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Configuring BFD for RSVP LSPs

BFD for RSVP supports unicast IPv4 LSPs. When BFD is configured for an RSVP LSP on the ingress router, it is enabled on the primary path and on all standby secondary paths for that LSP. You can enable BFD for all LSPs on a router or for specific LSPs. If you configure BFD for a specific LSP, whatever values configured globally for BFD are overridden. The BFD sessions originate only at the ingress router and terminate at the egress router.

An error is logged whenever a BFD session for a path fails. The following shows how BFD for RSVP LSP log messages might appear:

RPD_MPLS_PATH_BFD_UP: MPLS BFD session for path path1 up on LSP R0_to_R3
RPD_MPLS_PATH_BFD_DOWN: MPLS BFD session for path path1 down on LSP R0_to_R3

You can configure BFD for all of the RSVP LSPs on the router, a specific LSP, or the primary path of a specific LSP. To configure BFD for RSVP LSPs, include the oam and bfd-liveness-detection statements.




oam {



bfd-liveness-detection {
failure-action teardown;
minimum-interval milliseconds;
minimum-receive-interval milliseconds;
minimum-transmit-interval milliseconds;
multiplier detection-time-multiplier;
}


}

You can configure this statement at the following hierarchy levels:

[edit protocols mpls]
[edit protocols mpls label-switched-path lsp-name]
[edit protocols mpls label-switched-path lsp-name primary path-name]

The bfd-liveness-detection statement includes the following options:

failure-action teardown—When the BFD session for an RSVP LSP goes down, the LSP is torn down and resignaled. Traffic can be switched to a standby LSP if one is configured and available. Any actions performed are logged.
minimum-interval—Specifies the minimum transmit and receive interval.
minimum-receive-interval—Specifies the minimum receive interval. The range is from 1 through 255,000 milliseconds.
minimum-transmit-interval—Specifies the minimum transmit interval. The range is from 1 through 255,000 milliseconds.
multiplier—Specifies the detection time multiplier. The range is from 1 through 255.

Note: To avoid triggering false negatives, configure a BFD fault detection time that is longer than the fast reroute time.

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