Bidirectional Forwarding Detection (BFD) is a simple Hello protocol used between two peers. In BFD, peer systems periodically transmit BFD packets to each other. If one of the systems does not receive a BFD packet after a certain period of time, the system assumes that the link or other system is not operating.
A path is considered operational when bidirectional communication is established between systems. However, this does not preclude the use of unidirectional links.
BFD provides low-overhead, short-duration failure detection between two systems. BFD also provides a single mechanism for connectivity detection over any media, at any protocol layer.
Because BFD sends rapid failure-detection notifications to the routing protocols that run on the local system, which initiates routing table recalculations, BFD helps reduce network convergence time.
BFD supports IPv4/IPv6 single hop detection for static routes, OSPFv2, OSPFv3, iBGP, iBGPv6. Forwarding path failure detection for Fabric Extend tunnels is supported over an IPv4 network only.
Note
BFD for IPv6 interfaces is a demonstration feature on some products. For more information about feature support, see Fabric Engine Feature Support Matrix.
Note
iBGPv6 is not supported in VRF.