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    Configuring MLD Settings on an Interface

    When you start MLD on an interface, it operates with the default settings. You can, however, modify:

    • The method that the router uses to remove hosts from multicast groups
    • The time interval at which the querier sends multicast listener queries
    • The time that a querier waits before sending a new query to hosts from which it receives multicast listener done messages
    • The time that a non-querier waits for queries from the current querier before sending query messages to assume responsibility of querier
    • The time that a host can take to reply to a query (maximum response time)
    • The number of times that the router sends each MLD message from this interface

    Note: You can configure MLD only on IPv6 interfaces. For information about configuring IPv6 interfaces, see Configuring IPv6 in the JunosE IP, IPv6, and IGP Configuration Guide.

    To configure MLD settings for an interface:

    • Enable the immediate-leave feature.
      host1:boston(config-if)#ipv6 mld immediate-leave

      The router immediately removes a host from a multicast group after receiving a multicast listener done message from the host associated with this interface.

      Use the no version to restore the default behavior, in which the router removes a host from a multicast group if that host does not return a multicast listener report within a certain length of time after receiving a multicast listener query from the router.

      Caution: Issue this command only on MLD interfaces to which one MLD host is connected. If more than one MLD host is connected to a LAN through the same interface, and one host sends a done message, the router removes all hosts on the interface from the multicast group. The router loses contact with the hosts that should remain in the multicast group until they send join requests in response to the router's next general multicast listener query.

      Note: As an alternative method, you can configure the immediate-leave feature using the MLD-Immediate-Leave RADIUS attribute (VSA 26-100) in RADIUS Access-Accept messages. The RADIUS setting takes precedence over a CLI setting. The radius ignore command is used to ignore or accept RADIUS attributes from Access-Accept messages.

    • Configure the last member query interval, which specifies the maximum time the router will wait for a response after sending a last member query. Using a lower value allows members to leave groups more quickly.
      host1:boston(config-if)#ipv6 mld last-member-query-interval 90

      Use the no version to restore the default, 10-tenths of a second (1 second).

    • Configure the time that the interface waits before declaring itself as the querier.
      host1:boston(config-if)#ipv6 mld querier-timeout 200

      Use the no version to set the time to the default, twice the query interval.

    • Configure the query interval, which specifies how often the router sends MLD host-query packets from the interface.
      host1:boston(config-if)#ipv6 mld query-interval 100

      Use the no version to set the polling interval to the default, 125 seconds.

      Note: As an alternative method, you can configure the query interval using the MLD-Query-Interval RADIUS attribute (VSA 26-98) in RADIUS Access-Accept messages. The RADIUS setting takes precedence over a CLI setting. The radius ignore command is used to ignore or accept RADIUS attributes from Access-Accept messages.

    • Configure the maximum response time, which specifies the period during which the host is expected to respond to an MLD query. MLDv1 and MLDv2 include this value in MLD query messages sent out on the interface. Using a lower value allows members to join and leave groups more quickly.
      host1:boston(config-if)#ipv6 mld query-max-response-time 120

      Use the no version to restore the default, 100 tenths of a second (10 seconds).

      Note: As an alternative method, you can configure the query maximum response time using the MLD-Query-Max-Resp-Time RADIUS attribute (VSA 26-99) in RADIUS Access-Accept messages. The RADIUS setting takes precedence over a CLI setting. The radius ignore command is used to ignore or accept RADIUS attributes from Access-Accept messages.

    • Configure the robustness value, which specifies the number of times that the router sends MLD group-specific queries before declaring a group to no longer have any members on the interface.
      host1:boston(config-if)#ipv6 mld robustness 2

      Use the no version to restore the default, 3.

    Published: 2014-08-19