What is solicited-node multicast address?

Solicited-node multicast address is a special type of multicast address that is used in IPv6 network communication to reach a specific group of hosts. It is used by nodes to discover other nodes on the same network segment using the Neighbor Discovery Protocol (NDP).

The solicited-node multicast address is derived from the host's IPv6 address with the prefix FF02::1:FF/104 and the lowest 24 bits of the IPv6 address being used as the interface identifier. Thus, a solicited-node multicast address will be in the range FF02::1:FF00:0000 to FF02::1:FFFF:FFFF, and there can be up to 2^24 or 16,777,216 unique solicit-node multicast addresses.

When a node needs to send a Neighbor Solicitation message to a specific host, it sends the message to the solicited-node multicast address that corresponds to the target host's IPv6 address. This allows the message to be delivered to the intended host and all other hosts that are listening to the same multicast address, without burdening the entire network with unnecessary traffic.

Overall, solicited-node multicast addresses play an important role in ensuring efficient communication and neighbor discovery in IPv6 networks.