H3C Technologies H3C S3100V2 Series Switches - Manual (Page 68)

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Aging timers for dynamic ports in MLD snooping
Table 8 Aging timers for dynamic ports in MLD snooping and related messages and actions
Timer Description
Message before
expiry
Action after expiry
Dynamic router port
aging timer
For each dynamic router
port, the switch sets a timer
initialized to the dynamic
router port aging time.
MLD general query of
which the source address
is not 0::0 or IPv6 PIM
hello.
The switch removes this
port from its router port
list.
Dynamic member port
aging timer
When a port dynamically
joins an IPv6 multicast
group, the switch sets a
timer for the port, which is
initialized to the dynamic
member port aging time.
MLD report message.
The switch removes this
port from the MLD
snooping forwarding
table.
NOTE:
The port aging mechanism of MLD snooping works only for dynamic ports; a static port will never age out.
How MLD snooping works
A switch that is running MLD snooping performs different actions when it receives different MLD
messages.
NOTE:
The description about adding or deleting a port in this section is only for a dynamic port. Static ports can
be added or deleted only through the corresponding configurations. For more information, see
“
Configuring static ports .”
General queries
The MLD querier periodically sends MLD general queries to all hosts and routers—FF02::1—on the local
subnet to determine whether IPv6 multicast group members exist on the subnet.
After receiving an MLD general query, the switch forwards it through all ports in the VLAN except the port
that received the MLD query. The switch performs the following judgment:
• If the port that received the MLD query is a dynamic router port in its router port list, the switch resets
the aging timer for this dynamic router port.
• If the port is not included in its router port list, the switch adds it into its router port list as a dynamic
router port and sets an aging timer for it.
Membership reports
A host sends an MLD report to the MLD querier in the following circumstances:
• If the host has been a member of an IPv6 multicast group, after receiving an MLD query, the host
responds with an MLD report.
• If the host wants to join an IPv6 multicast group, the host sends an MLD report to the MLD querier
to announce that it is interested in the multicast information addressed to that IPv6 multicast group.
After receiving an MLD report, the switch forwards it through all the router ports in the VLAN, resolves the
address of the reported IPv6 multicast group, and performs the following to the receiving port: