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894 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Configuring MLD snooping
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The system supports up to 32K of groups. The configurable range is 256 to 32768 and the default
is 8192. The configured number is the upper limit of an expandable database. Client memberships
exceeding the group limits are not processed.
Disabling transmission and receipt of MLD packets on a port
When a VLAN is snooping-enabled, all MLD packets are trapped to the CPU without hardware VLAN
flooding. The CPU can block MLD packets to and from a multicast-disabled port, and will not add
that port to the output interfaces or hardware resources, which prevents the disabled port from
receiving multicast traffic. However, if static groups to the entire VLAN are defined, the traffic for
these groups is flooded to the entire VLAN, including to the disabled ports. Since the hardware
cannot block traffic from disabled ports, hardware traffic is switched in the same way as traffic
from enabled ports.
NOTE
This command has no effect on a VLAN that is not snooping-enabled because all multicast traffic is
VLAN flooded.
PowerConnect(config)#interface ethernet 0/1/3
PowerConnect(config-if-e1000-0/1/3)#ipv6-multicast-disable
Syntax: [no] ipv6-multicast-disable
Configuring the global MLD mode
You can configure a device for either active or passive (default) MLD mode. If you specify an MLD
mode for a VLAN, the MLD mode overrides the global setting:
• Active – In active MLD mode, the device actively sends out MLD queries to identify IPv6
multicast groups on the network, and makes entries in the MLD table based on the group
membership reports it receives from the network.
• Passive – In passive MLD mode, the device forwards reports to the router ports which receive
queries. MLD Snooping in passive mode does not send queries, but does forward queries to
the entire VLAN.
To globally set the MLD mode to active for the device, enter the following command.
PowerConnect(config)#ipv6 mld-snooping active
Syntax: [no] ipv6 mld-snooping [active | passive]
Omitting both the active and passive keywords is the same as entering ipv6 mld-snooping passive.
Modifying the age interval
When the device receives a group membership report, it makes an entry in the MLD group table for
the group in the report. The age interval specifies how long the entry can remain in the table
without the device receiving another group membership report. When multiple devices connect
together, all devices should be configured with the same age interval. The age interval should be at
least twice that of the query interval, so that missing one report will not stop traffic. For a
non-querier, the query interval should equal that of the querier.
To modify the age interval, enter a command such as the following.
PowerConnect(config)#ipv6 mld-snooping age-interval 280