Which IPv6 multicast address is used for all OSPF routers?

The multicast address used for all OSPF routers in IPv6 is FF02::5. This address is specifically designated for OSPF routing protocol communications with all OSPF routers on a local link. When OSPF routers use this multicast address, they can send OSPF routing updates and other protocol-related information to all OSPF-enabled devices on the same network segment, facilitating efficient routing protocol operations.

In the context of IPv6 multicast addressing, it's important to recognize that each multicast address serves a different purpose, and many are designated for specific protocols. For instance, FF02::6 is reserved for OSPF designated routers, which is a subset of OSPF routers, while FF02::2 addresses are used for all routers on a link, but not exclusively for OSPF communications. Similarly, FF02::9 does not have a relevant role in OSPF. Understanding these distinctions helps in effectively managing routing protocols in IPv6 networks.