System information

1. System Concepts
1-6 July 2004 4821-A2-GB21-00
IGMP Snooping
Internet Group Management Protocol (IGMP) snooping is a method of handling
multicast data streams by analyzing IGMP packets to learn multicast group
address and port associations.
The following parameters control IGMP snooping:
 Leave Delay – The amount of time that the multicast stream will continue on a
port after the receipt of a Leave message.
 Leave-Join Forwarding Delay – The amount of time that the start of a new
multicast stream on a port is delayed following the receipt of a leave message.
 Quick Query Wait Time – The amount of time to wait for a reply before
issuing another Quick Query message.
These parameters are set using the CLI or web interface.
Join A Query for A
Leave A
Query for A
Join B
Leave Delay Parameter
Send Join B Send Leave A and Stop Old Stream
Start New Stream
Leave - Join Forwarding Delay ParameterQuick Query Wait Time Parameter
From DSLAM
to Upstream
STB (Set-Top Box)
to/from DSLAM
Stream A
Stream B
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