- sending ip packets to a group of hosts in the network, RFC 2236 Internet Group Management Protocol v2
- delivery of IP datagramms to multiple hosts using a single destination address
- dynamic membership to groups, clients can dynamicly join groups
- supports all size of groups
single group address for registred applications, that means multiple applications can stream to a single group address
Addressing
Address range:
Multicast uses Class D
224.0.0.0 – 239.255.255.255
Well-known Addresses:
- 224.0.0.1 All hosts on a subnet
- 224.0.0.2 All routers on a subnet
- 224.0.0.4 All distance vector multicast routing protocol routers
- 224.0.0.5 All OSPF routers
- 224.0.0.6 All OSPF designated routers
- 224.0.0.9 All RIP designated routers
- 224.0.0.10 IGRP router
- 224.0.0.13 All Protocl independent Multicast (PIM) routers
To configure a router supporting PIM, the cisco way of supporting multicast, you have to enable ip multicast-routing