• Before enabling BFD globally, disable Internet Control Message Protocol (ICMP) redirect messages using the [no] ip icmp redirect command. Additionally, this has to be configured on the VRRP master if the backup has a BFD session monitoring the master.

  • Ensure that virus throttling is disabled before enabling BFD globally.

  • Ensure that BFD timers are configured as per deployment needs. Configuring the timers to be too aggressive (for example, detect-multiplier of 1) can sometimes lead to BFD session flaps depending upon traffic conditions.

  • BFD works only for directly connected neighbors. BFD neighbors must be no more than one IP hop away. Multihop configurations are not supported.

  • Demand mode is not supported.

  • BFD over IPv6 is not supported.

  • Recommended multiplier value should be minimum 3 when min-echo-receive interval or transmit intervals are aggressive.

  • Only BFD version 1 is supported.

  • When BFD sessions are using authentication, the sessions might go down after a switchover.

  • Priority settings for BFD packets: When the interfaces are over-subscribed, BFD packets have to be prioritized, so that these pkts are not overwhelmed by other data packets. CoS values must be explicitly configured in the appropriate egress QoS service policy. CoS values for BFD packets can be set using the qos command. For example, ‘qos udp-port ipv4 3785 priority 6’ assigns 802.1p priority 6 to BFD echo packets. Mapping of 802.1p priorities to egress queues can be found using the show qos queue-config command. These CoS settings must be applied on all intermediate switches if any so that BFD packets get prioritized all through the way.

  • VRRP Advertise interval has to be configured with higher values (ex- 10) to avoid the BFD session flaps due to VRRP packet loss.


Do not clear IP host table using the clear arp command on a system with active BFD sessions, because this can lead to BFD sessions flapping.