BGP ConfigurationBGP in Cisco IOS XR software follows a
neighbor-based configuration model that requires that
allconfigurations for a particular neighbor be grouped in one place
under the neighbor configuration. Peer groupsare not supported for
either sharing configuration between neighbors or for sharing
update messages. Theconcept of peer group has been replaced by a
set of configuration groups to be used as templates in
BGPconfiguration and automatically generated update groups to share
update messages between neighbors.
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Configuration ModesBGP configurations are grouped into modes.
The following sections show how to enter some of the
BGPconfiguration modes. From a mode, you can enter the ? command to
display the commands available in thatmode.
Router Configuration Mode
The following example shows how to enter router configuration
mode:
RP/0/RP0/CPU0:router# configurationRP/0/RP0/CPU0:router(config)#
router bgp 140RP/0/RP0/CPU0:router(config-bgp)#
Router Address Family Configuration Mode
The following example shows how to enter router address family
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
112RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4
multicastRP/0/RP0/CPU0:router(config-bgp-af)#
Neighbor Configuration Mode
The following example shows how to enter neighbor configuration
mode:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# neighbor
10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)#
Neighbor Address Family Configuration Mode
The following example shows how to enter neighbor address family
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
112RP/0/RP0/CPU0:router(config-bgp)# neighbor
10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4
unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)#
VRF Configuration Mode
The following example shows how to enter VPN routing and
forwarding (VRF) configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# vrf
vrf_ARP/0/RP0/CPU0:router(config-bgp-vrf)#
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VRF Address Family Configuration Mode
The following example shows how to enter VRF address family
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
112RP/0/RP0/CPU0:router(config-bgp)# vrf
vrf_ARP/0/RP0/CPU0:router(config-bgp-vrf)# address-family ipv4
unicastRP/0/RP0/CPU0:router(config-bgp-vrf-af)#
VRF Neighbor Configuration Mode
The following example shows how to enter VRF neighbor
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# vrf
vrf_ARP/0/RP0/CPU0:router(config-bgp-vrf)# neighbor
11.0.1.2RP/0/RP0/CPU0:router(config-bgp-vrf-nbr)#
VRF Neighbor Address Family Configuration Mode
The following example shows how to enter VRF neighbor address
family configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
112RP/0/RP0/CPU0:router(config-bgp)# vrf
vrf_ARP/0/RP0/CPU0:router(config-bgp-vrf)# neighbor
11.0.1.2RP/0/RP0/CPU0:router(config-bgp-vrf-nbr)# address-family
ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-vrf-nbr-af)#
VPNv4 Address Family Configuration Mode
The following example shows how to enter VPNv4 address family
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
152RP/0/RP0/CPU0:router(config-bgp)# address-family vpnv4
unicastRP/0/RP0/CPU0:router(config-bgp-af)#
VPNv6 Address Family Configuration Mode
The following example shows how to enter VPNv6 address family
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
150RP/0/RP0/CPU0:router(config-bgp)# address-family vpnv6
unicastRP/0/RP0/CPU0:router(config-bgp-af)#
L2VPN Address Family Configuration Mode
The following example shows how to enter L2VPN address family
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
100RP/0/RP0/CPU0:router(config-bgp)# address-family l2vpn
vpls-vpws
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RP/0/RP0/CPU0:router(config-bgp-af)#
Neighbor Submode Cisco IOS XR BGP uses a neighbor submode to
make it possible to enter configurations without having toprefix
every configuration with the neighbor keyword and the neighbor
address:
Cisco IOS XR software has a submode available for neighbors in
which it is not necessary for everycommand to have a neighbor
x.x.x.x prefix:
In Cisco IOS XR software, the configuration is as follows:
RP/0/RP0/CPU0:router(config-bgp)# neighbor
192.23.1.2RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as
2002RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4
multicast
An address family configuration submode inside the neighbor
configuration submode is available forentering address
family-specific neighbor configurations. In Cisco IOS XR software,
the configurationis as follows:
RP/0/RP0/CPU0:router(config-bgp)# neighbor
2002::2RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as
2023RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv6
unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)#
