MLD snooping

Multicast Listener Discovery (MLD) snooping performs a similar function for IPv6 as IGMP snooping does for IPv4. With MLD snooping turned on, the switch creates a list of ports that receive multicast data. The switch then only forwards this data to those ports, which avoids flooding all ports on the VLAN.

Global settings

To configure MLD snooping, do as follows:

1. For Status, select Turned on or Turned off to turn on or off MLD snooping on the switch. The default setting is Turned off.
2. For Report Suppression, enter the report suppression value. The report suppression feature limits the number of membership reports the member sends to multicast-capable routers. The default value is 5. The range is from 1 to 25.
3. Click Apply.

VLAN settings

Use the MLD snooping VLAN Settings to configure MLD snooping settings for VLANs on the system. The switch performs MLD snooping on VLANs that send MLD packets. You can specify the VLANs on which IGMP snooping should be performed.

To configure IGMP snooping for VLANs, do as follows:

1. Click Edit next to the VLAN you want to configure.
2. Select On or Off for MLD snooping status from the drop-down list.
3. Select the Version from the drop-down list.
4. Select On or Off for Fast leave.
5. Click Apply.

If the fast leave feature isn't used, a multicast querier will send a GS-query message when receiving an MLD group leave message. The querier only stops forwarding traffic for that group if no endpoint replies to the query within the specified timeout period. If fast leave is turned on, the switch considers the port to have only one endpoint attached. Therefore, fast leave should only be turned on on a port if connected to only one MLD-enabled device.

Fast leave does not apply to a port if the switch has learned that a multicast querier is attached. Fast leave can improve bandwidth usage for a network that frequently experiences many MLD host add and leave requests.

Querier settings

The MLD snooping querier supports MLD snooping in a VLAN where PIM and MLD aren't configured because the multicast traffic doesn't need routing.

The multicast router acts as the MLD querier in networks configured with IP multicast routing. If the IP multicast traffic in a VLAN only needs Layer 2 switching, an IP multicast router isn't required, but without an IP multicast router on the VLAN, another switch must be configured as the MLD querier.

When turned on, the MLD snooping querier sends out MLD queries, which trigger MLD report messages from connected switches that want to receive IP multicast traffic. MLD snooping uses these reports to establish correct forwarding.

You can turn on the MLD snooping querier for all switches in the VLAN, but for every VLAN connected to switches using MLD, you must configure at least one as the MLD snooping querier.

A switch can be configured to generate MLD queries on a VLAN regardless of whether or not IP multicast routing is turned on.

To configure querier settings, do as follows:

1. Click Edit next to the VLAN you want to configure.
2. For Querier status, select On or Off from the drop-down list.
3. For Interval, enter the time in seconds between general query transmissions. The default is 125 seconds.
4. Click Apply.

Group list

The Group list shows the VLAN ID, Group IPv6 address, and member port in the MLD snooping List.

Router settings

The router settings feature shows the learned multicast router attached port if the port is active and a member of the VLAN. Select the VLAN ID you want to configure and enter the static and forbidden ports for the specified VLAN IDs utilizing MLD snooping. All MLD packets snooped by the switch will be forwarded to the multicast router that's reachable from the port.

Click Apply.