User Manual

49-24
Switch(config)#ipv6 multicast destination-control fe80::203:fff:fe01:228a/64 access-group 9000
Thus, the users of this segment can only join groups other than 2ff1e::1/64.
3．Multicast policy
Server 2008::1 is sending important multicast data in group ff1e::1, we can configure on its access switch as
follows:
Switch(config)#ipv6 multicast policy 2008::1/128 ff1e::1/128 cos 4
Thus this multicast flow will have a priority of 4, when it passes the TRUNK port of this switch to another
switch (generally speaking, it is a relatively high priority, the data with higher priority might be protocol data, if
a higher priority is set, when there is too much multicast data, the switch protocol might operate abnormally).
49.5.4 IPv6 DCSCM Troubleshooting
IPv6 DCSCM module acts like ACL, so most problems are caused by improper configuration. Please read the
instructions above carefully.
49.6 MLD
49.6.1 Introduction to MLD
MLD (Multicast Listener Discovery) is the multicast group member (receiver) discovery protocol serving IPv6
multicast. It is similar to IGMP Protocol in IPv4 multicast application. Correspondingly, MLD Protocol version1
is similar to IGMP Protocol version2, and MLD Protocol version2 is similar to IGMP Protocol version3. Current
firmware supports MLDv1/ MLDv2.
The IPv6 multicast hosts can join or leave from multicast group at any location, any time, regardless of the
total number of group members. It is unnecessary and impossible for multicast switch to store the relationship
among all host members. Multicast switch simply finds out via MLD protocol if there are receivers of certain
multicast group on the network segment connected to each port. The only thing host need to do is to keep the
record of which multicast groups it joined.
MLD is unsymmetrical between host and switch: the host needs to respond the MLD query message of
multicast switch with membership report message; the switch periodically sends membership query message
and determines if there is host joining a specific group in its subnetworks according to the response message
received, and after it receives the report of a host quitting from the group, it sends out the query for the group
to confirm if there is no member left in it.
There are three types of protocol messages of MLD Protocol, that is, Query, Report and Done (which is
corresponding to Leave of IGMPv2). Like IGMPV2, the Query messages include General Query and Specific
Group Query. General Query uses the multicast address FF02::1 of hosts as destination address, the group
address is 0; and Specific Group Query use its group address as destination address. The multicast
addresses of MLD use 130, 131 and 132 as data types denoting the three kinds of messages mentioned
above. Other logic is basically same as IGMPv2.