Dynamic Host Configuration Protocol
Dynamic Host Configuration Protocol |
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A group of TCP/IP computers can use a multicast IP address to send directed communication to all computers with which they share the use of the group address. Multicast addresses are shared by many computers.
When the destination address for an IP datagram is a multicast address, the packet is forwarded to all members of that multicast group, which is a set of zero or more computers identified by that multicast address.
Multicast addresses support dynamic membership, allowing individual computers to join or leave the multicast group at any time. Group membership is not limited by size, and computers are not restricted to membership in any single group. In addition, any computer that uses TCP/IP can send datagrams to any multicast group. A multicast group is similar to a group e-mail address in its usage. When an IP multicast address is used as the destination address for an IP datagram, the datagram is forwarded to all members of the multicast group identified by the address.
You can permanently reserve multicast group addresses or temporarily assign and use them. A permanent group is made by permanently reserving a Class D IP address (224.0.0.0 to 239.255.255.255) with the Internet Assigned Numbers Authority (IANA). The reserved address then becomes a well-known address, indicating a specific multicast group that exists regardless of whether group member computers are present on the network. For multicast IP addresses not permanently reserved with the IANA, all Class D addresses that remain unreserved can then be used dynamically to assign and form temporary multicast groups. These temporary groups can exist as long as one or more computers on the network are configured with the group's address and actively share in its use.