next-hop-selfRP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policy
one in
You must enter neighbor-specific IPv4, IPv6, VPNv4, or VPNv6
commands in neighbor address-familyconfiguration submode. In Cisco
IOS XR software, the configuration is as follows:
RP/0/RP0/CPU0:router(config)# router bgp
109RP/0/RP0/CPU0:router(config-bgp)# neighbor
192.168.40.24RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as
1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4
unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# maximum-prefix
1000
Youmust enter neighbor-specific IPv4 and IPv6 commands in VRF
neighbor address-family configurationsubmode. In Cisco IOS XR
software, the configuration is as follows:
RP/0/RP0/CPU0:router(config)# router bgp
110RP/0/RP0/CPU0:router(config-bgp)# vrf
vrf_ARP/0/RP0/CPU0:router(config-bgp-vrf)# neighbor
11.0.1.2RP/0/RP0/CPU0:router(config-bgp-vrf-nbr)# address-family
ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-vrf-nbr-af)#
route-policy pass all in
Configuration TemplatesThe af-group, session-group, and
neighbor-group configuration commands provide template support
forthe neighbor configuration in Cisco IOS XR software.
The af-group command is used to group address family-specific
neighbor commands within an IPv4, IPv6,VPNv4, or VPNv6 address
family. Neighbors that have the same address family configuration
are able to usethe address family group (af-group) name for their
address family-specific configuration. A neighbor inheritsthe
configuration from an address family group by way of the use
command. If a neighbor is configured touse an address family group,
the neighbor (by default) inherits the entire configuration from
the address family
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group. However, a neighbor does not inherit all of the
configuration from the address family group if itemsare explicitly
configured for the neighbor. The address family group configuration
is entered under the BGProuter configuration mode. The following
example shows how to enter address family group configurationmode
:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# af-group afmcast1
address-family ipv4
multicastRP/0/RP0/CPU0:router(config-bgp-afgrp)#
The session-group command allows you to create a session group
from which neighbors can inherit addressfamily-independent
configuration. A neighbor inherits the configuration from a session
group by way of theuse command. If a neighbor is configured to use
a session group, the neighbor (by default) inherits the
entireconfiguration of the session group. A neighbor does not
inherit all of the configuration from a session groupif a
configuration is done directly on that neighbor. The following
example shows how to enter session groupconfiguration mode:
RP/0/RP0/CPU0:router# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# session-group
session1RP/0/RP0/CPU0:router(config-bgp-sngrp)#
The neighbor-group command helps you apply the same
configuration to one or more neighbors. Neighborgroups can include
session groups and address family groups and can comprise the
complete configurationfor a neighbor. After a neighbor group is
configured, a neighbor can inherit the configuration of the
groupusing the use command. If a neighbor is configured to use a
neighbor group, the neighbor inherits the entireBGP configuration
of the neighbor group.
The following example shows how to enter neighbor group
configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
123RP/0/RP0/CPU0:router(config-bgp)# neighbor-group
nbrgroup1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
The following example shows how to enter neighbor group address
family configuration mode:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# neighbor-group
nbrgroup1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family
ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)#
However, a neighbor does not inherit all of the configuration
from the neighbor group if items areexplicitly configured for the
neighbor. In addition, some part of the configuration of the
neighbor groupcould be hidden if a session group or address family
group was also being used.
Configuration grouping has the following effects in Cisco IOS XR
software:
Commands entered at the session group level define address
family-independent commands (the samecommands as in the neighbor
submode).
Commands entered at the address family group level define
address family-dependent commands for aspecified address family
(the same commands as in the neighbor-address family configuration
submode).
Commands entered at the neighbor group level define address
family-independent commands and addressfamily-dependent commands
for each address family (the same as all available neighbor
commands),and define the use command for the address family group
and session group commands.
