Dell EMC SmartFabric OS10 User Guide Release 10.5.0

Bidirectional Forwarding Detection

The Bidirectional 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. Because BFD is independent of routing protocols, it 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.

BFD is a simple hello mechanism. 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.

In addition, 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 VRRP, OSPF, OSPFv3, IS-IS, and BGP.

The system displays BFD state change notifications.