Multicast

1) Hardware/Ethernet Multicasting

A unicast would have this bit set to ZERO (0), whereas a multicast would be set to ONE (1).

the destination MAC address 01-00-5E-00-00-05 is not the MAC address of a particular host-computer but the MAC address that can be recognized by computers that are part of the multicast group.








2) IP Multicasting





IP Multicast uses Class D IP Adresses:.

224.0.0.5 OSPFIGP OSPFIGP All Routers [RFC2328,JXM1].














3) Mapping IP Multicast to Ethernet Multicast

Internet Group Management Protocol (IGMP)

IGMP is used to dynamically register individual hosts in a multicast group on a particular LAN. Hosts identify group memberships by sending IGMP messages to their local multicast router. Under IGMP, routers listen to IGMP messages and periodically send out queries to discover which groups are active or inactive on a particular subnet.