Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

MLD snooping policy configuration and assignment

Updated: April 17, 2026

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Describes the process of implementing MLD snooping functionality by configuring a policy and assigning it to bridge domains.

MLD snooping policy configuration and assignment is a network management process that implements MLD snooping functionality by configuring an MLD snooping policy and then assigning that policy to one or more bridge domains.

Configure an MLD snooping policy using the GUI

Create an MLD snooping policy that provides centralized configuration of MLD snooping settings that can be applied to multiple bridge domains within a tenant.

Use this procedure when you need to establish MLD snooping capabilities across bridge domains in your network infrastructure. The policy defines parameters such as query intervals, fast leave behavior, and querier functionality that control how multicast traffic is managed.

Procedure

Click the Tenants tab and the name of the tenant on whose bridge domain you intend to configure MLD snooping support.
In the Navigation pane, click Policies > Protocol > MLD Snoop.
Right-click MLD Snoop and select Create MLD Snoop Policy.
In the Create MLD Snoop Policy dialog, configure a policy as follows:
1. In the Name and Description fields, enter a policy name and optional description.
2. In the Admin State field, select Enabled or Disabled to enable or disable this entire policy.
  
  The default entry for this field is Disabled.
3. In the Control field, select or unselect Fast Leave to enable or disable MLD v1 immediate dropping of queries through this policy.
4. In the Control field, select or unselect Enable querier to enable or disable the MLD querier activity through the MLD Snoop Policy.
  
  Note
  
  For this option to be effectively enabled, you must enable Querier in the MLD Snoop Policy of the bridge domains to which this policy is applied. The navigation path to the properties page on which this setting is located is Tenants > tenant_name > Networking > Bridge Domains > bridge_domain_name > MLD Snoop Policy.
5. Specify in seconds the Query Interval value for this policy.
  
  The Query Interval is the interval between general queries sent by the querier. The default entry for this fields is 125 seconds.
6. Specify in seconds Query Response Interval value for this policy.
  
  When a host receives the query packet, it starts counting to a random value, less than the maximum response time. When this timer expires, the host replies with a report.
  
  This is used to control the maximum response time for hosts to answer an MLD query message. Configuring a value less than 10 seconds enables the router to prune groups much faster, but this action results in network burstiness because hosts are restricted to a shorter response time period.
7. Specify in seconds the Last Member Query Interval value for this policy.
  
  MLD uses this value when it receives an MLD Leave report. This means that at least one host wants to leave the group. After it receives the Leave report, it checks that the interface is not configured for MLD Fast Leave and, if not, it sends out an out-of-sequence query.
  
  If no reports are received in the interval, the group state is deleted. The software can detect the loss of the last member of a group or source more quickly when the values are smaller. Values range from 1 to 25 seconds. The default is 1 second.
8. Specify the Start Query Count value for this policy.
  
  Number of queries sent at startup that are separated by the startup query interval. Values range from 1 to 10. The default is 2.
9. Specify in seconds a Start Query Interval for this policy.
  
  By default, this interval is shorter than the query interval so that the software can establish the group state as quickly as possible. Values range from 1 to 18,000 seconds. The default is 31 seconds.
Click Submit.

The new MLD Snoop policy is listed in the Protocol Policies - MLD Snoop summary page.

What to do next

To put this policy into effect, assign it to any bridge domain.

Assign an MLD snooping policy to a bridge domain using the GUI

Assigning an MLD Snooping policy to a bridge domain configures that bridge domain to use the MLD Snooping properties specified in that policy.

This task enables you to control multicast traffic forwarding behavior by applying predefined MLD snooping configurations to bridge domains within a tenant.

Before you begin

Configure a bridge domain for a tenant.
Configure the MLD Snooping policy that will be attached to the bridge domain.

Note

For the Enable Querier option on the assigned policy to be effectively enabled, the Subnet Control: Querier IP setting must also be enabled in the subnets assigned to the bridge domains to which this policy is applied. The navigation path to the properties page on which this setting is located is Tenants > tenant_name > Networking > Bridge Domains > bridge_domain_name > Subnets > bd_subnet.

Follow these steps to assign an MLD snooping policy to a bridge domain using the GUI:

Procedure

Click the APIC Tenants tab and select the name of the tenant whose bridge domains you intend to configure with an MLD Snoop policy.
In the APIC navigation pane, click Networking > Bridge Domains, then select the bridge domain to which you intend to apply your policy-specified MLD Snoop configuration.
On the main Policy tab, scroll down to the MLD Snoop Policy field and select the appropriate MLD policy from the drop-down menu.
Click Submit.

The target bridge domain is now associated with the specified MLD Snooping policy.
To configure the node forwarding parameter for Layer 3 unknown IPv6 Multicast destinations for the bridge domain:
1. Select the bridge domain that you just configured.
2. Click the Policy tab, then click the General sub-tab.
3. In the IPv6 L3 Unknown Multicast field, select either Flood or Optimized Flood.
To change the Link-Local IPv6 address for the switch-querier feature:
1. Select the bridge domain that you just configured.
2. Click the Policy tab, then click the L3 Configurations sub-tab.
3. In the Link-local IPv6 Address field, enter a Link-Local IPv6 address, if necessary.
  
  The default Link-Local IPv6 address for the bridge domain is internally generated. Configure a different Link-Local IPv6 address for the bridge domain in this field, if necessary.

The bridge domain is now configured with the MLD snooping policy and any additional IPv6 multicast forwarding or Link-Local address settings you specified.

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