Cisco ASR 9000 Series User manual

Cisco ASR 9000 Series Aggregation Services Router Routing
Configuration Guide, Release 5.1.x
First Published: 2013-09-01
Last Modified: 2014-04-01
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Text Part Number: OL-30423-03

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CONTENTS
Preface Preface xxvii
Obtaining Documentation and Submitting a Service Request xxvii
CHAPTER 1 New and Changed Routing Features 1
New and Changed Routing Features 1
CHAPTER 2 Implementing BGP 7
Prerequisites for Implementing BGP 9
Information About Implementing BGP 9
BGP Functional Overview 10
BGP Router Identifier 10
BGP Default Limits 11
BGP Next Hop Tracking 12
Scoped IPv4/VPNv4 Table Walk 13
Reordered Address Family Processing 13
New Thread for Next-Hop Processing 13
show, clear, and debug Commands 13
Autonomous System Number Formats in BGP 14
2-byte Autonomous System Number Format 14
4-byte Autonomous System Number Format 14
as-format Command 14
BGP Configuration 14
Configuration Modes 15
Router Configuration Mode 15
Router Address Family Configuration Mode 15
Neighbor Configuration Mode 15
Neighbor Address Family Configuration Mode 15
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VRF Configuration Mode 15
VRF Address Family Configuration Mode 16
Configuring Resilient Per-CE Label Allocation Mode Under VRF Address
Family 16
Configuring Resilient Per-CE Label Allocation Mode Using a
Route-Policy 18
VRF Neighbor Configuration Mode 19
VRF Neighbor Address Family Configuration Mode 19
VPNv4 Address Family Configuration Mode 19
L2VPN Address Family Configuration Mode 20
Neighbor Submode 20
Configuration Templates 21
Template Inheritance Rules 22
Viewing Inherited Configurations 25
show bgp neighbors 26
show bgp af-group 27
show bgp session-group 28
show bgp neighbor-group 29
No Default Address Family 30
Neighbor Address Family Combinations 30
Routing Policy Enforcement 31
Table Policy 32
Update Groups 33
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 34
Cost Community Support for Aggregate Routes and Multipaths 35
Influencing Route Preference in a Multiexit IGP Network 36
BGP Cost Community Support for EIGRP MPLS VPN PE-CE with Back-door
Links 37
Adding Routes to the Routing Information Base 38
BGP Best Path Algorithm 38
Comparing Pairs of Paths 39
Order of Comparisons 40
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Best Path Change Suppression 41
Administrative Distance 42
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 Local Label Retention 52
Command Line Interface (CLI) Consistency for BGP Commands 53
BGP Additional Paths 53
iBGP Multipath Load Sharing 53
BGP Selective Multipath 54
Accumulated Interior Gateway Protocol Attribute 56
Per VRF and Per CE Label for IPv6 Provider Edge 56
IPv4 BGP-Policy Accounting on Cisco ASR 9000's A9K-SIP-700 56
IPv6 Unicast Routing on Cisco ASR 9000's A9K-SIP-700 57
IPv6 uRPF Support on Cisco ASR 9000's A9K-SIP-700 57
Remove and Replace Private AS Numbers from AS Path in BGP 57
Selective VRF Download 58
Line Card Roles and Filters in Selective VRF Download 58
Selective VRF Download Disable 59
Calculating Routes Downloaded to Line Card with or without SVD 59
BGP Accept Own 61
BGP DMZ Link Bandwidth for Unequal Cost Recursive Load Balancing 63
BFD Multihop Support for BGP 63
BGP Multi-Instance and Multi-AS 63
BGP Prefix Origin Validation Based on RPKI 64
Configuring RPKI Cache-server 64
Configuring RPKI Prefix Validation 67
Configuring RPKI Bestpath Computation 68
BGP 3107 PIC Updates for Global Prefixes 69
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BGP Prefix Independent Convergence for RIB and FIB 70
BGP Update Message Error Handling 71
BGP Attribute Filtering 71
BGP Attribute Filter Actions 71
BGP Error Handling and Attribute Filtering Syslog Messages 72
BGP Link-State 72