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Template Inheritance RulesIn Cisco IOS XR software, BGP
neighbors or groups inherit configuration from other configuration
groups.
For address family-independent configurations:
Neighbors can inherit from session groups and neighbor
groups.
Neighbor groups can inherit from session groups and other
neighbor groups.
Session groups can inherit from other session groups.
If a neighbor uses a session group and a neighbor group, the
configurations in the session group arepreferred over the global
address family configurations in the neighbor group.
For address family-dependent configurations:
Address family groups can inherit from other address family
groups.
Neighbor groups can inherit from address family groups and other
neighbor groups.
Neighbors can inherit from address family groups and neighbor
groups.
Configuration group inheritance rules are numbered in order of
precedence as follows:
1 If the item is configured directly on the neighbor, that value
is used. In the example that follows, theadvertisement interval is
configured both on the neighbor group and neighbor configuration
and theadvertisement interval being used is from the neighbor
configuration:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# neighbor-group
AS_1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval
15RP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor
10.1.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as
1RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group
AS_1RP/0/RP0/CPU0:router(config-bgp-nbr)# advertisement-interval
20
The following output from the show bgp neighbors command shows
that the advertisement interval usedis 20 seconds:
RP/0/RP0/CPU0:router# show bgp neighbors 10.1.1.1
BGP neighbor is 10.1.1.1, remote AS 1, local AS 140, external
linkRemote router ID 0.0.0.0BGP state = IdleLast read 00:00:00,
hold time is 180, keepalive interval is 60 secondsReceived 0
messages, 0 notifications, 0 in queueSent 0 messages, 0
notifications, 0 in queueMinimum time between advertisement runs is
20 seconds
For Address Family: IPv4 UnicastBGP neighbor version 0Update
group: 0.1eBGP neighbor with no inbound or outbound policy;
defaults to 'drop'Route refresh request: received 0, sent 00
accepted prefixesPrefix advertised 0, suppressed 0, withdrawn 0,
maximum limit 524288Threshold for warning message 75%
Connections established 0; dropped 0Last reset 00:00:14, due to
BGP neighbor initializedExternal BGP neighbor not directly
connected.
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2 Otherwise, if an item is configured to be inherited from a
session-group or neighbor-group and on theneighbor directly, then
the configuration on the neighbor is used. If a neighbor is
configured to be inheritedfrom session-group or af-group, but no
directly configured value, then the value in the session-group
oraf-group is used. In the example that follows, the advertisement
interval is configured on a neighbor groupand a session group and
the advertisement interval value being used is from the session
group:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# session-group
AS_2RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval
15RP/0/RP0/CPU0:router(config-bgp-sngrp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor-group
AS_1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval
20RP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor
192.168.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as
1RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group
AS_2RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group
AS_1
The following output from the show bgp neighbors command shows
that the advertisement interval usedis 15 seconds:
RP/0/RP0/CPU0:router# show bgp neighbors 192.168.0.1
BGP neighbor is 192.168.0.1, remote AS 1, local AS 140, external
linkRemote router ID 0.0.0.0BGP state = IdleLast read 00:00:00,
hold time is 180, keepalive interval is 60 secondsReceived 0
messages, 0 notifications, 0 in queueSent 0 messages, 0
notifications, 0 in queueMinimum time between advertisement runs is
15 seconds
For Address Family: IPv4 UnicastBGP neighbor version 0Update
group: 0.1eBGP neighbor with no inbound or outbound policy;
defaults to 'drop'Route refresh request: received 0, sent 00
accepted prefixesPrefix advertised 0, suppressed 0, withdrawn 0,
maximum limit 524288Threshold for warning message 75%
Connections established 0; dropped 0Last reset 00:03:23, due to
BGP neighbor initializedExternal BGP neighbor not directly
connected.
