Configuring the Branch LSP as a Dynamic Path

By default, the branch LSP for a point-to-multipoint LSP is signaled dynamically using CSPF and requires no configuration.

When a point-to-multipoint LSP is changed, either by the addition or deletion of new destinations or by the recalculation of the path to existing destinations, certain nodes in the tree might receive data from more than one incoming interface. This can happen under the following conditions:

• Some of the branch LSPs to destinations are statically configured and might intersect with statically or dynamically calculated paths to other destinations.
• When a dynamically calculated path for a branch LSP results in a change of incoming interface for one of the nodes in the network, the older path is not immediately torn down after the new one has been signaled. This ensures that any data in transit relying on the older path can reach its destination. However, network traffic can potentially use either path to reach the destination.
• A faulty router at the ingress calculates the paths to two different branch destinations such that a different incoming interface is chosen for these branch LSPs on a router node common to these branch LSPs.

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