White Papers

Table Of Contents
IP Prefix Lists.................................................................................................................................................................... 116
Configuration Task List for Prefix Lists.................................................................................................................117
ACL Remarks.................................................................................................................................................................... 120
Configuring a Remark............................................................................................................................................... 120
Deleting a Remark...................................................................................................................................................... 121
ACL Resequencing........................................................................................................................................................... 121
Resequencing an ACL or Prefix List......................................................................................................................122
Route Maps.......................................................................................................................................................................123
Important Points to Remember....................................................................................................................................123
Configuration Task List for Route Maps.............................................................................................................. 123
Configuring Match Routes...................................................................................................................................... 125
Configuring Set Conditions..................................................................................................................................... 126
Configure a Route Map for Route Redistribution.............................................................................................. 127
Configure a Route Map for Route Tagging......................................................................................................... 128
Continue Clause......................................................................................................................................................... 128
Logging of ACL Processes............................................................................................................................................ 128
Guidelines for Configuring ACL Logging.............................................................................................................. 129
Configuring ACL Logging......................................................................................................................................... 130
Flow-Based Monitoring.................................................................................................................................................. 130
Enabling Flow-Based Monitoring............................................................................................................................132
Chapter 8: Bidirectional Forwarding Detection (BFD)................................................................ 133
How BFD Works...............................................................................................................................................................133
BFD Packet Format...................................................................................................................................................134
BFD Sessions.............................................................................................................................................................. 135
BFD Three-Way Handshake.................................................................................................................................... 136
Session State Changes............................................................................................................................................. 137
Important Points to Remember.................................................................................................................................... 137
Configure BFD.................................................................................................................................................................. 137
Configure BFD for Physical Ports..........................................................................................................................138
Configure BFD for Static Routes........................................................................................................................... 139
Configure BFD for OSPF..........................................................................................................................................142
Configure BFD for OSPFv3.....................................................................................................................................145
Configure BFD for IS-IS........................................................................................................................................... 148
Configure BFD for BGP............................................................................................................................................150
Configure BFD for VRRP......................................................................................................................................... 156
Configuring Protocol Liveness................................................................................................................................159
Troubleshooting BFD................................................................................................................................................ 159
Chapter 9: Border Gateway Protocol (BGP)............................................................................... 161
BGP IP version 4 (BGPv4) Overview..........................................................................................................................161
BGP Autonomous Systems...................................................................................................................................... 161
AS4 Number Representation.................................................................................................................................. 163
Four-Byte AS Numbers............................................................................................................................................ 165
BGP router ID............................................................................................................................................................. 165
Sessions and Peers....................................................................................................................................................165
Establish a Session.................................................................................................................................................... 165
BGP Attributes for selecting Best Path............................................................................................................... 166
Multiprotocol BGP...................................................................................................................................................... 171
6
Contents