Configuring Igmp Query And Response Parameters - 3Com MSR 50 Series Configuration Manual

1124 C 69: IGMP C
HAPTER
Configuring IGMP Query
and Response
Parameters
ONFIGURATION
To do...
Enter public instance IGMP
view or VPN instance IGMP
view
Configure the router to
discard any IGMP message
that does not carry the
Router-Alert option
Enable 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 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.
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
Use the command...
igmp [ vpn-instance
vpn-instance-name ]
require-router-alert
send-router-alert
Use the command...
system-view
interface interface-type
interface-number
igmp require-router-alert
igmp send-router-alert
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.