Multicast; Configuring Lan; Figure 23 Lan: Lan - ZyXEL Communications ZyWall P1 User Manual

4.3.4 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.

4.4 Configuring LAN

Click LAN to open the LAN screen.

Figure 23 LAN: LAN

Chapter 4 LAN Screens
ZyWALL P1 User's Guide
75