Brocade Communications Systems IPMC5000PEF manual Displaying MLD snooping information

Enabling fast convergence

Enabling fast convergence

In addition to periodically sending general queries, an active (querier) device sends out general queries when it detects a new port. However, since it does not recognize the other device port-up event, the multicast traffic might still use the query-interval time to resume after a topology change. Configuring fast-convergence allows the device to listen to topology change events in Layer 2 protocols, such as spanning tree, and send general queries to shorten the convergence time.

If the Layer 2 protocol is unable to detect a topology change, the fast-convergence feature may not work. For example, if the direct connection between two devices switches from one interface to another, the rapid spanning tree protocol (802.1w) considers this an optimization action, rather than a topology change. In this case, other devices will not receive topology change notifications and will be unable to send queries to speed up the convergence. The original spanning tree protocol does not recognize optimization actions, and fast-convergence works in all cases.

To enable fast-convergence, enter commands such as the following.

device(config)#vlan 70 device(config-vlan-70)#multicast6 fast-convergence

Syntax: [no] multicast6 fast-convergence

Displaying MLD snooping information

You can display the following MLD snooping information:

•MLD snooping error information

•Group and forwarding information for VLANs

•Information about MLD snooping mcache

•MLD memory pool usage

•Status of MLD traffic

•MLD information by VLAN

Displaying MLD snooping error information

To display information about possible MLD errors, enter the following command.

device#show ipv6 multicast error

snoop SW processed pkt: 173, up-time 160 sec

Syntax: show ipv6 multicast error

The following table describes the output from the show ipv6 multicast error command.

Field	Description
SW processed pkt	The number of IPv6 multicast packets processed by MLD snooping.
up-time	The MLD snooping up time.

FastIron Ethernet Switch IP Multicast Configuration Guide	55
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