Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - MULTICAST ROUTING CONFIGURATION GUIDE 2010-10-07 Configuration Manual page 215

ipv6 mld explicit-tracking
Copyright © 2010, Juniper Networks, Inc.
The router checks the number of hosts that receive traffic from this group or channel.
If the host sending the leave message is the only host, it performs immediate leave for
that group or channel on that interface. The router removes the interface from the
multicast group or channel immediately, without sending out a group or group-source
specific query and waiting for the last member query interval.
If the host sending the leave message is not the only host receiving traffic for that group
or channel, the router removes the host from the list of hosts on that interface, but
keeps the interface in the outgoing interface list for the multicast group or channel. No
group or group-source specific queries are sent.
You can enable MLD explicit host tracking on an interface only if MLD V1 or V2 has been
previously enabled on the interface. Explicit host tracking is not enabled by default when
you enable MLD on the interface. Explicit host tracking cannot be configured on passive
MLD interfaces.
When you enable explicit host tracking on an interface that has a membership state, the
router does not immediately start performing immediate leave. For a maximum of group
membership interval seconds, the router only performs host tracking. Any leave messages
that the router receives during this period receive normal leave processing. Any leave
messages received after this interval has elapsed receive immediate leave processing,
when appropriate.
When explicit host tracking is enabled on an MLD V2 interface, even if a group has to
downgrade to MLD V1 due to the presence of an MLD V1 host, explicit host tracking
continues for that group. To avoid this, you can use the disable-if-mld-v1-detected
keyword. If you select this option, the router turns off explicit host tracking for the group
when MLD V1 host reports are received for the group on that interface. This option does
not have any significance on an interface configured for MLD V1 and is ignored if selected.
If you execute the command on an interface that was previously enabled for
immediate-leave, the configuration is accepted, immediate-leave is turned off and an
appropriate warning message logged. Any attempt to configure immediate-leave on an
interface that has explicit host tracking enabled is rejected and an error message logged.
The following example enables MLD V2 explicit host tracking on interface 3/0.101 with
the default configuration where the router continues to perform explicit host tracking for
MLD V1 groups. To override this default configuration, use the ip mld explicit-tracking
disable-if-mld-v1-detected command.
interface 3/0.101
ip mld version 2
ip mld explicit-tracking
end
Use to set explicit host tracking for MLD interfaces.
To disable explicit host tracking if MLD V1 hosts are detected, use the
disable-if-mld-detected keyword.
Example
Chapter 6: Configuring Multicast Listener Discovery
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