RDI provides a mechanism whereby the source MEP can be informed of a downstream failure on an LSP, and can either raise an alarm, or initiate a protection switching operation. In the case of BFD based CC/CV, RDI is communicated using the BFD diagnostic field in BFD CC/CV messages. The following diagnostic codes are supported:
1 indicates Control Detection Time Expired.
9 indicates mis-connectivity defect.