Reference Guide
IP Prefix Lists......................................................................................................................................110
Implementation Information....................................................................................................... 111
Configuration Task List for Prefix Lists........................................................................................ 111
ACL Resequencing.............................................................................................................................115
Resequencing an ACL or Prefix List............................................................................................ 115
Route Maps........................................................................................................................................ 117
Implementation Information....................................................................................................... 117
Flow-Based Monitoring Support for ACLs........................................................................................117
Behavior of Flow-Based Monitoring...........................................................................................118
Enabling Flow-Based Monitoring................................................................................................119
7 Bidirectional Forwarding Detection (BFD)................................................... 121
How BFD Works.................................................................................................................................121
BFD Packet Format......................................................................................................................122
BFD Sessions................................................................................................................................124
BFD Three-Way Handshake........................................................................................................124
Session State Changes................................................................................................................ 125
Important Points to Remember........................................................................................................126
Configure BFD...................................................................................................................................126
Configure BFD for Physical Ports................................................................................................127
Configure BFD for Static Routes.................................................................................................130
Configure BFD for OSPF............................................................................................................. 132
Configure BFD for OSPFv3..........................................................................................................135
Configure BFD for IS-IS...............................................................................................................136
Configure BFD for BGP............................................................................................................... 139
Configure BFD for VRRP............................................................................................................. 146
Configuring Protocol Liveness................................................................................................... 149
Troubleshooting BFD..................................................................................................................149
8 Border Gateway Protocol IPv4 (BGPv4)....................................................... 151
Autonomous Systems (AS)................................................................................................................ 151
Sessions and Peers............................................................................................................................ 153
Establish a Session.......................................................................................................................154
Route Reflectors................................................................................................................................154
BGP Attributes................................................................................................................................... 155
Best Path Selection Criteria.........................................................................................................156
Weight..........................................................................................................................................158
Local Preference......................................................................................................................... 158
Multi-Exit Discriminators (MEDs)................................................................................................ 159
Origin...........................................................................................................................................160
AS Path......................................................................................................................................... 161
Next Hop...................................................................................................................................... 161