ZyXEL Communications wireless n gigabit netusb router User Manual

 Chapter 17 WAN

NBG4615 User’s Guide

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. 

Multicast Example

In the multicast example above, systems A and D comprise one multicast group. In multicasting, 
the server only needs to send one data stream and this is delivered to systems A and D. 

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. The NBG4615 supports both IGMP version 1 
(IGMP-v1) and IGMP version 2 (IGMP-v2). 

At start up, the NBG4615 queries all directly connected networks to gather group membership. 
After that, the NBG4615 periodically updates this information. IP multicasting can be enabled/
disabled on the NBG4615 LAN and/or WAN interfaces in the Web Configurator (LAN; WAN). Select 
None to disable IP multicasting on these interfaces.

Use this screen to change your NBG4615’s Internet access settings. Click WAN from the 
Configuration menu. The screen differs according to the encapsulation you choose.