Symptom

On software upgrade from XR 5.3.0 to 5.3.1, BFD sessions over Bundle interfaces are created in Cisco (default) mode even though the router had BFD global configuration to create Bundle BFD sessions in IETF mode.

Conditions

Router running IOS-XR 5.3.0 (or 5.2.0 - 5.2.4) software with BFD bundle mode IETF configuration upgraded to version 5.3.1 or later.

Workaround

User have to migrate to per-interface BFD mode config under Bundle interfaces, new config CLI added from 5.3.1 onwards.

Further Problem Description