ZyXEL NBG420N Manuel d'utilisateur télécharger pdf (Page 128)

Chapter 9 LAN

NBG420N User’s Guide

128

9.2.2 IP Address and Subnet Mask

Refer to the IP address and subnet mask section in the Connection Wizard chapter for this

information.

9.2.3 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 Management 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 NBG420N supports both IGMP version 1 (IGMP-v1) and IGMP version 2 (IGMP-v2).

At start up, the NBG420N queries all directly connected networks to gather group

membership. After that, the NBG420N periodically updates this information. IP multicasting

can be enabled/disabled on the NBG420N LAN and/or WAN interfaces in the web

configurator (LAN; WA N). Select None to disable IP multicasting on these interfaces.

9.2.4 Any IP

Traditionally, you must set the IP addresses and the subnet masks of a computer and the

NBG420N to be in the same subnet to allow the computer to access the Internet (through the

NBG420N). In cases where your computer is required to use a static IP address in another

network, you may need to manually configure the network settings of the computer every time

you want to access the Internet via the NBG420N.

With the Any IP feature and NAT enabled, the NBG420N allows a computer to access the

Internet without changing the network settings (such as IP address and subnet mask) of the

computer, when the IP addresses of the computer and the NBG420N are not in the same

subnet. Whether a computer is set to use a dynamic or static (fixed) IP address, you can simply

connect the computer to the NBG420N and access the Internet.

The following figure depicts a scenario where a computer is set to use a static private IP

address in the corporate environment. In a residential house where a NBG420N is installed,

you can still use the computer to access the Internet without changing the network settings,

even when the IP addresses of the computer and the NBG420N are not in the same subnet.

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ZyXEL NBG420N Manuel d'utilisateur Page 128