Managing Group Members - Fujitsu XG1200 User Manual

XG1200 User's Guide

4.8.3 Managing Group Members

When network congestion causes Leave message loss or there is a terminal that uses IGMPv1, the multicast router does not
receive Leave messages. The multicast router sends out an IGMP General Query message to all terminals (IP address:
224.0.0.1) at intervals (query interval) to determine membership information.
Upon reception of an IGMP General Query message, a terminal, a member of the group, returns an IGMP Report message to
maintain membership to the group.
In consideration of General Query or Report message loss caused by network congestion, it is recommended that the value
that satisfies the following equation be taken as the group member interval for the XG1200.
Group member interval = (query interval for multicast router) × 2 + 10 (seconds)
Since RFC defines the default query interval for multicast router as 125 seconds, the XG1200 uses 260 seconds for the default
group member interval.
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