HP FlexNetwork NJ5000, User Manual

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whether a forwarding entry matches the IPv6 group address in the message, and, if a match is found,
determines whether the forwarding entry contains the dynamic member port.
•
If no forwarding entry matches the IPv6 multicast group address, or if the forwarding entry does
not contain the port, the switch directly discards the MLD done message.
•
If a forwarding entry matches the IPv6 multicast group address and contains the port, the switch
forwards the MLD done message to all router ports in the VLAN. Because the switch does not
know whether any other hosts attached to the port are still listening to that IPv6 multicast group
address, the switch does not immediately remove the port from the forwarding entry for that
group. Instead, the switch resets the aging timer for that port.
After receiving the MLD done message, the MLD querier resolves the IPv6 multicast group address
in the message and sends an MLD multicast-address-specific query to that IPv6 multicast group
through the port that received the MLD done message. After receiving the MLD
multicast-address-specific query, the switch forwards it through all its router ports in the VLAN and all
member ports for that IPv6 multicast group. The switch also performs one of the following actions for
the port that received the MLD done message:
•
If the port (assuming that it is a dynamic member port) receives any MLD report in response to
the MLD multicast-address-specific query before its aging timer expires, it means that some
host attached to the port is receiving or expecting to receive IPv6 multicast data for that IPv6
multicast group. The switch resets the aging timer for the port.
•
If the port receives no MLD report in response to the MLD multicast-address-specific query
before its aging timer expires, it means that no hosts attached to the port are still monitoring that
IPv6 multicast group address. The switch removes the port from the forwarding entry for the
IPv6 multicast group when the aging timer expires.
Protocols and standards
RFC 4541,
Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener
Discovery (MLD) Snooping Switches
Recommended configuration procedure
Step Remarks
1.
Enabling MLD snooping
globally
Required.
Disabled by default.
2.
Enabling dropping unknown
IPv6 multicast data globally
Optional.
Unknown IPv6 multicast data
refers to IPv6 multicast data for which no
forwarding entries exist in the forwarding table. When the switch
receives such IPv6 multicast traffic, one of the following situations
occurs:
•
If dropping unknown IPv6 multicast data is disabled, the switch
floods unknown IPv6 multicast data in the VLAN.
•
If dropping unknown IPv6 multicast data is enabled, the switch
drops all received unknown IPv6 multicast data.
Disabled by default.
Enable MLD snooping globally before you enable dropping unknown
IPv6 multicast data globally.