Igmp (Internet Group Management Protocol) - Netopia 2200 series Software User's Manual

Configure
The IP Trap Entry screen appears.
Enter an IP Trap Entry IP address. This is the destination for SNMP trap messages, the IP
address of the host acting as an SNMP console.
Submit Save
Click the button. Click the Alert icon, and in the resulting page, click the
and Restart
link.
Link:

IGMP (Internet Group Management Protocol)

Multicasting is a method for transmitting large amounts of information to many, but not all,
computers over an internet. One common use is to distribute real time voice, video, and
data services to the set of computers which have joined a distributed conference. Other
uses include: updating the address books of mobile computer users in the field or sending
out company newsletters to a distribution list.
Since a router should not be used as a passive forwarding device, Netopia Routers use a
protocol for forwarding multicasting: Internet Group Management Protocol (IGMP). Netopia
Routers can use either IGMP Version 1 or Version 2.
IGMP "Snooping" is a feature of Ethernet layer 2 switches that "listens in" on the IGMP
conversation between computers and multicast routers. Through this process, it builds a
database of where the multicast routers reside by noting IGMP general queries used in the
querier selection process and by listening to other router protocols.
From the host point of view, the snooping function listens at a port level for an IGMP
report. The switch then processes the IGMP report and starts forwarding the relevant mul-
ticast stream onto the host's port. When the switch receives an IGMP leave message, it
processes the leave message, and if appropriate stops the multicast stream to that partic-
ular port. Basically, customer IGMP messages although processed by the switch are also
sent to the multicast routers.
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