H3C Technologies H3C SecPath F1000-E - Manual (Page 46)

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To do... Use the command... Remarks
Enter public network IGMP view igmp —
Configure the router to discard any
IGMP message that does not carry
the Router-Alert option
require-router-alert
Optional
By default, the device does not
check the Router-Alert option.
Enable insertion of the Router-Alert
option into IGMP messages
send-router-alert
Optional
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
Optional
By default, the device does not
check the Router-Alert option.
Enable insertion of the Router-Alert
option into IGMP messages
igmp send-router-alert
Optional
By default, IGMP messages carry
the Router-Alert option.
Configuring IGMP Query and Response Parameters
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”.
The IGMP querier periodically sends IGMP general queries at the “IGMP general 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.
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”. IGMP is robust to “robustness variable
minus 1” packet losses on a network. Therefore, a greater value of the robustness variable makes the
IGMP querier “more robust”, but results in a longer multicast group timeout time.
Upon receiving an IGMP query (general query or group-specific query), a host starts a delay timer for
each multicast group it has joined. This timer is initialized to a random value in the range of 0 to the
maximum response time, which is derived from the Max Response Time field in the IGMP query. When
the timer value comes down to 0, the host sends an IGMP report to the corresponding multicast group.
An appropriate setting of the maximum response time for IGMP queries allows hosts to respond to
queries quickly and avoids bursts of IGMP traffic on the network caused by reports simultaneously sent
by a large number of hosts when the corresponding timers expires simultaneously.
• For IGMP general queries, you can configure the maximum response time to fill their Max Response
time field.