BFD Echo Function

The BFD Echo function checks the connectivity of the forwarding link by looping back packets.

You can use the BFD Echo function when one of two directly connected devices does not support BFD. In this case, you can configure BFD Echo on the BFD-supporting device. That device sends an Echo Request packet to the remote device. The remote device then sends the Echo Request packet back along the same path to detect the connectivity of the forwarding link.

The BFD Echo function only applies to single-hop BFD sessions.

Application

Figure 1 BFD Echo

In Figure 1, SwitchA supports BFD, but SwitchB does not. BFD Echo is configured on SwitchA to monitor the connectivity of the single-hop path between SwitchA and SwitchB. Once SwitchB receives a BFD Echo packet from SwitchA, SwitchB loops back the packet at the network layer.