Bidirectional Forwarding Detection (BFD) is a network fault detection protocol that provides fast failure detection times, which facilitates faster re-convergence time for dynamic routing protocols. It is independent of media, routing protocol, and data. We recommend enabling BFD when configuring multiple AWS Direct Connect connections or when configuring a single AWS Direct Connect connection and a VPN connection as a back up to ensure fast detection and failover. You can configure BFD to detect link or path failures and update dynamic routing as Direct Connect quickly terminates BGP peering so that backup routes can kick in. This ensures that the Bidirectional Forwarding Detection (BGP) neighbor relationship is quickly torn down instead of waiting for 3 keep-alives to fail at a hold-down time of 90sec.
Asynchronous BFD is automatically enabled for each Direct Connect virtual interface on the AWS side, but it does not take effect until it’s configured on your router. The Direct Connect default sets the BFD liveness detection minimum interval to 300 ms and the BFD liveness detection multiplier to 3.
Before using BFD echo mode with your network device, you must disable the sending of Internet Control Message Protocol (ICMP) and redirect messages with the “no ip redirect” command to avoid high CPU utilization.