ZyXEL Communications P-660R-11V3 User Manual

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Chapter 8 LAN Setup
P-660R-T1 v3 User’s Guide
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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.