Multicast Addressing

Because networking devices talk to each other with both Layer 3 and Layer 2 addresses, multicasting must address both these issues. There must be a Layer 3 destination address that the multicast server can use to send out its traffic feed to any participating end stations. There also must be a Layer 2 address that NICs can use to correctly process the information. Within IP, Class D addresses have been reserved for Layer 3 addressing.

With Class D addresses, the first four high-order bits are 1110, providing addresses ranging from 224.0.0.0 through 239.255.255.255. To provide a Layer 2 MAC address, part of the corresponding ...

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