Igmp Querier - Fujitsu XG1200 User Manual

XG1200 User's Guide

4.8.4 IGMP Querier

In a general network configuration, the multicast router periodically sends out an IGMP General Query message to determine if
the hosts on the network are members of any multicast groups by receiving a response from the hosts.
IGMP Querier is a function that acts as a proxy for a multicast router when it is not included in a network segment to send an
IGMP General Query message to all terminals.
The number of Query messages issued is configured using the "ip snooping vlan send-query-count" command.
The frequency at which the General Query messages are sent (query interval) is automatically calculated by the following
equation based the frequency at which the Query messages are sent and the group member interval.
Query interval = (Group membership interval - 10)/send query count (seconds)
The default setting for the Query interval is 125 seconds.
Upon reception of an IGMP Leave message, the XG1200 sends an IGMP Specific Query (GSQ) message to determine that
the host is interested in leaving the group.
If an IGMP Specific Query message is sent as many times as specified by the send query count and a terminal does not
respond with an IGMP Report message, that group is removed.
Generally, IGMP Querier uses "0.0.0.0" for the source IP address when sending a Query message.
Since some client software does not return a response for a Query message with the source IP
address being set to "0.0.0.0", it is recommended that an address other than "0.0.0.0" be used.
If multicast router exists, XG 1200 does not send Query message even if IGMP Querier is valid.
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