Ldp Over Rsvp Without Area Boundary; Figure 51: Ldp Over Rsvp Without Abr Stitching Point - Alcatel-Lucent 7450 Manual

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LDP over RSVP Without Area Boundary

The LDP over RSVP capability set includes the ability to stitch LDP-over-RSVP tunnels at

internal (non-ABR) OSPF and IS-IS routers.

"Dest". The first thing that happens is that either OSPF or IS-IS will perform an SPF calculation

resulting in an SPF tree. This tree specifies the lowest possible cost to the destination. In the

example shown, the destination "Dest" is reachable at the lowest cost through router X. The SPF

tree will have the following path: A>C>E>G>X.

Using this SPF tree, router A will search for the endpoint that is closest (farthest/highest cost from

the origin) to "Dest" that is eligible. Assuming that all LSPs in the above diagram are eligible, LSP

endpoint G will be selected as it terminates on router G while other LSPs only reach routers C and

E, respectively.

IGP and LSP metrics associated with the various LSP are ignores; only tunnel endpoint matters to

IGP. The endpoint that terminates closest to "Dest" (highest IGP path cost) will be selected for

further selection of the LDP over RSVP tunnels to that endpoint. Note that the explicit path the

tunnel takes may not match the IGP path the SPF computes.

51, assume that the user wants to use LDP over RSVP between router A and destination

Link & IGP Cost

7450 ESS MPLS Guide