IPv4 link-local multicast addresses

As we have learned from previous lesson, IPv4 Class D multicast address range is between 224.0.0.0 and 239.255.255.255. Four most-significant bits of left-most octet is reserved as 1110 followed by the 28-bit multicast group ID.

The Class D multicast addresses in the range of 224.0.0.0/8 (224.0.0.0 through 224.0.0.255) is the link-local multicast address range of addresses.

There are many reservations for IPv4 multicast addresses for different functions. IPv4 multicast addresses in the range 224.0.0.0 to 224.0.0.255 are called as link-local multicast address range and they are reserved for network protocols on a local network segment. The link-local multicast address range IPv4 multicast address range 224.0.0.0 to 224.0.0.255 (224.0.0.0/24) are reserved for local purposes in the local network segment. The routers should not forward IPv4 datagrams addressed to link-local multicast address range 224.0.0.0 to 224.0.0.255 to another network segment. The main use of the link-local multicast address ranges from 224.0.0.0 to 224.0.0.255 is for router discovery and to communicate routing information between routers.

Some important link-local multicast addresses are listed below.