ZyXEL Communications P-334WHD - Manual (Page 122)

P-334WHD User’s Guide
122 Chapter 8 LAN
Where you obtain your network number depends on your particular situation. If the ISP or
your network administrator assigns you a block of registered IP addresses, follow their
instructions in selecting the IP addresses and the subnet mask.
If the ISP did not explicitly give you an IP network number, then most likely you have a single
user account and the ISP will assign you a dynamic IP address when the connection is
established. The Internet Assigned Number Authority (IANA) reserved this block of addresses
specifically for private use; please do not use any other number unless you are told otherwise.
Let's say you select 192.168.1.0 as the network number; which covers 254 individual
addresses, from 192.168.1.1 to 192.168.1.254 (zero and 255 are reserved). In other words, the
first three numbers specify the network number while the last number identifies an individual
computer on that network.
Once you have decided on the network number, pick an IP address that is easy to remember,
for instance, 192.168.1.1, for your ZyXEL Device, but make sure that no other device on your
network is using that IP address.
The subnet mask specifies the network number portion of an IP address. Your ZyXEL Device
will compute the subnet mask automatically based on the IP address that you entered. You
don't need to change the subnet mask computed by the ZyXEL Device unless you are
instructed to do otherwise.
8.2.3 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 ZyXEL Device supports both IGMP version 1 (IGMP-v1) and IGMP version 2 (IGMP-
v2). 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.