H3C Technologies H3C S10500 Series Switches - Manual (Page 123)

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• Determine the maximum response time for IGMP general queries
• Determine the IGMP last-member query interval
• Determine the other querier present interval
Configuring IGMP message options
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 switch does not verify the Router-Alert option
but processes all the IGMP messages that it received. In this case, IGMP messages are directly
passed to the upper-layer protocol, whether or not the IGMP messages carry the Router-Alert option.
• To enhance the switch performance and avoid unnecessary costs, and also for the consideration of
protocol security, you can configure the switch to discard IGMP messages that do not carry the
Router-Alert option.
Configuring IGMP packet options globally
Follow these steps to configure IGMP packet options globally:
To do... Use the command... Remarks
Enter system view system-view —
Enter public network IGMP view or
VPN instance IGMP view igmp [ vpn-instance
vpn-instance-name ]
—
Configure the router to discard any
IGMP message that does not carry
the Router-Alert option
require-router-alert
Required
By default, the switch does not
check the Router-Alert option.
Enable insertion of the Router-Alert
option into IGMP messages
send-router-alert
Required
By default, IGMP messages carry
the Router-Alert option.
Configuring IGMP packet options on an interface
Follow these steps to configure IGMP packet options on an interface:
To do... Use the command... Remarks
Enter system view system-view —
Enter interface view
interface interface-type
interface-number
—
Configure the interface to discard
any IGMP message that does not
carry the Router-Alert option
igmp require-router-alert
Required
By default, the switch does not
check the Router-Alert option.