How Mld Snooping Works - HP FlexFabric 5700 Series Configuration Manual
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Also See for FlexFabric 5700 Series:
- Security configuration manual (460 pages) ,
- Configuration manual (185 pages) ,
- Configuration manual (63 pages)
Table of Contents
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 include 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 on the local subnet to
check for the existence of IPv6 multicast group members.
After receiving an MLD general query from the MLD querier, the switch forwards the query to all ports in
the VLAN except the receiving port. 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. It also 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 from a host, the switch forwards the report through all the router ports in
the VLAN. It also resolves the IPv6 address of the reported IPv6 multicast group, and looks up the
forwarding table for a matching entry:
If no match is found, the switch creates a forwarding entry for the group with the receiving port as
•
an outgoing interface. It also marks the receiving port as a dynamic member port and starts an
aging timer for the port.
If a match is found but the receiving port is not in the forwarding entry, the switch adds the receiving
•
port as an outgoing interface to the forwarding entry. It also marks the receiving port as a dynamic
member port and starts an aging timer for the port.
If a match is found and the receiving port is in the forwarding entry, the switch restarts the aging
•
timer for the port.
In an application with an IPv6 multicast group policy 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
report message, the switch resolves the IPv6 multicast group address in the report and performs ACL
filtering on the report. If the report passes ACL filtering, the switch creates an MLD snooping forwarding
entry for the IPv6 multicast group with the receiving port as an outgoing interface. Otherwise, the switch
drops this report message, which means the receiver does not successfully join the IPv6 multicast group
and cannot retrieve the program.
A switch does not forward an MLD report through a non-router port because of the MLD report
suppression mechanism.
Done message
When a host leaves an IPv6 multicast group, the host sends an MLD done message to the multicast
routers. When the switch receives the MLD done message on a dynamic member port, the switch first
examines whether a forwarding entry matches the IPv6 multicast group address in the message.
ports."
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Troubleshooting
