Which protocol primarily manages multicast group membership?

The protocol that primarily manages multicast group membership is the Internet Group Management Protocol (IGMP). IGMP is used by hosts and adjacent routers on an IP network to establish multicast group memberships. When a device wishes to join a multicast group, it sends an IGMP report to inform the router of its interest in receiving data addressed to that group. Conversely, if a device no longer needs to receive the multicast data, it can send an IGMP leave message. This process allows routers to manage the distribution of multicast traffic efficiently, ensuring that only those devices that wish to receive the multicast traffic are part of the group and reducing unnecessary network load.

Other protocols mentioned, such as BGP, OSPF, and EIGRP, serve different networking purposes. BGP (Border Gateway Protocol) is utilized for routing between autonomous systems on the internet. OSPF (Open Shortest Path First) and EIGRP (Enhanced Interior Gateway Routing Protocol) are used for interior gateway routing within a single autonomous system, focusing on finding the best path for data packets rather than managing multicast group memberships. These protocols do not provide the specific functionality required to manage multicast group memberships, making IGMP the appropriate choice.