D-Link DGS-6600 Series, Руководство пользователя

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DGS-6604 ip igmp robustness-variable
CLI Reference Guide
271
ip igmp robustness-variable
Use this command to tune for the expected packet loss on a network, i.e. the
Robustness Variable of IGMP.
ip igmp robustness-variable VALUE
Default
VALUE : 2
Command Mode
VLAN Interface configuration
Usage Guideline
This command is valid for the VLAN interface only. Use this command to modify
the IGMP Robustness Variable on an interface.
The IGMP Robustness Variable determines the number of general queries that
IGMP sends before aging out a multicast address when there is no IGMP report
response. In other words, this variable is also used as "last member query
count". The group membership interval is equal to query-interval* robu
max response time.
The larger the Robustness Variable is set, the higher IGMP protocol packet loss
is acceptable. IGMP can recover from robustness variable minus 1 lost IGMP
packet.
Example
This example shows how to configure IGMP Robustness Variable value. It
configures IGMP Robustness Variable value to 5 on interface VLAN 1000.
Verify the settings by entering the show ip igmp interface command.
Syntax Description
VALUE Provides fine-tuning to allow for expected packet loss on a subnet. The value of
the robustness variable is used in calculating the following IGMP message
intervals:
• Group membership interval - Amount of time that must pass before a
multicast router decides there are no more members of a group on a net-
work. This interval is calculated as follows: (robustness variable * query
interval) + (1 * query response interval).
• Other querier present interval - Amount of time that must pass before a
multicast router decides that there is no longer another multicast router
that is the querier. This interval is calculated as follows: (robustness vari-
able * query interval) + (0.5 * query response interval).
• Last member query count - Number of group-specific queries or group-
source-specific (with IGMP Version 3) query messages sent before the
router assumes there are no local members of a group. The default num-
ber is the value of the robustness variable.
The robustness variable range is from 1 to 7.
Switch# configure terminal
Switch(config)# interface vlan1000
Switch(config-if)# ip igmp robustness-variable 5
Switch(config-if)# end