How CSPF Works
The process that generates a path for a TE tunnel to take is different from the regular SPF process, but not much. There are two major differences between regular SPF, done by routing protocols, and CSPF, run by MPLS Traffic Engineering.
For one thing, the path determination process is not designed to find the best route to all routers—only to the tunnel endpoint. This makes the SPF algorithm slightly different: You stop as soon as the node you're trying to get to is on the PATH list, rather than trying to calculate the shortest path to all nodes.
Also, there's now more than one metric at each node. Instead of just a single cost for a link between two neighbors, there's also
Bandwidth
Link attributes
Administrative weight
So how ...
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