User's Manual

ZyAIR B-2000 Wireless LAN Gateway with 4-Port Switch
Internet Access 3-5
3.4 IP 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 is a third way to deliver IP packets to a group
of hosts on the network - not everybody.
IGMP (Internet Group Multicast Protocol) is a session-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 ZyAIR supports both IGMP version 1 (IGMP-v1) and version 2 (IGMP-v2). At start up, the ZyAIR
queries all directly connected networks to gather group membership. After that, the ZyAIR periodically
updates this information. IP Multicasting can be enabled/disabled on the ZyAIR LAN and/or WAN
interfaces using menus 3.2 (LAN) and 11.3 (WAN). Select None to disable IP Multicasting on these
interfaces.
3.5 TCP/IP Ethernet and DHCP Setup
Use menu 3.2 to configure your ZyAIR for TCP/IP.
To edit menu 3.2, enter 3 from the main menu to display Menu 3-Ethernet Setup. When menu 3 appears,
press 2 and press [ENTER] to display Menu 3.2-TCP/IP and DHCP Ethernet Setup, as shown next
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