MPLS and RSVP
7450 ESS MPLS Guide Page 157
Procedures at LSR Node
The following procedures occur at an LSR node that is not a branch node:
• The LSR performs a label swapping operation on a leaf of the P2MP LSP. This is a
conventional operation of an LSR in a P2P LSP. An ILM entry is programmed at the
ingress of the LSR to map an incoming label to a NHLFE.
The following is an exception handling procedure for control packets received on an ILM in an
LSR.
• Packets that arrive with the TTL in the outer label expiring are sent to the CPM for further
processing and are not forwarded to the egress NHLFE.
Procedures at Branch LSR Node
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 limit of 127 OIF/NHLFEs per ILM entry.
The following is an exception handling procedure 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.
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