How Mld Snooping Works - HP 6125XLG Configuration Manual

Timer
Dynamic
member port
aging timer
NOTE:
In MLD snooping, only dynamic ports age out. Static ports never age out.

How MLD snooping works

The ports in this section are dynamic ports. For information about how to configure and remove static
ports, see "Configuring static
MLD messages are general query, MLD report, and done message. An MLD snooping-enabled switch
performs differently depending on the MLD message.
General query
The MLD querier periodically sends MLD general queries to all hosts and routers identified by the address
FF02::1 on the local subnet to determine whether any active IPv6 multicast group members exist on the
subnet.
After receiving an MLD general query, the switch forwards the query to all ports in the VLAN except the
port that received the query. The switch also performs one of the following actions:
If the receiving port is a dynamic router port in the router port list, the switch restarts the aging timer
•
for the router port.
If the receiving port does not exist in the router port list, the switch adds the port to the router port
•
list, and starts an aging timer for the port.
MLD report
A host sends an MLD report to the MLD querier for the following purposes:
Responds to queries if the host is an IPv6 multicast group member.
•
• Applies for an IPv6 multicast group membership.
After receiving an MLD report, the switch forwards it through all the router ports in the VLAN, resolves the
IPv6 address of the reported IPv6 multicast group, and performs one of the following actions:
• If no forwarding entry matches the group address, the switch creates a forwarding entry for the
group, adds the receiving port as a dynamic member port to the forwarding entry for the group,
and starts an aging timer for the port.
If a forwarding entry matches the group address, but the receiving port is not in the forwarding
•
entry for the group, the switch adds the port as a dynamic member port to the forwarding entry, and
starts an aging timer for the port.
If a forwarding entry matches the group address and the receiving port is in the forwarding entry
•
for the group, the switch restarts the aging timer for the port.
In an application with an IPv6 multicast group filter configured on an MLD snooping-enabled switch,
when a user requests a multicast program, the user's host initiates an MLD report. After receiving this
Description
When a port dynamically joins a
multicast group, the switch starts or
resets an aging timer for the port.
When the timer expires, the dynamic
member port ages out.
ports."
Message received
before the timer
expires
MLD report message.
101
Action after the timer
expires
The switch removes the
port from the MLD
snooping forwarding
table.