Concept Guide

Congure Layer 2 and Layer 3 ACLs............................................................................................................................ 116
Assign an IP ACL to an Interface...................................................................................................................................117
Applying an IP ACL..........................................................................................................................................................117
Counting ACL Hits.................................................................................................................................................... 118
Congure Ingress ACLs.................................................................................................................................................. 118
Congure Egress ACLs...................................................................................................................................................119
Applying Egress Layer 3 ACLs (Control-Plane).................................................................................................... 120
IP Prex Lists.................................................................................................................................................................. 120
Implementation Information..................................................................................................................................... 121
Conguration Task List for Prex Lists...................................................................................................................121
ACL Remarks.................................................................................................................................................................. 124
Conguring a Remark.............................................................................................................................................. 124
Deleting a Remark.................................................................................................................................................... 125
ACL Resequencing......................................................................................................................................................... 126
Resequencing an ACL or Prex List.......................................................................................................................126
Route Maps..................................................................................................................................................................... 127
Implementation Information.....................................................................................................................................127
Flow-Based Monitoring..................................................................................................................................................128
Behavior of Flow-Based Monitoring.......................................................................................................................128
Enabling Flow-Based Monitoring............................................................................................................................129
Conguring IP Mirror Access Group............................................................................................................................ 130
Sample Conguration................................................................................................................................................131
Example of viewing IP mirror–access–group applied to an Interface................................................................132
7 Bidirectional Forwarding Detection (BFD).................................................................................................. 133
How BFD Works............................................................................................................................................................. 133
BFD Packet Format..................................................................................................................................................134
BFD Sessions............................................................................................................................................................ 135
BFD Three-Way Handshake.................................................................................................................................... 136
Session State Changes............................................................................................................................................138
Important Points to Remember.................................................................................................................................... 138
Congure BFD................................................................................................................................................................ 138
Congure BFD for Physical Ports...........................................................................................................................139
Congure BFD for Static Routes............................................................................................................................140
Congure BFD for IPv6 Static Routes...................................................................................................................144
Congure BFD for OSPF.........................................................................................................................................146
Congure BFD for OSPFv3.....................................................................................................................................150
Congure BFD for IS-IS...........................................................................................................................................153
Congure BFD for BGP...........................................................................................................................................155
Congure BFD for VRRP.........................................................................................................................................163
Conguring Protocol Liveness................................................................................................................................165
8 Border Gateway Protocol (BGP)................................................................................................................ 166
BGP IP version 4 (BGPv4) Overview..........................................................................................................................166
BGP Autonomous Systems........................................................................................................................................... 167
AS4 Number Representation.................................................................................................................................. 168
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