Configuring Filters Without a Sequence Number......................................................................118
Configure Layer 2 and Layer 3 ACLs.................................................................................................119
Assign an IP ACL to an Interface.......................................................................................................119
Applying an IP ACL............................................................................................................................120
Counting ACL Hits.......................................................................................................................121
Configure Ingress ACLs.....................................................................................................................121
Configure Egress ACLs......................................................................................................................122
Applying Egress Layer 3 ACLs (Control-Plane)..........................................................................122
IP Prefix Lists......................................................................................................................................123
Implementation Information.......................................................................................................123
Configuration Task List for Prefix Lists.......................................................................................123
ACL Resequencing............................................................................................................................127
Resequencing an ACL or Prefix List............................................................................................128
Route Maps........................................................................................................................................129
Implementation Information......................................................................................................130
Flow-Based Monitoring Support for ACLs.......................................................................................130
Behavior of Flow-Based Monitoring...........................................................................................130
Enabling Flow-Based Monitoring...............................................................................................132
7 Bidirectional Forwarding Detection (BFD)...................................................134
How BFD Works................................................................................................................................134
BFD Packet Format......................................................................................................................135
BFD Sessions................................................................................................................................137
BFD Three-Way Handshake........................................................................................................137
Session State Changes................................................................................................................138
Important Points to Remember........................................................................................................139
Configure BFD...................................................................................................................................139
Configure BFD for Physical Ports...............................................................................................140
Configure BFD for Static Routes.................................................................................................143
Configure BFD for OSPF.............................................................................................................145
Configure BFD for OSPFv3.........................................................................................................148
Configure BFD for IS-IS...............................................................................................................149
Configure BFD for BGP................................................................................................................151
Configure BFD for VRRP.............................................................................................................158
Configuring Protocol Liveness....................................................................................................161
Troubleshooting BFD..................................................................................................................162
8 Border Gateway Protocol IPv4 (BGPv4)...................................................... 164
Autonomous Systems (AS)................................................................................................................164
Sessions and Peers............................................................................................................................166
Establish a Session.......................................................................................................................167
Route Reflectors................................................................................................................................168
6