The bi-directional Forwarding Detection (BFD) protocol rapidly detects communication failures between two adjacent routers. BFD replaces link-state detection mechanisms in existing routing protocols. It also provides a failure detection solution for links with no routing protocols.
BFD provides forwarding-path failure detection in milliseconds instead of seconds. BFD is independent of routing protocols and provides consistent network failure detection. BFD eliminates multiple protocol-dependent timers and methods. Networks converge is faster because BFD triggers link-state changes in the routing protocol sooner and more consistently.
Using BFD, two neighboring routers running BFD establish a session using a three-way handshake. After the session is established, the routers exchange periodic control packets at sub second intervals. If a router does not receive a hello packet within the specified time, routing protocols are notified that the forwarding path is down.
BFD sends a control packet when there is a state change or change in a session parameter. These control packets are sent without regard to transmit and receive intervals in a routing protocol.
BFD is an independent and generic protocol, which all media, topologies, and routing protocols can support using any encapsulation. OS10 implements BFD at Layer 3 (L3) and with User Datagram Protocol (UDP) encapsulation. BFD is supported on static and dynamic routing protocols, such as static route, OSPF, OSPFv3, and BGP. The system displays BFD state change notifications.
