Chapter 16
| Multicast Filtering
Layer 2 IGMP (Snooping and Query)
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message received from a downstream host in report and leave messages
sent upstream from the multicast router port.
◆ Interface Version – Sets the protocol version for compatibility with other
devices on the network. This is the IGMP Version the switch uses to send
snooping reports. (Range: 1-3; Default: 2)
This attribute configures the IGMP report/query version used by IGMP
snooping. Versions 1 - 3 are all supported, and versions 2 and 3 are backward
compatible, so the switch can operate with other devices, regardless of the
snooping version employed.
◆ Query Interval – The interval between sending IGMP general queries.
(Range: 2-31744 seconds; Default: 125 seconds)
An IGMP general query message is sent by the switch at the interval specified
by this attribute. When this message is received by downstream hosts, all
receivers build an IGMP report for the multicast groups they have joined.
This attribute applies when the switch is serving as the querier (page 470), or as
a proxy host when IGMP snooping proxy reporting is enabled (page 470).
◆ Query Response Interval – The maximum time the system waits for a
response to general queries. (Range: 10-31744 tenths of a second; Default: 10
seconds)
This attribute applies when the switch is serving as the querier (page 470), or as
a proxy host when IGMP snooping proxy reporting is enabled (page 470).
◆ Last Member Query Interval – The interval to wait for a response to a group-
specific or group-and-source-specific query message. (Range: 1-31740 tenths
of a second in multiples of 10;
Default: 1 second)
When a multicast host leaves a group, it sends an IGMP leave message. When
the leave message is received by the switch, it checks to see if this host is the
last to leave the group by sending out an IGMP group-specific query message,
and starts a timer. If no reports are received before the timer expires, the group
record is deleted, and a report is sent to the upstream multicast router.
A reduced value will result in reduced time to detect the loss of the last
member of a group or source, but may generate more burst traffic.
This attribute will take effect only if IGMP snooping proxy reporting is enabled
(see page 470) or IGMP querier is enabled (page 470).
◆ Last Member Query Count – The number of IGMP proxy group-specific or
group-and-source-specific query messages that are sent out before the system
assumes there are no more local members. (Range: 1-255; Default: 2)
This attribute will take effect only if IGMP snooping proxy reporting or IGMP
querier is enabled.
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