Continue Clause........................................................................................................................................................ 115
IP Fragment Handling..................................................................................................................................................... 116
IP Fragments ACL Examples................................................................................................................................... 116
Layer 4 ACL Rules Examples................................................................................................................................... 116
Congure a Standard IP ACL.........................................................................................................................................117
Conguring a Standard IP ACL Filter......................................................................................................................118
Congure an Extended IP ACL......................................................................................................................................119
Conguring Filters with a Sequence Number........................................................................................................119
Conguring Filters Without a Sequence Number.................................................................................................120
Congure Layer 2 and Layer 3 ACLs............................................................................................................................ 121
Assign an IP ACL to an Interface..................................................................................................................................122
Applying an IP ACL.........................................................................................................................................................122
Counting ACL Hits....................................................................................................................................................123
Congure Ingress ACLs................................................................................................................................................. 123
Congure Egress ACLs.................................................................................................................................................. 123
Applying Egress Layer 3 ACLs (Control-Plane).................................................................................................... 124
IP Prex Lists.................................................................................................................................................................. 125
Implementation Information.................................................................................................................................... 125
Conguration Task List for Prex Lists.................................................................................................................. 125
ACL Resequencing......................................................................................................................................................... 129
Resequencing an ACL or Prex List.......................................................................................................................129
Route Maps......................................................................................................................................................................131
Implementation Information..................................................................................................................................... 131
Logging of ACL Processes............................................................................................................................................. 131
Guidelines for Conguring ACL Logging................................................................................................................132
Conguring ACL Logging.........................................................................................................................................132
Flow-Based Monitoring..................................................................................................................................................133
Behavior of Flow-Based Monitoring.......................................................................................................................133
Enabling Flow-Based Monitoring............................................................................................................................135
8 Bidirectional Forwarding Detection (BFD)...................................................................................................137
How BFD Works..............................................................................................................................................................137
BFD Packet Format..................................................................................................................................................138
BFD Sessions............................................................................................................................................................ 139
BFD Three-Way Handshake.................................................................................................................................... 140
Session State Changes............................................................................................................................................142
Important Points to Remember.................................................................................................................................... 142
Congure BFD................................................................................................................................................................ 142
Congure BFD for Physical Ports...........................................................................................................................143
Congure BFD for Static Routes............................................................................................................................144
Congure BFD for OSPF......................................................................................................................................... 147
Congure BFD for OSPFv3......................................................................................................................................151
Congure BFD for IS-IS...........................................................................................................................................154
Congure BFD for BGP...........................................................................................................................................156
Congure BFD for VRRP.........................................................................................................................................165
Conguring Protocol Liveness................................................................................................................................168
6
Contents