How Mld Snooping Works - HP A5500 SI Switch Series Configuration Manual

Aging timers for dynamic ports and related messages and actions
Timer
Dynamic router port
aging timer
Dynamic member port
aging timer
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 runs 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
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 also 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. The switch also performs the following judgment:
Description
For each dynamic router
port, the switch sets a timer
initialized to the dynamic
router port aging time.
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.
ports."
Message before
expiry
MLD general query of
which the source
address is not 0::0 or
IPv6 PIM hello.
MLD report message.
242
Action after expiry
The switch removes this
port from its router port
list.
The switch removes this
port from the MLD
snooping forwarding
table.