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Assign an IP ACL to an Interface...................................................................................................................................115
Applying an IP ACL..........................................................................................................................................................115
Counting ACL Hits.................................................................................................................................................... 116
Congure Ingress ACLs.................................................................................................................................................. 116
Congure Egress ACLs...................................................................................................................................................117
Applying Egress Layer 3 ACLs (Control-Plane)..................................................................................................... 117
IP Prex Lists...................................................................................................................................................................118
Implementation Information..................................................................................................................................... 118
Conguration Task List for Prex Lists...................................................................................................................119
ACL Resequencing......................................................................................................................................................... 122
Resequencing an ACL or Prex List.......................................................................................................................123
Route Maps..................................................................................................................................................................... 124
Implementation Information.....................................................................................................................................124
Flow-Based Monitoring..................................................................................................................................................124
Behavior of Flow-Based Monitoring.......................................................................................................................124
Enabling Flow-Based Monitoring............................................................................................................................126
Conguring IP Mirror Access Group.............................................................................................................................127
Sample Conguration...............................................................................................................................................128
Example of viewing IP mirror–access–group applied to an Interface................................................................128
7 Bidirectional Forwarding Detection (BFD).................................................................................................. 129
How BFD Works............................................................................................................................................................. 129
BFD Packet Format..................................................................................................................................................130
BFD Sessions............................................................................................................................................................. 131
BFD Three-Way Handshake.................................................................................................................................... 132
Session State Changes............................................................................................................................................134
Important Points to Remember.................................................................................................................................... 134
Congure BFD................................................................................................................................................................ 134
Congure BFD for Physical Ports...........................................................................................................................135
Congure BFD for Static Routes............................................................................................................................137
Congure BFD for OSPF.........................................................................................................................................139
Congure BFD for OSPFv3.....................................................................................................................................143
Congure BFD for IS-IS...........................................................................................................................................146
Congure BFD for BGP........................................................................................................................................... 148
Congure BFD for VRRP.........................................................................................................................................156
Conguring Protocol Liveness................................................................................................................................158
8 Border Gateway Protocol IPv4 (BGPv4).................................................................................................... 159
Autonomous Systems (AS)...........................................................................................................................................159
Sessions and Peers......................................................................................................................................................... 161
Establish a Session....................................................................................................................................................161
Route Reectors.............................................................................................................................................................162
BGP Attributes................................................................................................................................................................163
Best Path Selection Criteria....................................................................................................................................163
Weight........................................................................................................................................................................165
Local Preference.......................................................................................................................................................165
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