Users Guide

● multiplier number — Enter the number of consecutive packets that must not be received from a BFD peer before
the session state changes to Down, from 3 to 50. The default is 3.
● role {active | passive} — Enter active if the router initiates BFD sessions. Both BFD peers can be active
at the same time. Enter passive if the router does not initiate BFD sessions, and only responds to a request from an
active BFD to initialize a session. The default is active.
2. Enable BFD globally in CONFIGURATION mode.
bfd enable
To verify that BFD is globally enabled, use the show running-config bfd command.
BFD global configuration
OS10(config)# bfd interval 250 min_rx 300 multiplier 4 role passive
OS10(config)# bfd enable
OS10(config)# do show running-config bfd
!
bfd enable
bfd interval 250 min_rx 300 multiplier 4 role passive
View information about active BFD neighbors
OS10#show bfd neighbors active
* - Active session role
-----------------------------------------------------------------------------------------
--
LocalAddr RemoteAddr Interface State RxInt TxInt Mult VRF
Clients
-----------------------------------------------------------------------------------------
--
* 100.100.1.1 100.100.1.2 ethernet1/1/26:1 up 200 200 3 red ospfv2
* 100.100.3.1 100.100.3.2 ethernet1/1/26:3 up 200 200 3 default ospfv2
* 200.1.1.2 200.1.1.1 vlan102 up 200 200 3 black bgp
* 200.1.5.2 200.1.5.1 vlan105 up 200 200 3 default ospfv2
* 200.1.11.2 200.1.11.1 vlan111 up 200 200 3 green rtmv4
* 200.1.12.2 200.1.12.1 vlan112 up 200 200 3 default rtmv4
* 201.1.1.2 201.1.1.1 vlan101 up 200 200 3 green ospfv2
BFD for BGP
In a BGP core network, BFD enables faster network reconvergence. BFD rapidly detects communication failures in BGP
fast-forwarding paths between internal BGP (iBGP) and external BGP (eBGP) peers. BFD for BGP is supported on physical,
port-channel, and VLAN interfaces. BFD for BGP does not support the BGP multihop feature.
Before configuring BFD for BGP, first configure BGP on the interconnecting routers. For more information, see Border Gateway
Protocol.
NOTE:
When you clear the BGP instance or flaps ICL interface, the BFD sessions goes down and comes back up. This
happens when the default timer is set to 200ms and multiplier as 3. You can avoid this by customizing the timer to 200ms
and multiplier as 6.
BFD for BGP example
In this BFD for BGP configuration example, Router 1 and Router 2 use eBGP in a transit network to interconnect AS1 and AS2.
The eBGP routers exchange information with each other and with iBGP routers to maintain connectivity and accessibility within
each autonomous system.
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Layer 3