3 Otherwise, if the neighbor uses a neighbor group and does not
use a session group or address family group,the configuration value
can be obtained from the neighbor group either directly or through
inheritance. Inthe example that follows, the advertisement interval
from the neighbor group is used because it is notconfigured
directly on the neighbor and no session group is used:
RP/0/RP0/CPU0:router(config)# router bgp
150RP/0/RP0/CPU0:router(config-bgp)# session-group
AS_2RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval
20RP/0/RP0/CPU0:router(config-bgp-sngrp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor-group
AS_1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval
15RP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor
192.168.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as
1RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group AS_1
The following output from the show bgp neighbors command shows
that the advertisement interval usedis 15 seconds:
RP/0/RP0/CPU0:router# show bgp neighbors 192.168.1.1
BGP neighbor is 192.168.2.2, remote AS 1, local AS 140, external
link
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Remote router ID 0.0.0.0BGP state = IdleLast read 00:00:00, hold
time is 180, keepalive interval is 60 secondsReceived 0 messages, 0
notifications, 0 in queueSent 0 messages, 0 notifications, 0 in
queueMinimum time between advertisement runs is 15 seconds
For Address Family: IPv4 UnicastBGP neighbor version 0Update
group: 0.1eBGP neighbor with no outbound policy; defaults to
'drop'Route refresh request: received 0, sent 0Inbound path policy
configuredPolicy for incoming advertisements is POLICY_10 accepted
prefixesPrefix advertised 0, suppressed 0, withdrawn 0, maximum
limit 524288Threshold for warning message 75%
Connections established 0; dropped 0Last reset 00:01:14, due to
BGP neighbor initializedExternal BGP neighbor not directly
connected.
To illustrate the same rule, the following example shows how to
set the advertisement interval to 15 (fromthe session group) and 25
(from the neighbor group). The advertisement interval set in the
session groupoverrides the one set in the neighbor group. The
inbound policy is set to POLICY_1 from the neighborgroup.
RP/0/RP0/CPU0:routerconfig)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# session-group
ADVRP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval
15RP/0/RP0/CPU0:router(config-bgp-sngrp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor-group
ADV_2RP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
advertisement-interval 25RP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
address-family ipv4
unicastRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# route-policy
POLICY_1 inRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)#
exitRP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
exitRP/0/RP0/CPU0:router(config-bgp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor
192.168.2.2RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as
1RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group
ADVRP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group
ADV_2
The following output from the show bgp neighbors command shows
that the advertisement interval usedis 15 seconds:
RP/0/RP0/CPU0:router# show bgp neighbors 192.168.2.2
BGP neighbor is 192.168.2.2, remote AS 1, local AS 140, external
linkRemote router ID 0.0.0.0BGP state = IdleLast read 00:00:00,
hold time is 180, keepalive interval is 60 secondsReceived 0
messages, 0 notifications, 0 in queueSent 0 messages, 0
notifications, 0 in queueMinimum time between advertisement runs is
15 seconds
For Address Family: IPv4 UnicastBGP neighbor version 0Update
group: 0.1eBGP neighbor with no inbound or outbound policy;
defaults to 'drop'Route refresh request: received 0, sent 00
accepted prefixesPrefix advertised 0, suppressed 0, withdrawn 0,
maximum limit 524288Threshold for warning message 75%
Connections established 0; dropped 0Last reset 00:02:03, due to
BGP neighbor initializedExternal BGP neighbor not directly
connected.
Cisco IOS XR Routing Configuration Guide for the Cisco CRS
Router, Release 4.3.x24 OL-28410-03
Implementing BGPBGP Configuration
-
4 Otherwise, the default value is used. In the example that
follows, neighbor 10.0.101.5 has the minimumtime between
advertisement runs set to 30 seconds (default) because the neighbor
is not configured to usethe neighbor configuration or the neighbor
group configuration:
RP/0/RP0/CPU0:router(config)# router bgp
140RP/0/RP0/CPU0:router(config-bgp)# neighbor-group
AS_1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as
1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)#
exitRP/0/RP0/CPU0:router(config-bgp)# neighbor-group
adv_15RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remo