Configuration Guide User guide

FastIron Configuration Guide 1619
53-1002494-02
MLD snooping configuration
Modifying the multicast cache (mcache) aging time
You can set the time for an mcache to age out when it does not receive traffic. Two seconds before
an mcache is aged out, the device mirrors a packet of the mcache to the CPU to reset the age. If no
data traffic arrives within two seconds, the mcache is deleted. Note that in FESX and FSX devices,
more than one mcache can be mapped to the same destination MAC. Hence, when an mcache
entry is deleted, the MAC entry may not be deleted. If you configure a lower value, the resource
consumed by idle streams is quickly removed, but packets are mirrored to the CPU more frequently.
Configure a higher value only when data streams are arriving consistently.
You can use the show ipv6 mld-snooping mcache command to view the currently configured
mcache age. Refer to “Displaying MLD snooping mcache information” on page 1625.
To modify the multicast cache age out time, enter the ipv6 mld-snooping mcache-age <num>
command.
Brocade(config)#ipv6 mld-snooping mcache-age 180
Syntax: [no] ipv6 mld-snooping mcache-age <num>
where <num> is a value from 60 to 3600 seconds, and the default is 60 seconds.
Disabling error and warning messages
Error or warning messages are printed when the device runs out of software resources or when it
receives packets with the wrong checksum or groups. These messages are rate limited. You can
turn off these messages by entering the ipv6 mld-snooping verbose-off command.
Brocade(config)#ipv6 mld-snooping verbose-off
Syntax: [no] ipv6 mld-snooping verbose-off
Configuring the MLD mode for a VLAN
You can configure a VLAN for either the active or passive (default) MLD mode. The VLAN setting
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 router ports that receive
queries. MLD snooping in the passive mode does not send queries. However, it does forward
queries to the entire VLAN.
To set the MLD mode for VLAN 20 to active, enter the following commands.
Brocade(config)#vlan 20
Brocade(config-vlan-20)#mld-snooping active
Syntax: [no] mld-snooping active | passive
The default mode is passive.