3Com Switch 4800G 24-Port Configuration Manual page 621

Configuring IGMP Query
and Response
Parameters
By default, for the consideration of compatibility, the device does not check the
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Router-Alert option, namely it processes all the IGMP messages it received. In
this case, IGMP messages are directly passed to the upper layer protocol, no
matter 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.
Configuring IGMP packet options globally
Follow these steps to configure IGMP packet options globally:
To do...
Enter system view
Enter IGMP view
Configure the router to
discard any IGMP message
that does not carry the
Router-Alert option
Enable the insertion of the
Router-Alert option into IGMP
messages
Configuring IGMP packet options on an interface
Follow these steps to configure IGMP packet options on an interface:
To do...
Enter system view
Enter interface view
Configure the interface to
discard any IGMP message
that does not carry the
Router-Alert option
Enable the insertion of the
Router-Alert option into IGMP
messages
The IGMP querier periodically sends IGMP general queries at the "IGMP query
interval" to determine whether any multicast group member exists on the
network. You can tune the IGMP general query interval based on actual condition
of the network.
On startup, the IGMP querier sends "startup query count" IGMP general queries
at the "startup query interval", which is 1/4 of the "IGMP query interval". Upon
receiving an IGMP leave message, the IGMP querier sends "last member query
count" IGMP group-specific queries at the "IGMP last member query interval".
Both startup query count and last member query count are set to the IGMP querier
robustness variable.
Adjusting IGMP Performance
Use the command...
system-view
igmp
require-router-alert
send-router-alert
Use the command...
system-view
interface interface-type
interface-number
igmp require-router-alert
igmp send-router-alert
621
Description
-
-
Optional
By default, the device does
not check the Router-Alert
option.
Optional
By default, IGMP messages
carry the Router-Alert option.
Description
-
-
Optional
By default, the device does
not check the Router-Alert
option.
Optional
By default, IGMP messages
carry the Router-Alert option.