Multicast - ZyXEL Communications P-660RU-T1 v3 User Manual

Chapter 8 LAN Setup
The Version field controls the format and the broadcasting method of the RIP packets that the
ZyXEL Device sends (it recognizes both formats when receiving). RIP-1 is universally
supported; but RIP-2 carries more information. RIP-1 is probably adequate for most networks,
unless you have an unusual network topology.
Both RIP-2B and RIP-2M sends the routing data in RIP-2 format; the difference being that
RIP-2B uses subnet broadcasting while RIP-2M uses multicasting.

8.3.6 Multicast

Traditionally, IP packets are transmitted in one of either two ways - Unicast (1 sender - 1
recipient) or Broadcast (1 sender - everybody on the network). Multicast delivers IP packets to
a group of hosts on the network - not everybody and not just 1.
IGMP (Internet Group Multicast Protocol) is a network-layer protocol used to establish
membership in a Multicast group - it is not used to carry user data. IGMP version 2 (RFC
2236) is an improvement over version 1 (RFC 1112) but IGMP version 1 is still in wide use.
IGMP version 3 supports source filtering, reporting or ignoring traffic from specific source
address to a particular host on the network. If you would like to read more detailed information
about interoperability between IGMP version 2 and version 1, please see sections 4 and 5 of
RFC 2236. The class D IP address is used to identify host groups and can be in the range
224.0.0.0 to 239.255.255.255. The address 224.0.0.0 is not assigned to any group and is used
by IP multicast computers. The address 224.0.0.1 is used for query messages and is assigned
to the permanent group of all IP hosts (including gateways). All hosts must join the 224.0.0.1
group in order to participate in IGMP. The address 224.0.0.2 is assigned to the multicast
routers group.
The ZyXEL Device supports IGMP version 1 (IGMP-v1), IGMP version 2 (IGMP-v2) and
IGMP version 3 (IGMP-v3). At start up, the ZyXEL Device queries all directly connected
networks to gather group membership. After that, the ZyXEL Device periodically updates this
information. IP multicasting can be enabled/disabled on the ZyXEL Device LAN and/or WAN
interfaces in the web configurator (LAN; WAN). Select None to disable IP multicasting on
these interfaces.
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P-660RU-Tx v3 User's Guide