Protocol Independent Multicast - Source-Specific Multicast (PIM-SSM) is designed for scenarios where receivers know the specific source address (S) for a multicast group (G) they wish to join. This (S, G) information, typically provided by IGMPv3 from the host, allows the last-hop router to send PIM Join messages directly toward the source. This process builds a shortest-path tree (SPT) from the source to the receivers without the need for source discovery. The Rendezvous Point (RP) is a fundamental component of PIM Sparse Mode (PIM-SM), where it acts as a meeting point for unknown sources and receivers on a shared tree (, G). Since PIM-SSM completely eliminates the concept of a shared tree and the associated source discovery mechanism, the RP has absolutely no function.

A. The PIM routing protocol: PIM is the essential control plane protocol used in SSM to signal (S, G) state and build the source-based distribution trees between routers.

B. SSM translation on access multicast router: This feature, also known as SSM mapping, is specifically used in SSM networks to allow legacy IGMPv1/v2 hosts (which can only signal ,G) to participate by mapping their requests to a pre-configured (S, G) channel.

D. IGMP snooping: This is a Layer 2 mechanism on switches that optimizes multicast traffic delivery within a VLAN. It is essential for efficiency regardless of the PIM mode (SM, DM, or SSM).

E. IGMP Querier: The IGMP Querier is a router function required on every multicast-enabled LAN segment to solicit membership reports from hosts. It is fundamental for the router to learn which multicast groups, including (S, G) channels, are needed.

1. Nokia 7750 SR OS R21.10.R1 MPLS Guide, Section: PIM-SSM: "SSM is an enhancement to the PIM protocol and does not require a separate protocol. It uses the existing PIM protocol messages and procedures. SSM does not use the PIM-SM shared tree and RP." This statement explicitly confirms that the RP is not used in PIM-SSM.

2. RFC 4607: Source-Specific Multicast for IP, Section 3: Protocol Overview: "PIM-SSM is derived from PIM-SM [RFC4601]. It uses the same PIM packet formats and most of the same protocol mechanisms. The primary difference is that PIM-SSM builds a tree from the receiver to the source, and it does not use the PIM-SM shared tree and Rendezvous Point (RP) mechanisms."

3. Nokia 7750 SR OS R21.10.R1 Unicast Routing Protocols Guide, Section: IGMP: This guide details the function of the IGMP Querier and its necessity for soliciting host memberships, a process required for PIM-SSM to learn of receiver interest. It also describes SSM translation for IGMPv1 and IGMPv2 hosts.