Users Guide

Congure an Extended IP ACL.....................................................................................................................................109
Conguring Filters with a Sequence Number.......................................................................................................109
Conguring Filters Without a Sequence Number................................................................................................. 110
Congure Layer 2 and Layer 3 ACLs............................................................................................................................. 111
Assign an IP ACL to an Interface................................................................................................................................... 111
Applying an IP ACL..........................................................................................................................................................112
Counting ACL Hits.....................................................................................................................................................112
Congure Ingress ACLs.................................................................................................................................................. 113
Congure Egress ACLs...................................................................................................................................................113
Applying Egress Layer 3 ACLs (Control-Plane)..................................................................................................... 114
Conguring UDF ACL..................................................................................................................................................... 114
IP Prex Lists................................................................................................................................................................... 117
Implementation Information..................................................................................................................................... 117
Conguration Task List for Prex Lists................................................................................................................... 117
ACL Resequencing..........................................................................................................................................................121
Resequencing an ACL or Prex List........................................................................................................................121
Route Maps.....................................................................................................................................................................122
Implementation Information.................................................................................................................................... 123
Flow-Based Monitoring Support for ACLs.................................................................................................................. 123
Behavior of Flow-Based Monitoring.......................................................................................................................123
Enabling Flow-Based Monitoring............................................................................................................................124
8 Bidirectional Forwarding Detection (BFD).................................................................................................. 126
How BFD Works............................................................................................................................................................. 126
BFD Packet Format..................................................................................................................................................127
BFD Sessions............................................................................................................................................................ 128
BFD Three-Way Handshake.................................................................................................................................... 129
Session State Changes.............................................................................................................................................131
Important Points to Remember..................................................................................................................................... 131
Congure BFD................................................................................................................................................................. 131
Congure BFD for Physical Ports...........................................................................................................................132
Congure BFD for Static Routes............................................................................................................................135
Congure BFD for OSPF.........................................................................................................................................136
Congure BFD for OSPFv3.....................................................................................................................................139
Congure BFD for IS-IS...........................................................................................................................................140
Congure BFD for BGP........................................................................................................................................... 142
Congure BFD for VRRP.........................................................................................................................................149
Conguring Protocol Liveness.................................................................................................................................151
Troubleshooting BFD.................................................................................................................................................151
9 Border Gateway Protocol IPv4 (BGPv4).................................................................................................... 153
Autonomous Systems (AS)........................................................................................................................................... 153
Sessions and Peers........................................................................................................................................................ 155
Establish a Session...................................................................................................................................................155
Route Reectors.............................................................................................................................................................156
BGP Attributes................................................................................................................................................................157
Best Path Selection Criteria.................................................................................................................................... 157
6
Contents