The timer value for single-hop BFD sessions from BGP/SRM is selected in the following manner:
Interface level timers will have the highest priority. If interface level timer is configured, it is always used.
When interface level timer is not configured, then BGP/SRM timer is considered. If both these values are configured, then the lower of the two values is used.
If BGP timer is configured, then the selection of the BGP timer value is based on this hierarchy.
Neighbor level configured interval has the highest priority
Peer-group level intervals are considered next if the Neighbor level timer values are not configured.
Global level configured intervals are considered only when Neighbor level and Peer-group level timer interval configurations are not available.
Note
For multi-hop BFD sessions, all the above considerations apply, except that the interface level timer configuration is always ignored.