HP 6125XLG R2306-HP 6125XLG Blade Switch IP Multicast Configuration Guide - Page 108

How MLD snooping works, General query, MLD report

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Timer Dynamic member port aging timer 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. Message received before the timer expires MLD report message. NOTE: In MLD snooping, only dynamic ports age out. Static ports never age out. Action after the timer expires The switch removes the port from the MLD snooping forwarding table. 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 ports." 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 101

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101
Timer
Description
Message received
before the timer
expires
Action after the timer
expires
Dynamic
member port
aging timer
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.
MLD report message.
The switch removes the
port from the MLD
snooping forwarding
table.
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 ports
."
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