Using Ip Multicast - ZyXEL Communications Prestige 2302RL Support Notes

Prestige 2302RL Support Notes

Using IP Multicast

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What is IP Multicast ?
Traditionally, IP packets are transmitted in two ways - unicast or broadcast. Multicast is a third way to
deliver IP packets to a group of hosts. Host groups are identified by class D IP addresses, i.e., those with
"1110" as their higher-order bits. In dotted decimal notation, host group addresses range from 224.0.0.0 to
239.255.255.255. Among them, 224.0.0.1 is assigned to the permanent IP hosts group, and 224.0.0.2 is
assigned to the multicast routers group.
IGMP (Internet Group Management Protocol) is the protocol used for multicasting. There are currently two
versions: versions 1 and 2. Through IGMP, IP hosts are able to report their multicast group membership to any
immediate-neighbor multicast routers which decide if a multicast packet needs to be forwarded.
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