Configuring Bidirectional Forwarding Detection

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Configuring Bidirectional Forwarding Detection
The bidirectional forwarding detection (BFD) protocol is a simple hello mechanism that detects failures in a network. BFD works with a wide variety of network environments and topologies. The failure detection timers for BFD have shorter time limits than the failure detection mechanisms of IS-IS, providing faster detection. These timers are also adaptive and can be adjusted to be more or less aggressive. By default, BFD is supported on single-hop static routes.

To enable failure detection, include the bfd-liveness-detection statement:
static route {
    bfd-liveness-detection {
        detection-time {
            threshold milliseconds;
        }
        local-address ip-address;
        minimum-interval milliseconds;
        minimum-receive-interval milliseconds;
        minimum-receive-ttl milliseconds;
        transmit-interval {
            threshold milliseconds;
            minimum-interval milliseconds;
        }

        multiplier number;
        version (0 | 1 | automatic);
    }
}
To specify a threshold for detecting the adaptation of the detection time, include the threshold statement:
static route {
    bfd-liveness-detection {
        detection-time {
            threshold milliseconds;
        }
To specify the minimum transmit and receive interval for failure detection, include the minimum-interval statement:
static route {
    bfd-liveness-detection {
        minimum-interval milliseconds; 
    }
}
To specify only the minimum receive interval for failure detection, include the minimum-receive-interval statement:
static route {
    bfd-liveness-detection {
        minimum-receive-interval milliseconds; 
    }
}
To specify the transmit threshold for detecting the adaptation of the transmit interval, include the threshold statement:
static route {
    bfd-liveness-detection {
        transmit-interval {
            threshold milliseconds;
        }
    }
}
The threshold value must be greater than the transmit interval.

To specify only the minimum transmit interval for failure detection, include the minimum-interval statement:
static route {
    bfd-liveness-detection {
        transmit-interval {
            minimum-interval milliseconds;
        }
    }
To specify the detection time multiplier for failure detection, include the multiplier statement:
static route {
    bfd-liveness-detection {
        multiplier number; 
    }
}
To specify the BFD version, include the version statement:
static route {
    bfd-liveness-detection {
        version (0 | 1 | automatic); 
    }
}
For a list of hierarchy levels at which you can configure these statements, see the statement summary sections for these statements.

NOTE: If BFD is configured only on one end of a static route, the route is removed from the routing table. BFD establishes a session when BFD is configured on both ends of the static route.

NOTE: BFD is not supported for IPv6 or ISO address families.

NOTE: You cannot enable graceful switchover when BFD is configured.

The JUNOS software also supports BFD over multihop static routes. For example, you can configure BFD over a Layer 3 path to provide path integrity over that path. You can limit the number of hops by specifying the time-to-live (TTL).

To configure BFD over multihop static routes, include the following statements:
static route {
    bfd-liveness-detection {
        local-address ip-address; 
        minimum-receive-ttl milliseconds;
    }
}
To specify the source address for the multihop static route and to enable multihop BFD support, include the local-address statement.

To specify the number of hops, include the minimum-receive-ttl statement. For a single-hop BFD session, this value must be 255. The TTL configuration is optional.

For a list of hierarchy levels at which you can configure these statements, see the statement summary sections for these statements.

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