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ZyWALL 2 Series User's Guide
RIP Version controls the format and the broadcasting method of the RIP packets that the ZyWALL 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 send routing data in RIP-2 format; the difference being that RIP-2B uses subnet
broadcasting while RIP-2M uses multicasting. Multicasting can reduce the load on non-router machines
since they generally do not listen to the RIP multicast address and so will not receive the RIP packets.
However, if one router uses multicasting, then all routers on your network must use multicasting, also.
By default, RIP Direction is set to Both and RIP Version to RIP-1.
5.5.3
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. 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 ZyWALL supports both IGMP version 1 (IGMP-v1) and IGMP version 2 (IGMP-v2). At start up, the
ZyWALL queries all directly connected networks to gather group membership. After that, the ZyWALL
periodically updates this information. IP multicasting can be enabled/disabled on the ZyWALL LAN and/or
WAN interfaces in the web configurator (LAN; WAN). Select None to disable IP multicasting on these
interfaces.
5.6
Configuring IP
Click LAN to open the IP screen.
LAN
5-3
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