A replication segment is the forwarding instruction for a P2MP LSP. It contains the incoming replication SID and a set of OIFs and their corresponding SID or SID list. A replication segment is identified by a tree ID, root ID, and path instance ID (LSP ID) through the root, transit, and leaf nodes.
A second kind of replication segment is a shared replication segment. A shared replication segment is shared between multiple root nodes or P2MP LSPs. For this reason, it does not have a root ID, but contains a replication segment identifier, which is within the tree ID. A shared replication segment can be used for Fast Reroute (FRR). Currently, the P2MP policy supports a link protection facility bypass FRR.