
114064 Rev. A 1-1
Chapter 1
Multicasting Overview
The following sections describe IP multicasting concepts and terminology.
• Multicast Host Groups -- page 1-1
• Multicast Addresses -- page 1-2
• Multicast Protocols -- page 1-3
Group Membership Protocols -- page 1-3
Routing Protocols -- page 1-3
Multicast Host Groups
IP multicasting is a method for addressing, routing, and delivering a datagram to a
collection of receivers -- called a host group.
Host groups can be permanent or transient.
•Apermanent host group has a well-known, administratively assigned IP
multicast group address. It is the address, not the membership, that is
permanent and defines the group. A permanent host group can consist of zero
or more members.
•Atransient host group exists only as long as it has members that need its
services. IP addresses in the multicast range that are not reserved for
permanent groups are available for dynamic assignment to transient host
groups.
Any host system on any IP network can send a message to a multicast group using
the group’s IP multicast address. To receive a message addressed to a multicast
group, however, the host must be a member of the group and must reside on a
network where that group is registered with a local multicast router.
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