ZyXEL Communications XGS-4526 User Manual

XGS-4526/4528F/4728F User’s Guide

This chapter shows you how to configure various multicast features. 

Traditionally, IP packets are transmitted in one of either two ways - Unicast (1 
sender to 1 recipient) or Broadcast (1 sender to everybody on the network). 
Multicast delivers IP packets to just a group of hosts on the network. 

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. Refer 
to RFC 1112, RFC 2236 and RFC 3376 for information on IGMP versions 1, 2 and 3 
respectively.

In IPv4, a multicast address allows a device to send packets to a specific group of 
hosts (multicast group) in a different subnetwork. A multicast IP address 
represents a traffic receiving group, not individual receiving devices. IP addresses 
in the Class D range (224.0.0.0 to 239.255.255.255) are used for IP multicasting. 
Certain IP multicast numbers are reserved by IANA for special purposes (see the 
IANA website for more information). 

With the IGMP filtering feature, you can control which IGMP groups a subscriber 
on a port can join. This allows you to control the distribution of multicast services 
(such as content information distribution) based on service plans and types of 
subscription. 

You can set the Switch to filter the multicast group join reports on a per-port basis 
by configuring an IGMP filtering profile and associating the profile to a port.