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XG Series User's Guide Chapter 4 Switch Functions and their Configuration
IGMP Snooping
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4.8.4 IGMP Querier
In a typical network configuration, the multicast router periodically sends out an IGMP General Query message to
determine if any of the hosts on the network are members of any multicast groups. Receiving a response from a host
ascertains its membership in a multicast group.
IGMP Querier is a function that acts as a proxy for a multicast router when one is not available in a network segment to
send an IGMP General Query message to all hosts.
The Query interval is 126 seconds.
Upon reception of an IGMP Leave message, the device 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 2 times and the host does not respond with an IGMP Report message, that host
is removed.
Note
• 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 a multicast router exists on the network segment, the device does not send Query message even if IGMP
Querier is valid.
XG
IGMP Querier
Terminal 1
Port 1 Port 2 Port 3
IGMP General Query
MAC : 0100.5E01.0001
Destination IP : 224.0.0.1
Group IP : 0.0.0.0
IGMP General Query
MAC : 0100.5E01.0001
Destination IP : 224.0.0.1
Group IP : 0.0.0.0
IGMP Querier
Multicast Server
Terminal 2 Terminal 3