Cisco NCS 6000 Series User manual

Routing Configuration Guide for Cisco NCS 6000 Series Routers, IOS
XR Release 6.4.x
First Published: 2018-03-01
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CONTENTS
Preface xxi
PREFACE
Changes to This Document xxi
Obtaining Documentation and Submitting a Service Request xxi
New and Changed Routing Features 1
CHAPTER 1
New and Changed Routing Features 1
Implementing BGP 3
CHAPTER 2
Prerequisites for Implementing BGP 3
Information About Implementing BGP 4
BGP Functional Overview 4
BGP Router Identifier 4
BGP Default Limits 5
BGP Next Hop Tracking 5
Next Hop as the IPv6 Address of Peering Interface 6
Scoped IPv4 Table Walk 7
Reordered Address Family Processing 7
New Thread for Next-Hop Processing 7
show, clear, and debug Commands 7
Autonomous System Number Formats in BGP 7
2-byte Autonomous System Number Format 8
4-byte Autonomous System Number Format 8
as-format Command 8
BGP Configuration 8
Configuration Modes 8
Neighbor Submode 9
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Configuration Templates 9
Template Inheritance Rules 11
Viewing Inherited Configurations 15
No Default Address Family 19
Neighbor Address Family Combinations 19
Routing Policy Enforcement 20
Table Policy 21
Update Groups 21
BGP Update Generation and Update Groups 21
BGP Update Group 21
BGP Cost Community 22
How BGP Cost Community Influences the Best Path Selection Process 22
Cost Community Support for Aggregate Routes and Multipaths 23
Influencing Route Preference in a Multiexit IGP Network 24
Adding Routes to the Routing Information Base 25
BGP Best Path Algorithm 25
Comparing Pairs of Paths 26
Order of Comparisons 28
Best Path Change Suppression 28
Administrative Distance 29
Route Dampening 30
Minimizing Flapping 31
BGP Routing Domain Confederation 31
BGP Route Reflectors 31
Remotely Triggered Blackhole Filtering with RPL Next-hop Discard Configuration 34
Configuring Destination-based RTBH Filtering 34
Verification 36
Default Address Family for show Commands 37
BGP Keychains 37
BGP Nonstop Routing 37
BGP Best-External Path 39
BGP Local Label Retention 40
BGP Over GRE Interfaces 40
Command Line Interface (CLI) Consistency for BGP Commands 40
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BGP Additional Paths 40
BGP Selective Multipath 41
Accumulated Interior Gateway Protocol Attribute 42
BFD Multihop Support for BGP 43
BGP Multi-Instance and Multi-AS 43
BGP Prefix Independent Convergence for RIB and FIB 44
BGP Update Message Error Handling 44
BGP Attribute Filtering 44
BGP Attribute Filter Actions 45
BGP VRF Dynamic Route Leaking 45
How to Implement BGP 46
Enabling BGP Routing 46
Configuring Multiple BGP Instances for a Specific Autonomous System 48
Configuring a Routing Domain Confederation for BGP 49
Resetting an eBGP Session Immediately Upon Link Failure 50
Logging Neighbor Changes 50
Adjusting BGP Timers 51
Changing the BGP Default Local Preference Value 52
Configuring the MED Metric for BGP 52
Configuring BGP Weights 53
Tuning the BGP Best-Path Calculation 54
Indicating BGP Back-door Routes 55
Configuring Aggregate Addresses 56
Redistributing iBGP Routes into IGP 57
Redistributing Prefixes into Multiprotocol BGP 58
Configuring BGP Route Dampening 60
Applying Policy When Updating the Routing Table 60
Setting BGP Administrative Distance 61
Configuring a BGP Neighbor Group and Neighbors 62
Configuring a Route Reflector for BGP 64
Configuring BGP Route Filtering by Route Policy 66
Configuring BGP Attribute Filtering 67
