Users Guide

Conguring a Standard IP ACL Filter......................................................................................................................113
Congure an Extended IP ACL......................................................................................................................................114
Conguring Filters with a Sequence Number........................................................................................................114
Conguring Filters Without a Sequence Number................................................................................................. 115
Congure Layer 2 and Layer 3 ACLs............................................................................................................................ 116
Assign an IP ACL to an Interface...................................................................................................................................116
Applying an IP ACL..........................................................................................................................................................116
Counting ACL Hits.....................................................................................................................................................117
Congure Ingress ACLs.................................................................................................................................................. 117
Congure Egress ACLs...................................................................................................................................................118
Applying Egress Layer 3 ACLs (Control-Plane)..................................................................................................... 119
IP Prex Lists...................................................................................................................................................................119
Implementation Information.................................................................................................................................... 120
Conguration Task List for Prex Lists.................................................................................................................. 120
ACL Resequencing......................................................................................................................................................... 123
Resequencing an ACL or Prex List.......................................................................................................................124
Route Maps.....................................................................................................................................................................125
Implementation Information.................................................................................................................................... 125
Flow-Based Monitoring Support for ACLs..................................................................................................................125
Behavior of Flow-Based Monitoring.......................................................................................................................126
Enabling Flow-Based Monitoring............................................................................................................................ 127
7 Bidirectional Forwarding Detection (BFD).................................................................................................. 128
How BFD Works............................................................................................................................................................. 128
BFD Packet Format..................................................................................................................................................129
BFD Sessions............................................................................................................................................................ 130
BFD Three-Way Handshake.....................................................................................................................................131
Session State Changes............................................................................................................................................133
Important Points to Remember.................................................................................................................................... 133
Congure BFD................................................................................................................................................................ 133
Congure BFD for Physical Ports...........................................................................................................................134
Congure BFD for Static Routes............................................................................................................................ 137
Congure BFD for OSPF.........................................................................................................................................138
Congure BFD for OSPFv3......................................................................................................................................141
Congure BFD for IS-IS...........................................................................................................................................142
Congure BFD for BGP........................................................................................................................................... 144
Congure BFD for VRRP..........................................................................................................................................151
Conguring Protocol Liveness................................................................................................................................ 153
Troubleshooting BFD................................................................................................................................................153
8 Border Gateway Protocol IPv4 (BGPv4).................................................................................................... 155
Autonomous Systems (AS)...........................................................................................................................................155
Sessions and Peers.........................................................................................................................................................157
Establish a Session................................................................................................................................................... 157
Route Reectors.............................................................................................................................................................158
BGP Attributes................................................................................................................................................................159
Best Path Selection Criteria....................................................................................................................................159
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