ZyXEL Communications 2108 Series Manual

IP Multicasting
(IGMP Snooping)
Ethernet Switch
ZyNOS 3.7
Support Notes
Version 3.70
August 2006

IGMPSupport Note
2
IP Multicasting
How to setup IGMP snooping in your switch?
Figure 1: IGMP and IGMP snooping
IGMP snooping is designed for application with deployment of multicast traffic.
It operates on the underlying IGMP mechanism where a layer two switch
passively listens to the IGMP Query, Report and Leave (IGMP version 2)
packets transmitted between the IGMP router and clients, and collects passing
IGMP messages. Also, the switch records the message’s group registration
information and configures multicasting information accordingly. If the
multicast group information is unknown (not recorded on the switch), the
switch discards that multicast traffic. Only the registered clients that join the
group will receive multicast stream from the IGMP router. Thus this
significantly reduces the multicast traffic forwarded down to the clients.
Another advantage of IGMP snooping is that it allows the intermediate
switches to learn multicast group information without the need of configuring
them manually.
All contents copyright (c) 2006 ZyXEL Communications Corporation.

IGMPSupport Note
3
Configuration of IGMP snooping using web
In this example, we enable the IGMP function on the GS-4024 device (or it has
to be a ZyXEL L3 Switch) and connect it to a multimedia server. Also, we
enable IGMP snooping function on the ES-3124 Switch or other ZyXEL L2
Switch which support IGMP Snooping to connect to the multimedia clients.
Figure 2: IGMP snooping Example
Step one: In the GS-4024 GUI, click the IP Application ÆIGMP. Here, both
versions of the the IGMP function can be enabled ( IGMP-v1 and IGMP-v2). At
this case, we enabled IGMPv2 for both IP Domain.
Figure 3: IGMP Setup
All contents copyright (c) 2006 ZyXEL Communications Corporation.

IGMPSupport Note
4
Step two:In the L2 Switch GUI, click Advanced Application ÆMulticast
and then click Multicast Setting to get to the Multicast Setting page.
Figure 4: IGMP Snooping Setup
Step three: enable IGMP snooping function using the Web-GUI.
All contents copyright (c) 2006 ZyXEL Communications Corporation.

IGMPSupport Note
5
All contents copyright (c) 2006 ZyXEL Communications Corporation.