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MPLS-TE.Ask about CSPF

In constrained based routing.

When there is a request with a required BW.What steps will happen??

1.The CSPF will calculate the route again? Then insert the first route it finds to the routing table.Then its time for the LDP.

2.Or I'm wrong??

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Re: MPLS-TE.Ask about CSPF


LDP plays no role in MPLS Traffic Engineering.

An MPLS TE LSP is setup by using RSVP with TE extensions.

CSPF builds a topology that is aware of current usage level (RSVP resources) used on each link for each direction. (reservations are unidrectional)

The first node sends an RSVP message to the next router to the destination of the tunnel.

Note that the destination can only be the MPLS TE Router-ID of the destination PE node.

In CSPF each node is associated with a single IPv4 address.

So the first router, the headend, builds an RSVP message (PAth) with the required specs BW and sends out of a link that has enough resources to allocate the request. The next router will do the same until to reach the destination node (if reachable). If everything is ok another set of messages are sent hop to hop back to the headend to perform the real resources reservations RSVP (RESV). (RSVP is receveir focused)

hope to help


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