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Dynamic MLD Configuration Overview

The Multicast Listener Discovery (MLD) Protocol manages the membership of hosts and routers in multicast groups. IP version 6 (IPv6) multicast routers use MLD to learn, for each of their attached physical networks, which groups have interested listeners. Each router maintains a list of host multicast addresses that have listeners for each subnet, as well as a timer for each address. However, the router does not need to know the address of the listeners—just the address of the hosts. The router provides addresses to the multicast routing protocol it uses; this ensures that multicast packets are delivered to all subnets where there are interested listeners. In this way, MLD is used as the transport for the Protocol Independent Multicast (PIM) protocol.

Subscriber access supports the configuration of MLD within the dynamic profiles hierarchy for dynamically created interfaces. By specifying MLD statements within a dynamic profile, you can dynamically apply MLD configuration when a subscriber connects to an interface using a particular access technology (DHCP), enabling the subscriber to access a carrier (multicast) network.

Dynamic MLD consists of a subset of the full range of MLD capabilities available for static MLD configuration, applied to dynamic interfaces by means of a dynamic profile. For detailed information about static MLD configuration, see Configuring MLD. Much of the static configuration documentation is directly applicable to dynamic MLD. Note that the following statements that appear in the dynamic MLD CLI hierarchy are configurable, but have no effect: accounting, group-threshold, log-interval, and no-accounting. These statements are not needed at a subscriber level , where typically no more than tens of joins are expected.

Refer to the Multicast Protocols User Guide for a comprehensive understanding of Junos OS support for multicast protocols.