TCP/IP Tutorial and Technical Overview - IBM Redbooks

Note the following fields in the IPv6 header of the message:
Next 58 (for the following ICMPv6 message header).
Hops Always set to 1.
Source address A link-local source address is used.
In the MLD message itself, notice:
Type There are three types of MLD messages:
130 Multicast Listener Query
366 TCP/IP Tutorial and Technical Overview
There are two types of queries:
– General query: Used to find which multicast
addresses are being listened for on a link.
– Multicast-address-specific query: Used to find if
any nodes are listening for a specific multicast
address on a link.
131 Multicast listener report
Used by a node to report that it is listening to a
multicast address.
132 Multicast listener done
Used by a node to report that it is ceasing to listen to a
multicast address.
Code Set to 0 by sender and ignored by receivers.
Max response delay This sets the maximum allowed delay before a
responding report must be sent. This parameter is only
valid in query messages. Increasing this parameter can
prevent sudden bursts of high traffic if there a lot of
responders on a network.
Multicast address In a query message, this field is set to zero for a general
query, or set to the specific IPv6 multicast address for a
multicast-address-specific query.
In a response or done message, this field contains the
multicast address being listened for.
A router uses MLD to learn which multicast addresses are being listened for on
each of its attached links. The router only needs to know that nodes listening for
a particular address are present on a link; it does not need to know the unicast
address of those listening nodes, or how many listening nodes are present.