MLD Snooping Configuration Notes and Feature Limitations

  • Servers (traffic sources) are not required to send Multicast Listening Discovery (MLD) memberships.
  • The default MLD version is V1, where the source address is not sensitive. In this version, (S1,G1) and (S2,G1) would be considered the same group as (*,G1).
  • If MLDv2 is configured on any port of a VLAN, you can check the source information, but because MLD snooping is MAC based, (S,G) switching is not feasible.
  • Hardware resources are installed only when there is data traffic.
  • You can configure the maximum number of groups and the multicast cache (mcache) number.
  • The device supports static groups applying to specific ports. The device acts as a proxy to send MLD reports for the static groups when receiving queries.
  • A user can configure static router ports, forcing all multicast traffic to be sent to these ports.
  • Ruckus devices support fast leave for MLDv1, which stops traffic immediately to any port that has received a leave message.
  • Ruckus devices support tracking and fast leave for MLDv2, which tracks all MLDv2 clients. If the only client on a port leaves, traffic is stopped immediately.
  • An MLD device can be configured as a querier (active) or non-querier (passive). Queriers send queries. Non-queriers listen for queries and forward them to the entire VLAN.
  • Every VLAN can be independently configured as a querier or a non-querier.
  • A VLAN that has a connection to an IPv6 PIM-enabled port on another router should be configured as a non-querier. When multiple snooping devices connect together and there is no connection to IPv6 PIM ports, only one device should be configured as the querier. If multiple devices are configured as active, only one will continue to send queries after the devices have exchanged queries. Refer to MLD snooping-enabled queriers and non-queriers for more information.
  • An MLD device can be configured to rate-limit the forwarding of MLDv1 membership reports to queriers.
  • Because an IPv6 link-local address as the source address when sending queries, a global address is not required.
  • The MLD implementation allows snooping on some VLANs or on all VLANs. MLD can be enabled or disabled independently for each VLAN. In addition, individual ports of a VLAN can be configured as MLDv1 and MLDv2. In general, global configuration commands such as ipv6 multicast.... apply to all VLANs except those with a local multicast... configuration, which supersedes the global configuration. Configuring the version on a port or a VLAN only affects the device sent query version. If the lower version is configured, higher version reports cannot be processed. However, if the higher version is configured lower versions can also be processed.
  • MLD snooping requires hardware resources. If the device has insufficient resources, the data stream without a resource is mirrored to the CPU in addition to being VLAN flooded, which can cause high CPU usage. To avoid this situation, Ruckus recommends that you avoid enabling snooping globally unless necessary.
  • To receive data traffic, MLD snooping requires clients to send membership reports. If a client does not send reports, you must configure a static group to force traffic to client ports.
  • Multicast Router Discovery (MRD) messages are useful for determining which nodes attached to a switch have multicast routing enabled. This capability is useful in a Layer 2 bridge domain with snooping switches. By utilizing MRD messages, Layer 2 switches can determine where to send multicast source data and group membership messages. Multicast source data and group membership reports must be received by all multicast routers on a segment. Using the group membership protocol Query messages to discover multicast routers is insufficient due to query suppression.

Because Ruckus does not support MRD, this can lead to stream loss when non-Querier router ports age out on the Querier after the initial Query election. To avoid such stream loss, configure a static router port on the querier on each interface that connects to a non-querier snooping device.

On the ICX devices, if MLDv2 is configured on any port of a VLAN, you can check the source information, but because MLD snooping is MAC-based, (S,G) switching is not feasible.

MLD/PIMv6 SM snooping over Multi-Chasis Trunking is only supported on Ruckus ICX 7650, and ICX 7850 devices.

Use MLD v2 only in a source-specific application. Because each VLAN can be configured for the version independently, some VLANs might match (* G) while others match (S G)