BFD Support for BGP

BFD support for BGP4 and BGP4+ can be configured so that BGP is a registered protocol with BFD, and forwarding path detection failure messages are received from BFD. BFD for BGP is disabled by default. When BFD support for BGP is enabled, BFD rapidly detects faults on links between BGP peers and reports faults to BGP. BFD for BGP is supported for both single-hop and multihop iBGP and eBGP sessions with IPv4 or IPv6 neighbors. BFD for BGP is supported for both the default VRF and nondefault VRF instances.

BFD and the BFD session parameters, as well as active or passive mode, can be configured at a global VRF level and at a neighbor or peer level.

Consider the following when configuring BFD for BGP:

  • BGP initiates a BFD session when BFD is enabled at the BGP global or peer level and the BGP neighbor state transitions to the Established state. BGP tears down the session when the BGP neighbor state moves out of the Established state.
  • When BGP receives notification from BFD of a state change to up, BGP marks the interface level BFD state as up and stops the holdover timer if it has been configured.
  • When BGP receives notification from BFD of a state change to admin down, BGP marks the interface level BFD state as down.
  • When BGP receives notification from BFD of a state change to down, the BGP neighbor transitions to idle, forcing the necessary route calculation for the NLRIs that are learned from the peer. If the holdover timer is configured, BGP is not immediately notified about the down state and the holdover timer begins. If the configured holdover time interval expires, BGP is notified about the session failure and marks the interface level session as down. The BGP neighbor transitions to idle.

For detailed configuration examples that include iBGP and eBGP configurations, refer to BFD Configuration Examples.

In this section:

  1. Configuring BFD for BGP
    BFD can be enabled and BFD session parameters can be set globally for BGP-enabled interfaces. The following task enables BFD globally for BGP, configures the BFD session parameters, and sets the BFD holdover interval.
  2. Configuring BFD for BGP for a Nondefault VRF Instance
    BFD can be enabled and BFD session parameters can be set globally for BGP-enabled interfaces for a nondefault VRF instance. The following task enables BFD globally for BGP, configures the BFD session parameters, and sets the BFD holdover interval for a nondefault VRF instance.
  3. Enabling BFD Sessions for a BGP Neighbor
    BFD sessions can be configured for BGP neighbors. The following task enables a BFD session for a BGP neighbor with the IP address 10.2.1.1 and configures the BFD session parameters.
  4. Enabling BFD Sessions for a BGP Peer Group
    BFD sessions can be configured for BGP peer groups. The following task enables a BFD session for a BGP peer group called “mypeergroup” and configures the BFD session parameters and holdover interval.
  5. Enabling BFD Sessions for a BGP Neighbor for a Nondefault VRF Instance
    BFD sessions can be configured for specified BGP neighbors in a nondefault VRF instance for both the IPv4 and IPv6 unicast address families The following task enables a BFD session for a BGP neighbor with the IP address 10.5.1.1 and configures the BFD session parameters for VRF instance “red”.
  6. Setting a BFD Session as Passive
    BFD sessions with BGP neighbors can be set to passive. The following example configures BFD for a BGP neighbor with the IP address 10.6.1.1 and sets the BFD session as passive.
  7. Disabling a BFD Session for a BGP Neighbor
    BFD sessions can be disabled for BGP neighbors or peer groups. The following task disables BFD for a BGP neighbor with the IPv6 address 2001:2018:8192::124.
Parent topic: BFD