BGP Permanent Network 73
BGP-RIB Feedback Mechanism for Update Generation 73
BGP VRF Dynamic Route Leaking 74
User Defined Martian Check 74
Resilient Per-CE Label Allocation Mode 75
How to Implement BGP 75
Enabling BGP Routing 75
Configuring Multiple BGP Instances for a Specific Autonomous System 78
Configuring a Routing Domain Confederation for BGP 78
Resetting an eBGP Session Immediately Upon Link Failure 79
Logging Neighbor Changes 80
Adjusting BGP Timers 80
Changing the BGP Default Local Preference Value 81
Configuring the MED Metric for BGP 82
Configuring BGP Weights 83
Tuning the BGP Best-Path Calculation 84
Indicating BGP Back-door Routes 85
Configuring Aggregate Addresses 86
Redistributing iBGP Routes into IGP 87
Redistributing Prefixes into Multiprotocol BGP 88
Configuring BGP Route Dampening 90
Applying Policy When Updating the Routing Table 95
Setting BGP Administrative Distance 96
Configuring a BGP Neighbor Group and Neighbors 96
Configuring a Route Reflector for BGP 99
Configuring BGP Route Filtering by Route Policy 100
Configuring BGP Attribute Filtering 102
Configuring BGP Next-Hop Trigger Delay 103
Disabling Next-Hop Processing on BGP Updates 104
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Configuring BGP Community and Extended-Community Advertisements 105
Configuring the BGP Cost Community 107
Configuring Software to Store Updates from a Neighbor 110
Configuring a VPN Routing and Forwarding Instance in BGP 112
Defining Virtual Routing and Forwarding Tables in Provider Edge Routers 112
Configuring the Route Distinguisher 114
Configuring PE-PE or PE-RR Interior BGP Sessions 115
Configuring Route Reflector to Hold Routes That Have a Defined Set of RT
Communities 118
Configuring BGP as a PE-CE Protocol 119
Redistribution of IGPs to BGP 123
Configuring Keychains for BGP 125
Disabling a BGP Neighbor 126
Resetting Neighbors Using BGP Inbound Soft Reset 127
Resetting Neighbors Using BGP Outbound Soft Reset 128
Resetting Neighbors Using BGP Hard Reset 129
Clearing Caches, Tables, and Databases 130
Displaying System and Network Statistics 131
Displaying BGP Process Information 132
Monitoring BGP Update Groups 134
Configuring BGP Nonstop Routing 135
Installing Primary Backup Path for Prefix Independent Convergence (PIC) 136
Retaining Allocated Local Label for Primary Path 137
Configuring BGP Additional Paths 138
Configuring iBGP Multipath Load Sharing 139
Originating Prefixes with AiGP 140
Configuring BGP Accept Own 142
Configuring BGP Link-State 143
Configuring BGP Link-state 143
Configuring Domain Distinguisher 144
Configuring BGP Permanent Network 145
Configuring BGP Permanent Network 145
How to Advertise Permanent Network 147
Enabling BGP Unequal Cost Recursive Load Balancing 148
Configuring VRF Dynamic Route Leaking 150
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Enabling Selective VRF Download 152
Disabling Selective VRF Download 154
Configuring Resilient Per-CE Label Allocation Mode 155
Configuring Resilient Per-CE Label Allocation Mode Under VRF Address Family 155
Configuring Resilient Per-CE Label Allocation Mode Using a Route-Policy 157
Configuration Examples for Implementing BGP 159
Enabling BGP: Example 159
Displaying BGP Update Groups: Example 160
BGP Neighbor Configuration: Example 161
BGP Confederation: Example 161
BGP Route Reflector: Example 163
BGP Nonstop Routing Configuration: Example 163
Primary Backup Path Installation: Example 164
Allocated Local Label Retention: Example 164
iBGP Multipath Loadsharing Configuration: Example 164
Originating Prefixes With AiGP: Example 164
BGP Accept Own Configuration: Example 165
BGP Unequal Cost Recursive Load Balancing: Example 165
VRF Dynamic Route Leaking Configuration: Example 167
Resilient Per-CE Label Allocation Mode Configuration: Example 168
