3Com Switch 8800 Advanced Software V5 Configuration Guide

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MLD CONFIGURATION
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The term "router" in this document refers to a router in a generic sense or a
Switch 8800 running the MLD protocol.
When configuring MLD, go to the following sections for information you are
interested in:
■ “MLD Overview” on page 637
■ “Configuration Task List” on page 640
■ “Displaying and Maintaining MLD Configuration” on page 645
■ “MLD Configuration Example” on page 646
■ “Troubleshooting MLD” on page 647
MLD Overview
Introduction to MLD Multicast listener discovery protocol (MLD) is used by an IPv6 router or a routing
switch to discover the presence of multicast listeners on directly-attached subnets.
Multicast listeners are nodes wishing to receive multicast packets.
Through MLD, the router can learn whether there are any IPv6 multicast listeners
on directly-connected subnets, put corresponding records in the database, and
maintain timers related to IPv6 multicast addresses.
Routers running MLD use an IPv6 unicast link-local address as the source address
to send MLD messages. MLD messages are Internet control message protocol for
IPv6 (ICMPv6) messages. All MLD messages are confined to the local subnet, with
a hop count of 1.
MLD Version So far, two MLD versions are available:
■ MLDv1 (defined in RFC 2710), which is derived from IGMPv2.
■ MLDv2 (defined in RFC 3810), which is derived from IGMPv3.
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At present, the Switch 8800s support only MLDv1.
How MLDv1 Works MLDv1 implements IPv6 multicast listener management based on the
query/response mechanism.
MLDv1 uses two types of query messages: