Managing the MPLS BFD Client

Bidirectional Forwarding Detection (BFD) is introduced in Bidirectional Forwarding Detection (BFD).

The MPLS BFD client enables rapid detection of failures between MPLS neighbors on specific VLANs. BFD detects forwarding path failures at a uniform rate, which makes the re-convergence time consistent and predictable and makes network profiling and planning easier for network administrators.

When BFD detects a communication failure, it informs MPLS, which treats the indication as an interface (VLAN) failure. This allows the MPLS protocols to quickly begin using alternate paths to affected neighbors (the methodology for selecting alternate paths is dependent upon the MPLS protocol in use and how it reacts to interface failure conditions). As MPLS connections (LSPs) are removed from the interface, BFD sessions are removed as well, and the interface returns to a state without BFD protection. The MPLS protocol might continue to attempt to reestablish LSP connections across the interface, and if successful, also attempt to establish a BFD session with the corresponding neighbor. MPLS does not process BFD state changes until the BFD session is fully active in the UP state, at which point state changes are processed and the state for LSPs which cross the interface becomes BFD protected.

Note

BFD sessions are established only when both peers select the same LSP route. We recommend that BFD operate only on interfaces that have one peer.