H3C Technologies H3C SecPath F1000-E - Manual (Page 612)

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NOTE:
This configuration takes effect in dynamically joined multicast groups but not in the statically configured
multicast groups.
Adjusting IGMP performance
For the configuration tasks described in this section:
• In IGMP view, the configuration is effective on all interfaces. In interface view, the configuration is
effective on only the current interface.
• If the same feature is configured in both IGMP view and interface view, the configuration in
interface view is given priority, regardless of the configuration sequence.
Configuration prerequisites
Before adjusting IGMP performance, complete the following tasks:
• Configure any unicast routing protocol so that all devices in the domain are interoperable at the
network layer.
• Configure basic functions of IGMP.
• Determine the startup query interval.
• Determine the startup query count.
• Determine the IGMP general query interval.
• Determine the IGMP querier’s robustness variable.
• Determine the maximum response time for IGMP general queries.
• Determine the IGMP last-member query interval.
• Determine the other querier present interval.
Configuring Router-Alert option of IGMP messages
IGMP queries include group-specific queries and group-and-source-specific queries, and multicast
groups change dynamically, so a device cannot maintain the information for all multicast sources and
groups. For this reason, when an IGMP router receives a multicast packet but cannot locate the outgoing
interface for the destination multicast group, it must use the Router-Alert option to pass the multicast
packet to the upper-layer protocol for processing. For more information about the Router-Alert option, see
RFC 2113.
An IGMP message is processed differently depending on whether it carries the Router-Alert option in the
IP header:
• By default, for the consideration of compatibility, the device does not verify the Router-Alert option.
It processes all the IGMP messages that it received. In this case, IGMP messages are directly passed
to the upper layer protocol, whether the IGMP messages carry the Router-Alert option or not.
• To enhance the device performance and avoid unnecessary costs, and also for the consideration of
protocol security, you can configure the device to discard IGMP messages that do not carry the
Router-Alert option.
To configure IGMP packet options globally:
Step Command Remarks
1. Enter system view. system-view N/A