Download Avaya Configuring IP Multicasting and Multimedia Services User's Manual

Multicasting and Multimedia Overview
Multicast Addresses
Each host group is assigned a unique multicast address. To reach all members of
the group, a sender uses the multicast address as the destination address of the
datagram.
An IP Version 4 multicast address is a Class D address (the high-order bits are set
to 1110) from 224.0.0.0 through 239.255.255.255.
The block of addresses from 224.0.0.1 through 224.0.0.255 is reserved for routing
protocols and other low-level protocols. Multicast routers will not forward
datagrams with addresses in this range.
Internet Group Management Protocol
The Internet Group Management Protocol (IGMP) has the following
characteristics:
•
Allows a host to register group memberships with the local queries router to
receive any datagrams sent to this router and targeted to a group with a
specific IP multicast address.
•
Allows a router to learn the existence of group members on its directly
attached networks. The router periodically sends a general group query
message to each of its local networks. Any host that is a member of a
multicast group identifies itself by sending a response.
For instructions on configuring IGMP, see Chapter 3, “Configuring and
Customizing IGMP.”
Distance Vector Multicast Routing Protocol
The Distance Vector Multicast Routing Protocol (DVMRP) advertises
shortest-path routes to multicasting source networks -- that is, any network
containing hosts that can issue multicast datagrams. (In this respect, DVMRP is
the opposite of RIP, which advertises routes to destination networks.)
For instructions on customizing DVMRP, see Chapter 4, “Customizing DVMRP.”
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