Note When unicast reverse path forwarding (uRPF) is enabled on an interface,asynchronous mode without echo is usually deployed to avoid inadvertently dropping
looped echo packets. The IOS command to disable echo mode on an interface is no bfd
echo . The IOS XR command is bfd interface interface-type interface-number echo disable
The primary benefit of the echo function is that it more accurately tests the forwarding path between the two routers in comparison with the BFD without echo.