At an LSR node which is both a branch node and an egress leaf node (bud node), the bud LSR performs a pop operation on one or many replications of the received packet and a swap operation of the remaining replications. An ILM entry is programmed at ingress of the LSR to map the incoming label to list of NHLFE/OIF and next-hop/OIF. The exact same packets are replicated to an LSP leaf and to a local interface.
The following are the exception handling procedures for control packets received on an ILM in a bud LSR:
Packets which arrive with the TTL in the outer label expiring are sent to the CPM and are not copied to the LSP branches.
Packets whose TTL does not expire are copied to all branches of the LSP. The local copy of the packet is sent to the CPM for further processing if there is any of the IP header exception handling conditions set after the label is popped: 127/8 destination address, router alert option set, or any other options set.