The following procedures occur at an LSR node that is a branch node:
The LSR performs a replication and a label swapping for each leaf of the P2MP LSP. An ILM entry is programmed at the ingress of the LSR to map an incoming label to a list of OIF and corresponding NHLFEs.
There is a system defined limit on the number of OIF/NHLFEs per ILM entry.
For control packets received on an ILM in a branch LSR, packets that arrive with the TTL in the outer label expiring are sent to the CPM for further processing and not copied to the LSP branches.