###[Configuring Bidirectional Forwarding Detection on the Cisco ASR 9000 Series Router](http://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k_r3-9/interfaces/configuration/guide/hc39asr9kbook/hc39bifw.pdf)

**Restrictions for Configuring BFD**

The following restrictions apply to BFD:

 1. If you are using BFD with uRPF on a particular interface, then you need to use the `echo disable` command to disable echo mode on that interface; otherwise, echo packets are rejected. You can disable echo mode for the entire router, or for an individual interface.
 2. Only the static, OSPF, and IS-IS applications are supported on BFD over bundle VLANs.