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44.5.4 IPv6 DCSCM Troubleshooting
IP v6 DCSCM module acts like ACL, so most problems are caused by improper configuration. Please read the
instructions above carefully.
44.6 MLD
44.6.1 Introduction to MLD
MLD (Multicast Listener Discovery) is the multicast group member (receiver) discovery protocol serving IP v6
multicast. It is similar to IGMP Protocol in IP v4 multicast application. Correspondingly, MLD Protocol version1
is similar to IGMP Protocol version2, and MLD Prot ocol version2 is similar to IGMP Protocol version3. Current
firmware
supports MLDv1/ MLDv2.
The IP v6 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 protoc ol if there are receivers of certain
multicast group on the net work 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 members hip report message; the switch periodically sends members hip query message
and determines if there is host joining a specific group in its subnet works 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 prot ocol messages of MLD Protocol, that is, Query, Report and Done (which is
corresponding to Leave of IGMP v2). Like IGMPV 2, 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 IGMP v2.
MLD protocol version2 use FF02::16 as destination address of membership report, and 143 as data type. The
other logic of MLD Protocol version2 is similar to IGMP Protocol version3.
44.6.2 MLD Configuration Task List
1、 Start MLD (Required)
2、 Configure MLD auxiliary parameters (Required)
（1）Configure MLD group paramet ers
1）Configure MLD group filter conditions
（2）Configure MLD query parameters
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Table of Contents
Troubleshooting
