Setup Guide

Applying Egress Layer 3 ACLs (Control-Plane).................................................................................................... 108
IP Prex Lists.................................................................................................................................................................. 108
Implementation Information.................................................................................................................................... 109
Conguration Task List for Prex Lists..................................................................................................................109
ACL Remarks................................................................................................................................................................... 112
Conguring a Remark............................................................................................................................................... 112
Deleting a Remark.....................................................................................................................................................113
ACL Resequencing..........................................................................................................................................................114
Resequencing an ACL or Prex List........................................................................................................................114
Route Maps......................................................................................................................................................................115
Implementation Information..................................................................................................................................... 115
Flow-Based Monitoring.................................................................................................................................................. 116
Behavior of Flow-Based Monitoring....................................................................................................................... 116
Enabling Flow-Based Monitoring.............................................................................................................................117
Conguring IP Mirror Access Group.............................................................................................................................118
Sample Conguration............................................................................................................................................... 118
Example of viewing IP mirror–access–group applied to an Interface................................................................ 118
7 Bidirectional Forwarding Detection (BFD)................................................................................................... 119
How BFD Works..............................................................................................................................................................119
BFD Packet Format..................................................................................................................................................120
BFD Sessions............................................................................................................................................................. 121
BFD Three-Way Handshake.................................................................................................................................... 122
Session State Changes............................................................................................................................................ 124
Important Points to Remember.................................................................................................................................... 124
Congure BFD................................................................................................................................................................ 125
Congure BFD for Physical Ports...........................................................................................................................125
Congure BFD for Static Routes............................................................................................................................126
Congure BFD for IPv6 Static Routes...................................................................................................................130
Congure BFD for OSPF.........................................................................................................................................132
Congure BFD for OSPFv3.....................................................................................................................................137
Congure BFD for IS-IS...........................................................................................................................................140
Congure BFD for BGP........................................................................................................................................... 142
Congure BFD for VRRP.........................................................................................................................................148
Conguring Protocol Liveness.................................................................................................................................151
8 Border Gateway Protocol (BGP)................................................................................................................ 152
BGP IP version 4 (BGPv4) Overview.......................................................................................................................... 152
BGP Autonomous Systems.....................................................................................................................................152
AS4 Number Representation.................................................................................................................................. 154
Four-Byte AS Numbers........................................................................................................................................... 156
BGP router ID............................................................................................................................................................156
Sessions and Peers.................................................................................................................................................. 156
Establish a Session................................................................................................................................................... 157
BGP Attributes for selecting Best Path.................................................................................................................157
Multiprotocol BGP....................................................................................................................................................162
6
Contents