LSP Precedence and Interaction

A longest prefix match (LPM) is determined for all packets.

If an LSP next hop is available, routed IP traffic may be forwarded over an LSP using the LSP next hop. With respect to a given prefix, LSP next hops can be either matching or calculated, and can be based on LDP, RSVP-TE, or static LSPs. Matching LSP next hops are preferred over calculated LSP next hops. RSVP-TE LSPs are preferred over LDP LSPs, and LDP LSPs are preferred over static LSPs. Also, RSVP-TE LSPs and static LSPs can be individually configured to enable or disable their use as LSP next hops.

Therefore, if a more preferred LSP is established, routed IP traffic may begin to use a new LSP next hop. Likewise, if a preferred LSP is torn down, routed traffic may begin to use the next best LSP next hop. These changes can take place when there is an OSPF (Open Shortest Path First) routing topology change, an LDP label advertisement event, or a RSVP-TE signaling action.