As we have learned from previous lesson, IPv4 Class D multicast address range is between 126.96.36.199 and 188.8.131.52. 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 184.108.40.206/8 (220.127.116.11 through 18.104.22.168) 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 22.214.171.124 to 126.96.36.199 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 188.8.131.52 to 184.108.40.206 (220.127.116.11/24) are reserved for local purposes in the local network segment. The routers should not forward IPv4 datagrams addressed to link-local multicast address range 18.104.22.168 to 22.214.171.124 to another network segment. The main use of the link-local multicast address ranges from 126.96.36.199 to 188.8.131.52 is for router discovery and to communicate routing information between routers.
Some important link-local multicast addresses are listed below.
|Link-local multicast address||Description|
|184.108.40.206||All systems on local network segment|
|220.127.116.11||All routers on local network segment|
|18.104.22.168||OSPF designated routers|
|22.214.171.124||DHCP server/relay agent|
|126.96.36.199||All PIM routers|
|188.8.131.52||VRRP (Virtual Router Redundancy Protocol)|
|184.108.40.206||All IGMPv3-capable multicast routers|
|220.127.116.11||HSRP (Hot Standby Router Protocol)|
|18.104.22.168||PTP v2 (Precision Time Protocol)|
|22.214.171.124||mDNS (Multicast DNS)|
|126.96.36.199||LLMNR (Link-local Multicast Name Resolution)|