Configuring MLD Snooping Global Options

A number of MLD snooping options can be configured on Ruckus devices in global configuration mode.

You must configure the MLD mode and version globally before entering these options. See the Configuring the MLD Snooping Mode and Version Globally task.

The following option configurations are outlined in the steps below:

  • Modify the age interval for group membership entries—When the device receives a group membership report, it makes an entry for that group in the MLD group table. The age interval specifies how long the entry can remain in the table before the device receives another group membership report.
  • Modify the query interval (only for MLD active mode)—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.
  • Configure report control (MLD v1 only)—A device in passive mode forwards reports and leave messages from clients to the upstream router ports that are receiving queries. You can configure a report control option to rate-limit report forwarding within the same group to no more than once every 10 seconds. This rate-limiting does not apply to the first report answering a group-specific query.
  • Modify the wait time before stopping traffic when receiving a leave message—You can define the wait time before stopping traffic to a port when a leave message is received. The device sends group-specific queries once per second to ask if any client in the same port still needs this group. Due to internal timer granularity, the actual wait time is between n and (n+1) seconds (n is the configured value).
  • Modify the multicast cache age time—You can set the time for an mcache to age out when it does not receive traffic. The traffic is hardware switched. Two seconds before aging out an mcache, the device mirrors a packet of this mcache to CPU to reset the age. If no data traffic arrives within two seconds, this mcache is deleted. Be aware when using ICX devices and MAC-based MLD snooping is supported, more than one mcache can be mapped to the same destination MAC. As a result, 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.
  • Enable or disable error or warning messages—The device prints error or warning messages when it 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.

The following task steps can be configured in any order and are all optional. Commands that are limited to a specific MLD mode or version are identified in the task step.

  1. Enter global configuration mode.
    device# configure terminal
  2. Modify the age interval, in seconds, for group membership entries.
    device(config)# ipv6 multicast age-interval 280
    When multiple devices are connected together, all devices must have the same age interval configured, 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.
  3. Modify the query interval, in seconds (only for MLD active mode).
    device(config)# ipv6 multicast query-interval 120
    When multiple queriers connect together, they must all be configured with the same query interval.
  4. Configure report control (MLD v1 only).
    device(config)# ipv6 multicast report-control
    MLD v1 membership reports of the same group from different clients are considered to be the same and are rate-limited. This alleviates the report storm caused by multiple clients answering the upstream router query.
    Note: This feature applies to MLD v1 only. The leave messages are not rate limited.
  5. Modify the wait time before stopping traffic when receiving a leave message.
    device(config)# ipv6 multicast leave-wait-time 5
  6. Modify the multicast cache age time.
    device(config)# ipv6 multicast mcache-age 150
    Note: The mcache age value configured may not expire accurately. You may notice a delay of 0 to 60 seconds.
  7. Enable or disable error or warning messages.
    device(config)# ipv6 multicast verbose-off

The following example configures the IPv6 multicast options.

device# configure terminal
device(config)# ipv6 multicast age-interval 280
device(config)# ipv6 multicast query-interval 120
device(config)# ipv6 multicast max-response-time 5
device(config)# ipv6 multicast report-control
device(config)# ipv6 multicast leave-wait-time 5
device(config)# ipv6 multicast mcache-age 150
device(config)# ipv6 multicast verbose-off