Netopia 2200 - Manual (Page 97)

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Configure
The IP Trap Entry screen appears.
Enter an IP Trap Entr y IP address. This is the destination for SNMP trap messages, the IP
address of the host acting as an SNMP console.
Click the Submit button. Click the Aler t icon, and in the resulting page, click the Save
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 ser vices 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 for warding device, Netopia Routers use a
protocol for for warding 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 por t level for an IGMP
repor t. The switch then processes the IGMP repor t and star ts for warding the relevant mul-
ticast stream onto the host's por t. When the switch receives an IGMP leave message, it
processes the leave message, and if appropriate stops the multicast stream to that par tic-
ular por t. Basically, customer IGMP messages although processed by the switch are also
sent to the multicast routers.