Interworking Between BFD and OSPFv3

This section describes the application scenario of interworking between BFD and OSPFv3.

Applicable Environment

A link fault or the change of topology may lead to rerouting in a network. The short-duration convergence of a routing protocol is important for the improvement of availability of the network. A feasible solution is to fast detect the fault and notify the fault to the routing protocol immediately.

In the BFD-OSPFv3 interworking, OSPFv3 is associated with a BFD session. The BFD session fast detects a link fault and notifies OSPFv3 of the fault. In this manner, OSPFv3 speeds up the response to the change of the network topology.

Table 1 shows statistics of convergence speeds when OSPFv3 is and is not associated with a BFD session.

**Table 1** Statistics of OSPFv3 convergence speeds
Associated with BFD or Not	Link Fault Detection Mechanism	Convergence Speed
Not associated with BFD	Timeout of the OSPFv3 Hello keepalive timer	At the second level
Associated with BFD	BFD session in the Down state	At the millisecond level

Typical Application

As shown in Figure 1, OSPFv3 runs among Router_A, Router_B, and Router_C which are mutual neighbors. The link from Router_A to Router_B serves as the active link whereas the link from Router_A to Router_C to Router_B serves as the standby link.

Create a BFD session on the link between Router_A and Router_B. Therefore, when the link status changes, the convergence speed of OSPFv3 increases. If the link between Router_A and Router_B fails, BFD rapidly identifies the fault and notifies OSPFv3 of the fault. Therefore, the service traffic is switched to the standby link.

Figure 1 Networking diagram of BFD-OSPFv3 interworking