Configuring BGP Next-Hop Trigger Delay 68
Disabling Next-Hop Processing on BGP Updates 69
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Configuring BGP Community and Extended-Community Advertisements 70
Configuring the BGP Cost Community 72
Configuring Software to Store Updates from a Neighbor 74
Configuring Keychains for BGP 76
Disabling a BGP Neighbor 77
Resetting Neighbors Using BGP Inbound Soft Reset 77
Resetting Neighbors Using BGP Outbound Soft Reset 78
Resetting Neighbors Using BGP Hard Reset 79
Clearing Caches, Tables, and Databases 79
Displaying System and Network Statistics 80
Displaying BGP Process Information 82
Monitoring BGP Update Groups 83
Configuring BGP Nonstop Routing 84
Disable BGP Nonstop Routing 84
Re-enable BGP Nonstop Routing 84
Configuring BGP Additional Paths 85
Originating Prefixes with AiGP 87
Configuring VRF Dynamic Route Leaking 88
Configuration Examples for Implementing BGP 89
Enabling BGP: Example 89
Displaying BGP Update Groups: Example 91
BGP Neighbor Configuration: Example 91
BGP Confederation: Example 92
BGP Route Reflector: Example 94
BGP Nonstop Routing Configuration: Example 94
Primary Backup Path Installation: Example 94
Originating Prefixes With AiGP: Example 94
VRF Dynamic Route Leaking Configuration: Example 95
Flow-tag propagation 95
Restrictions for Flow-Tag Propagation 95
Configuring Destination-Based Flow-Tag Propagation 96
Where to Go Next 99
Additional References 99
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Implementing BGP Flowspec 103
CHAPTER 3
BGP Flow Specification 103
Limitations 104
BGP Flowspec Conceptual Architecture 104
Information About Implementing BGP Flowspec 105
Flow Specifications 105
Supported Matching Criteria and Actions 105
Traffic Filtering Actions 109
BGP Flowspec Client-Server (Controller) Model and Configuration with ePBR 110
Configuring BGP Flowspec with ePBR 112
Enable BGP Flowspec 112
Configure a Class Map 113
Configure a Policy Map 115
Link BGP Flowspec to ePBR Policies 116
Verify BGP Flowspec 118
Preserving Redirect Nexthop 120
Validate BGP Flowspec 121
Disabling BGP Flowspec 121
Disable Flowspec Redirect and Validation 122
Configuration Examples for Implementing BGP Flowspec 123
Flowspec Rule Configuration 123
Drop Packet Length 125
Remark DSCP 125
Additional References for BGP Flowspec 125
Implementing BFD 127
CHAPTER 4
Prerequisites for Implementing BFD 127
Restrictions for Implementing BFD 128
Information About BFD 129
Differences in BFD in Cisco IOS XR Software and Cisco IOS Software 129
BFD Modes of Operation 129
BFD Packet Information 130
BFD Source and Destination Ports 130
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BFD Packet Intervals and Failure Detection 131
Priority Settings for BFD Packets 135
BFD for IPv4 135
Enabling BFD on a Static Route 136
BFD for IPv6 137
BFD on Bundled VLANs 137
BFD Over Member Links on Link Bundles 138
Overview of BFD State Change Behavior on Member Links and Bundle Status 138
BFD for MultiHop Paths 140
Setting up BFD Multihop 140
BFD IPv6 Multihop 140
BFD over MPLS Traffic Engineering LSPs 141
BFD Object Tracking 141
How to Configure BFD 142
BFD Configuration Guidelines 142
Configuring BFD Under a Dynamic Routing Protocol or Using a Static Route 142
Enabling BFD on a BGP Neighbor 142
Enabling BFD for OSPF on an Interface 144
Enabling BFD for OSPFv3 on an Interface 145
Configuring BFD on Bundle Member Links 147
Prerequisites for Configuring BFD on Bundle Menmber Links 147
Specifying the BFD Destination Address on a Bundle 147
