High availability techniques such as redundancy, FHRP, and SSO ​

First-hop router (FHR) ​

A router that is directly attached to the source, also known as a root router. It is responsible for sending register messages to the RP. A Rendezvous Point (RP) is a router in a multicast network domain that acts as a shared root for a multicast shared tree.

Multicast Routing Information Base (MRIB) ​

A topology table that is also known as the multicast route table (mroute), which derives from the unicast routing table and PIM. MRIB contains the source S,group G, incoming interfaces (IIF), outgoing interfaces (OIFs), and RPF neighbor information for each multicast route as well as other multicast-related information.

Multicast Forwarding Information Base (MFIB) ​

A forwarding table that uses the MRIB to program multicast forwarding information in hardware for faster forwarding.

Last-hop router (LHR) ​

A router that is directly attached to the receivers, also known as a leaf router. It is responsible for sending PIM joins upstream toward the RP or to the source.

Outgoing interface (OIF) ​

Any interface that is used to forward multicast traffic down the tree, also known as the downstream interface.