H3C Technologies H3C SecPath F1000-E - Manual (Page 926)

901
Adjusting MLD performance
NOTE:
•
In MLD view, the configuration is effective globally. In interface view, the configuration is effective on
only the current interface.
• If the same function or parameter is configured in both MLD view and interface view, the configuration
performed in interface view is given priority, regardless of the configuration sequence.
Configuration prerequisites
Before adjusting MLD performance, complete the following tasks:
• Enable IPv6 forwarding and configure an IPv6 unicast routing protocol so that all devices in the
domain can be interoperable at the network layer.
• Configure basic functions of MLD.
• Determine the startup query interval.
• Determine the startup query count.
• Determine the MLD query interval.
• Determine the MLD querier’s robustness variable.
• Determine the maximum response delay of MLD general query messages.
• Determine the MLD last listener query interval.
• Determine the MLD other querier present interval.
Configuring Router-Alert option for MLD messages
MLD queries include multicast-address-specific queries and multicast-address-and-source-specific queries,
and IPv6 multicast groups change dynamically, so a device cannot maintain the information for all IPv6
multicast sources and groups. Therefore, a router might receive IPv6 multicast packets addressed to IPv6
multicast groups that have no members on the local subnet. In this case, the Router-Alert option carried
in the IPv6 multicast packets is useful for the router to determine whether to deliver the IPv6 multicast
packets to the upper-layer protocol for processing. For more information about the Router-Alert option,
see RFC 2113.
An MLD message is processed differently depending on whether it carries the Router-Alert option in the
IPv6 header, as follows:
• By default, in consideration of compatibility, the device does not check the Router-Alert option. That
is, it processes all received MLD messages. In this case, the device passes MLD messages to the
upper layer protocol for processing, whether the MLD messages carry the Router-Alert option or not.
• To enhance the device performance, avoid unnecessary costs, and ensure protocol security, you
can configure the device to discard MLD messages that do not carry the Router-Alert option.