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2
IGMP snooping configuration
The static group drop option discards data traffic to a group in hardware. The group can be any
multicast group including groups in the reserved range of 224.0.0.X. The drop option does not
apply to IGMP packets, which are always trapped to CPU when snooping is enabled. The drop
option applies to the entire VLAN, and cannot be configured for a port list. When the drop option is
not specified, the group must exist outside the reserved range.
Brocade(config-vlan-20)#multicast static-group 239.1.1.1 count 3 drop
Syntax: [no] multicast static-group ipv4-address [count num ] [port-numbers| drop]
The ipv4-address parameter is the address of the multicast group.
The count is optional, which allows a contiguous range of groups. Omitting the count num is
equivalent to the count being 1.
Disabling IGMP snooping on a VLAN
When IGMP snooping is enabled globally, you can still disable it for a specific VLAN. For example,
the following commands cause IGMP snooping to be disabled for VLAN 20. This setting overrides
the global setting.
Brocade(config)#vlan 20
Brocade(config-vlan-20)#multicast disable-multicast-snoop
Syntax: [no] multicast disable-multicast-snoop
Modifying the age interval for group membership entries
When the device receives a group membership report, it makes an entry for that group in the IGMP
group table. The age interval specifies how long the entry can remain in the table before the device
receives another group membership report. When multiple devices connect together, all devices
must be configured for the same age interval, which must be at least twice the length of the query
interval, so that missing one report won't stop traffic. Non-querier age intervals must be the same
as the age interval of the querier.
To modify the age interval, enter the following command.
Brocade(config)#ip multicast age-interval 280
Syntax: [no] ip multicast age-interval interval
The interval parameter specifies the aging time. You can specify a value from 20 through 26000
seconds. The default is 260 seconds.
Modifying the query interval (active IGMP snooping
mode only)
If IP multicast traffic reduction is set to active mode, you can modify the query interval to specify
how often the device sends general queries. When multiple queriers connect together, they must
all be configured with the same query interval.
To modify the query interval, enter the following command.
Brocade(config)#ip multicast query-interval 120
36 FastIron Ethernet Switch IP Multicast Configuration Guide
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