Configuring Igmp Fast Leave Processing - 3Com MSR 50 Series Configuration Manual

1126 C 69: IGMP C
HAPTER
n
c
Configuring IGMP Fast
Leave Processing
ONFIGURATION
To do...
Configure the maximum
response time for IGMP
general queries
Configure the IGMP
last-member query interval
Configure the other querier
present interval
If not statically configured, the other querier present interval is [IGMP
■
robustness variable] times [ IGMP robustness variable ] plus [maximum
response time for IGMP general queries] divided by two. By default, the values
of these three parameters are 60 (seconds), 2 (times) and 10 (seconds)
respectively, so the default value of the other querier present interval = 60 × 2
+ 10 / 2 = 125 (seconds).
If statically configured, the other querier present interval takes the configured
■
value.
CAUTION:
Make sure that the other querier present interval is greater than the IGMP
■
query interval; otherwise the IGMP querier may change frequently on the
network.
Make sure that the IGMP query interval is greater than the maximum response
■
time for IGMP general queries; otherwise, multicast group members may be
wrongly removed.
The configurations of the maximum response time for IGMP general queries,
■
the IGMP last member query interval and the IGMP other querier present
interval are effective only for IGMPv2 or IGMPv3.
In some applications, such as ADSL dial-up networking, only one multicast receiver
host is attached to a port of the IGMP querier. To allow fast response to the leave
messages of the host when it switches frequently from one multicast group to
another, you can enable IGMP fast leave processing on the IGMP querier.
With the fast leave processing enabled, after receiving an IGMP leave message
from a host, the IGMP querier directly sends a leave notification to the upstream
without sending IGMP group-specific queries. Thus, the leave latency is reduced
on one hand, and the network bandwidth is saved on the other hand.
Configuring IGMP fast leave processing globally
Follow these steps to enable IGMP fast leave processing globally:
To do...
Enter system view
Enter public instance IGMP
view or VPN instance IGMP
view
Use the command...
igmp max-response-time
interval
igmp
last-member-query-interval
interval
igmp timer
other-querier-present interval
Use the command...
system-view
igmp [ vpn-instance
vpn-instance-name ]
Description
Optional
10 seconds by default
Optional
1 second by default
Optional
For the system default, see
"Note" below
Description
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