BFD for Static Routes

Different from dynamic routing protocols, static routes do not have a detection mechanism. If a fault occurs on a network, an administrator must manually address it. Bidirectional Forwarding Detection (BFD) for static routes is introduced to associate a static route with a BFD session so that the BFD session can detect the status of the link that the static route passes through.

After BFD for static routes is configured, each static route can be associated with a BFD session. In addition to route selection rules, whether a static route can be selected as the optimal route is subject to BFD session status.

• If a BFD session associated with a static route detects a link failure when the BFD session is Down, the BFD session reports the link failure to the system. The system then deletes the static route from the IP routing table.

• If a BFD session associated with a static route detects that a faulty link recovers when the BFD session is Up, the BFD session reports the fault recovery to the system. The system then adds the static route to the IP routing table again.

• By default, a static route can still be selected even though the BFD session associated with it is AdminDown (triggered by the shutdown command run either locally or remotely). If a device is restarted, the BFD session needs to be re-negotiated. In this case, whether the static route associated with the BFD session can be selected as the optimal route is subject to the re-negotiated BFD session status.

BFD for static routes has two detection modes:

• Single-hop detection

  In single-hop detection mode, the configured outbound interface and next hop address are the information about the directly connected next hop. The outbound interface associated with the BFD session is the outbound interface of the static route, and the peer address is the next hop address of the static route.

• Multi-hop detection

  In multi-hop detection mode, only the next hop address is configured. Therefore, the static route must recurse to the directly connected next hop and outbound interface. The peer address of the BFD session is the original next hop address of the static route, and the outbound interface is not specified. In most cases, the original next hop is an indirect next hop. Multi-hop detection is performed on the static routes that support route recursion.

For details about BFD, see the HUAWEI NetEngine 8000 F Series RouterFeature Description - Network Reliability.