B-4. Well-Known IP Multicast Addresses

Some client server applications use a multicast packet to send large streams of data to many hosts with a single transmission. The multicast packet uses special addressing at Layer 3 and Layer 2 to communicate with clients that have been configured to receive these packets. The multicast packet contains a Class D IP address to specify the group of devices that are to receive the packet. This group is known as the multicast group, and the IP address translates directly to a multicast Ethernet address. The Ethernet multicast address has the first 24 bits set to 01-00-5E, the next bit is set to 0, and the last 23 bits are set to match the low 23 bits of the IP multicast address. Figure B-6 shows how Layer 3 ...

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