Enabling BFD Sessions on Bundle Members 148
Configuring the Minimum Thresholds for Maintaining an Active Bundle 148
Configuring BFD Packet Transmission Intervals and Failure Detection Times on a Bundle 149
Configuring Allowable Delays for BFD State Change Notifications Using Timers on a Bundle
151
Enabling Echo Mode to Test the Forwarding Path to a BFD Peer 152
Overriding the Default Echo Packet Source Address 152
Specifying the Echo Packet Source Address Globally for BFD 152
Specifying the Echo Packet Source Address on an Individual Interface or Bundle 153
Configuring BFD Session Teardown Based on Echo Latency Detection 154
Delaying BFD Session Startup Until Verification of Echo Path and Latency 154
Disabling Echo Mode 156
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Disabling Echo Mode on a Router 156
Disabling Echo Mode on an Individual Interface 157
Minimizing BFD Session Flapping Using BFD Dampening 157
Enabling and Disabling IPv6 Checksum Support 158
Enabling and Disabling IPv6 Checksum Calculations for BFD on a Router 158
Enabling and Disabling IPv6 Checksum Calculations for BFD on an Individual Interface or
Bundle 159
Clearing and Displaying BFD Counters 160
Configuring BFD over MPLS Traffic Engineering LSPs 160
Enabling BFD Parameters for BFD over TE Tunnels 160
Configuring BFD Bring up Timeout 162
Configuring BFD Dampening for TE Tunnels 162
Configuring Periodic LSP Ping Requests 164
Configuring BFD at the Tail End 165
Configuring BFD over LSP Sessions on Line Cards 165
Configuring BFD Object Tracking: 166
Configuration Examples for Configuring BFD 167
BFD Over BGP: Example 167
BFD Over OSPF: Examples 167
BFD Over Static Routes: Examples 168
BFD on Bundled VLANs: Example 168
BFD Over Bridge Group Virtual Interface: Example 168
BFD on Bundle Member Links: Examples 170
Echo Packet Source Address: Examples 172
Echo Latency Detection: Examples 172
Echo Startup Validation: Examples 173
BFD Echo Mode Disable: Examples 173
BFD Dampening: Examples 174
BFD IPv6 Checksum: Examples 174
BFD Peers on Routers Running Cisco IOS and Cisco IOS XR Software: Example 175
BFD over MPLS TE LSPs: Examples 175
BFD over MPLS TE Tunnel Head-end Configuration: Example 175
BFD over MPLS TE Tunnel Tail-end Configuration: Example 176
Where to Go Next 176
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Additional References 176
Related Documents 176
Standards 176
RFCs 177
MIBs 177
Technical Assistance 177
Implementing EIGRP 179
CHAPTER 5
Prerequisites for Implementing EIGRP 179
Restrictions for Implementing EIGRP 180
Information About Implementing EIGRP 180
EIGRP Functional Overview 180
EIGRP Features 180
EIGRP Components 181
EIGRP Configuration Grouping 182
EIGRP Configuration Modes 182
EIGRP Interfaces 182
Redistribution for an EIGRP Process 183
Metric Weights for EIGRP Routing 183
Mismatched K Values 183
Goodbye Message 184
Percentage of Link Bandwidth Used for EIGRP Packets 184
Floating Summary Routes for an EIGRP Process 184
Split Horizon for an EIGRP Process 186
Adjustment of Hello Interval and Hold Time for an EIGRP Process 186
Stub Routing for an EIGRP Process 187
Route Policy Options for an EIGRP Process 188
EIGRP v4/v6 Authentication Using Keychain 189
How to Implement EIGRP 189
Enabling EIGRP Routing 189
Configuring Route Summarization for an EIGRP Process 191
Redistributing Routes for EIGRP 192
Creating a Route Policy and Attaching It to an EIGRP Process 194
Configuring Stub Routing for an EIGRP Process 195
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