Users Guide

Applying an IP ACL..........................................................................................................................................................114
Counting ACL Hits.................................................................................................................................................... 115
Congure Ingress ACLs.................................................................................................................................................. 115
Congure Egress ACLs...................................................................................................................................................116
Applying Egress Layer 3 ACLs (Control-Plane)..................................................................................................... 117
IP Prex Lists................................................................................................................................................................... 117
Implementation Information..................................................................................................................................... 118
Conguration Task List for Prex Lists...................................................................................................................118
ACL Resequencing..........................................................................................................................................................121
Resequencing an ACL or Prex List.......................................................................................................................122
Route Maps.....................................................................................................................................................................123
Implementation Information.................................................................................................................................... 123
Flow-Based Monitoring Support for ACLs.................................................................................................................. 123
Behavior of Flow-Based Monitoring.......................................................................................................................124
Enabling Flow-Based Monitoring............................................................................................................................125
Conguring IP Mirror Access Group............................................................................................................................ 126
Sample Conguration...............................................................................................................................................127
Example of viewing IP mirror–access–group applied to an Interface................................................................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............................................................................................................................135
Congure BFD for OSPF.........................................................................................................................................138
Congure BFD for OSPFv3......................................................................................................................................141
Congure BFD for IS-IS...........................................................................................................................................143
Congure BFD for BGP...........................................................................................................................................145
Congure BFD for VRRP.........................................................................................................................................152
Conguring Protocol Liveness................................................................................................................................155
Troubleshooting BFD................................................................................................................................................155
8 Border Gateway Protocol IPv4 (BGPv4).....................................................................................................157
Autonomous Systems (AS)........................................................................................................................................... 157
Sessions and Peers........................................................................................................................................................ 159
Establish a Session...................................................................................................................................................159
Route Reectors.............................................................................................................................................................160
BGP Attributes................................................................................................................................................................ 161
Best Path Selection Criteria.....................................................................................................................................161
Weight........................................................................................................................................................................163
Local Preference.......................................................................................................................................................163
6
Contents