Reference Guide

Continue Clause............................................................................................................................................. 107
7 Bidirectional Forwarding Detection (BFD)..........................................................................109
How BFD Works....................................................................................................................................................109
BFD Packet Format.........................................................................................................................................110
BFD Sessions................................................................................................................................................. 111
BFD Three-Way Handshake...........................................................................................................................112
Session State Changes.................................................................................................................................. 114
Important Points to Remember.............................................................................................................................114
Configure BFD.......................................................................................................................................................115
Configure BFD for Physical Ports...................................................................................................................115
Configure BFD for Static Routes.................................................................................................................... 118
Configure BFD for OSPF................................................................................................................................. 120
Configure BFD for OSPFv3..............................................................................................................................123
Configure BFD for IS-IS..................................................................................................................................124
Configure BFD for BGP...................................................................................................................................126
Configure BFD for VRRP.................................................................................................................................133
Configuring Protocol Liveness....................................................................................................................... 136
Troubleshooting BFD......................................................................................................................................136
8 Border Gateway Protocol IPv4 (BGPv4)..............................................................................139
Autonomous Systems (AS)................................................................................................................................... 139
Sessions and Peers.............................................................................................................................................. 141
Establish a Session........................................................................................................................................ 142
Route Reflectors................................................................................................................................................... 142
Communities...................................................................................................................................................143
BGP Attributes...................................................................................................................................................... 143
Best Path Selection Criteria...........................................................................................................................144
Weight............................................................................................................................................................146
Local Preference............................................................................................................................................146
Multi-Exit Discriminators (MEDs)...................................................................................................................147
Origin.............................................................................................................................................................. 148
AS Path...........................................................................................................................................................149
Next Hop.........................................................................................................................................................149
Multiprotocol BGP................................................................................................................................................ 149
Implement BGP with FTOS....................................................................................................................................150
Additional Path (Add-Path) Support...............................................................................................................150
Advertise IGP Cost as MED for Redistributed Routes....................................................................................150
Ignore Router-ID for Some Best-Path Calculations.......................................................................................151
Four-Byte AS Numbers.................................................................................................................................. 151
AS4 Number Representation..........................................................................................................................151
AS Number Migration.................................................................................................................................... 153