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MLD Snooping

MLD (Multicast Listener Discovery) snooping enables a controller, service platform or access point to examine MLD packets and make forwarding decisions based on content. MLD is used by IPv6 devices to discover devices wanting to receive multicast packets destined for specific multicast addresses. MLD uses multicast listener queries and multicast listener reports to identify which multicast addresses have listeners and join multicast groups.

MLD snooping caps the flooding of IPv6 multicast traffic on controller, service platform or access point VLANs. When enabled, MLD messages are examined between hosts and multicast routers and to discern which hosts are receiving multicast group traffic. The controller, service platform or access point then forwards multicast traffic only to those interfaces connected to interested receivers instead of flooding traffic to all interfaces.

To set the MLD Snooping parameters:

  1. Select the MLD Snooping tab.
    Click to expand in new window
    Network Bridge VLAN screen, MLD Snooping tab
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  2. Define the following General MLD snooping parameters for the Bridge VLAN configuration:

    Enable MLD Snooping

    Enable MLD snooping to examine MLD packets and support content forwarding on this Bridge VLAN. Packets delivered are identified by a single multicast group address. Multicast packets are delivered using best-effort reliability, just like IPv6 unicast. MLD snooping is enabled by default.

    Forward Unknown Packets

    Use this option to either enable or disable IPv6 unknown multicast forwarding. This setting is enabled by default.
  3. Define the following Multicast Router settings:

    Interface Names

    Select the ge or radio interfaces used for MLD snooping.

    Multicast Router Learn Mode

    Set the pim-dvmrp or static multicast routing learn mode. DVMRP builds a parent-child database using a constrained multicast model to build a forwarding tree rooted at the source of the multicast packets. Multicast packets are initially flooded down this source tree. If redundant paths are on the source tree, packets are not forwarded along those paths.
  4. Set the following MLD Querier parameters for the profile‘s Bridge VLAN configuration:

    Enable MLD Querier

    Select this option to enable MLD querier on the controller, service platform or access point. When enabled, the device sends query messages to discover which network devices are members of a given multicast group. This setting is enabled by default.

    MLD Version

    Define whether MLD version 1 or 2 is utilized with the MLD querier. MLD version 1 is based on IGMP version 2 for IPv4. MLD version 2 is based on IGMP version 3 for IPv4 and is fully backward compatible. IPv6 multicast uses MLD version 2. The default MLD version is 2.

    Maximum Response Time

    Specify the maximum response time (from 1 - 25,000 milliseconds) before sending a responding report. Queriers use MLD reports to join and leave multicast groups and receive group traffic. The default setting is 1 milliseconds.

    Other Querier Timer Expiry

    Specify an interval in either Seconds (60 - 300) or Minutes (1 - 5) used as a timeout interval for other querier resources. The default setting is 60 seconds.
  5. Click the OK button located at the bottom right of the screen to save the changes.

    Click Reset to revert to the last saved configuration.

Published July 2019prev | next

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