HP 6125G HP 6125G & 6125G/XG Blade Switches IP Multicast Configuration - Page 272

MLD state, Receiver host state listening, MLD messages, MLD query message

Page 272 highlights

When MLDv2 is running on the hosts and routers, Host B can explicitly express its interest in the IPv6 multicast data that Source 1 sends to G (denoted as (S1, G)), rather than the IPv6 multicast data that Source 2 sends to G (denoted as (S2, G)). Thus, only IPv6 multicast data from Source 1 will be delivered to Host B. MLD state A multicast router that is running MLDv2 maintains the multicast address state per multicast address per attached subnet. The multicast address state consists of the following information: • Filter mode-The router keeps tracing the Include or Exclude state. • List of sources-The router keeps tracing the newly added or deleted IPv6 multicast source. • Timers-Filter timers, including the time that the router waits before switching to the Include mode after an IPv6 multicast address times out, the source timer for source recording, and so on. Receiver host state listening By listening to the state of receiver hosts, a multicast router running MLDv2 records and maintains information of hosts joining the source group on the attached subnet. MLD messages The following descriptions are based on MLDv2 messages. MLD query message An MLD querier learns the multicast listening state of neighbor interfaces by sending MLD query messages. The dark area in Figure 74 shows the MLDv1 message format. 261

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When MLDv2 is running on the hosts and routers, Host B can explicitly express its interest in the IPv6
multicast data that Source 1 sends to G (denoted as (S1, G)), rather than the IPv6 multicast data that
Source 2 sends to G (denoted as (S2, G)). Thus, only IPv6 multicast data from Source 1 will be delivered
to Host B.
MLD state
A multicast router that is running MLDv2 maintains the multicast address state per multicast address per
attached subnet. The multicast address state consists of the following information:
Filter mode
—The router keeps tracing the Include or Exclude state.
List of sources
—The router keeps tracing the newly added or deleted IPv6 multicast source.
Timers
—Filter timers, including the time that the router waits before switching to the Include mode
after an IPv6 multicast address times out, the source timer for source recording, and so on.
Receiver host state listening
By listening to the state of receiver hosts, a multicast router running MLDv2 records and maintains
information of hosts joining the source group on the attached subnet.
MLD messages
The following descriptions are based on MLDv2 messages.
MLD query message
An MLD querier learns the multicast listening state of neighbor interfaces by sending MLD query
messages. The dark area in
Figure 74
shows the MLDv1 message format.