Configuring MLD Fast Leave
Context
In some scenarios such as ADSL dial-up access, a Multicast Listener Discovery (MLD) querier interface connects to only one receiver host. If the host frequently switches between multiple multicast groups, for example, selecting TV channels, you can configure the fast leave function on the interface so that the interface can quickly respond to Multicast Listener Done messages sent from the host.
After fast leave is configured, the querier does not send a Multicast Address Specific Query message or Multicast Address and Source Specific Query message after receiving a Multicast Listener Done message. Instead, the querier directly notifies the upstream multicast device that the host has left the multicast group. The fast leave function reduces delay in response to Done messages and saves network bandwidth.
To limit the range of multicast groups that member hosts can leave fast, configure an IPv6 access control list (ACL6) to define the range of multicast groups and then reference this ACL6. For details about the ACL6 configuration, see "ACL Configuration" in the NetEngine AR Configuration Guide - Security.
Procedure
- Run system-view
The system view is displayed.
- Run interface interface-type interface-number
The interface view is displayed.
- Run mld prompt-leave [ group-policy { acl6-number | acl6-name acl6-name } ]
Fast leave is configured on the interface.
By default, the router sends Multicast Address Specific Query messages or Multicast Address and Source Specific Query messages after receiving a Done message.
When configuring an ACL6 rule for the interface, use the permit parameter to allow the hosts connected to the interface to quickly leave multicast groups with addresses in a specified range. If no rule is configured in the ACL6, hosts connected to the interface cannot quickly leave any multicast groups.