Configuring Resilient Per-CE Label Allocation Mode Under VRF Address Family:
Example 168
Configuring Resilient Per-CE Label Allocation Mode Using a Route-Policy:
Example 168
Where to Go Next 168
Additional References 168
CHAPTER 3 Implementing BFD 173
Prerequisites for Implementing BFD 175
Restrictions for Implementing BFD 176
Information About BFD 177
Differences in BFD in Cisco IOS XR Software and Cisco IOS Software 177
BFD Multipath Sessions Support on nV Edge System 178
BFD Modes of Operation 178
BFD Packet Information 179
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BFD Source and Destination Ports 179
BFD Packet Intervals and Failure Detection 179
BFD Packet Intervals on Physical Interfaces 179
BFD Packet Intervals on Bundle Member Links 180
Control Packet Failure Detection In Asynchronous Mode 180
Echo Packet Failure Detection In Asynchronous Mode 180
Echo Failure Detection Examples 181
Summary of Packet Intervals and Failure Detection Times for BFD on Bundle
Interfaces 182
Echo Packet Latency 183
Priority Settings for BFD Packets 183
BFD for IPv4 184
Enabling BFD on a Static Route 185
BFD for IPv6 187
BFD on Bundled VLANs 187
BFD Over Member Links on Link Bundles 188
Overview of BFD State Change Behavior on Member Links and Bundle Status 188
BFD Multipath Sessions 190
BFD for MultiHop Paths 190
Setting up BFD Multihop 191
BFD over MPLS Traffic Engineering LSPs 191
Bidirectional Forwarding Detection over Logical Bundle 191
Bidirectional Forwarding Detection over Generic Routing Encapsulation 192
Bidirectional Forwarding Detection IPv6 Multihop 192
BFD over Pseudowire Headend 193
BFD over Satellite Interfaces 193
BFD over IRB 193
BFD over Bundle Per-Member Link 194
BFD Dampening 195
BFD Hardware Offload 195
BFD Object Tracking 196
How to Configure BFD 196
BFD Configuration Guidelines 196
Configuring BFD Under a Dynamic Routing Protocol or Using a Static Route 197
Enabling BFD on a BGP Neighbor 197
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Enabling BFD for OSPF on an Interface 199
Enabling BFD for OSPFv3 on an Interface 200
Enabling BFD on a Static Route 202
Configuring BFD on Bundle Member Links 204
Prerequisites for Configuring BFD on Bundle Menmber Links 204
Specifying the BFD Destination Address on a Bundle 204
Enabling BFD Sessions on Bundle Members 204
Configuring the Minimum Thresholds for Maintaining an Active Bundle 205
Configuring BFD Packet Transmission Intervals and Failure Detection Times on a
Bundle 206
Configuring Allowable Delays for BFD State Change Notifications Using Timers on
a Bundle 208
Enabling Echo Mode to Test the Forwarding Path to a BFD Peer 209
Overriding the Default Echo Packet Source Address 209
Specifying the Echo Packet Source Address Globally for BFD 209
Specifying the Echo Packet Source Address on an Individual Interface or Bundle 210
Configuring BFD Session Teardown Based on Echo Latency Detection 211
Delaying BFD Session Startup Until Verification of Echo Path and Latency 212
Disabling Echo Mode 213
Disabling Echo Mode on a Router 213
Disabling Echo Mode on an Individual Interface or Bundle 214
Minimizing BFD Session Flapping Using BFD Dampening 215
Enabling and Disabling IPv6 Checksum Support 216
Enabling and Disabling IPv6 Checksum Calculations for BFD on a Router 216
Enabling and Disabling IPv6 Checksum Calculations for BFD on an Individual Interface
or Bundle 217
Clearing and Displaying BFD Counters 218
Configuring Coexistence Between BFD over Bundle (BoB) and BFD over Logical Bundle
(BLB) 219
Configuring BFD IPv6 Multihop 220
Configuring BFD IPv6 Multihop for eBGP Neighbors 220
Configuring BFD IPv6 Multihop for iBGP Neighbors 221
Configuring BFD over MPLS Traffic Engineering LSPs 222
Enabling BFD Parameters for BFD over TE Tunnels 222
Configuring BFD Bring up Timeout 223
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