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IPv4 - IGMP - Interface - Properties Page - Router Tab

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Applies To: Windows 7, Windows Server 2008 R2

Use this tab to configure IGMP router mode settings on the specified interface.

Note

The controls on this tab are available for configuration only when the IGMP router mode is enabled on the General tab.

Dialog box element Description

Robustness variable

The robustness variable is a way of indicating the lossy nature of the subnet to which this interface is attached. IGMP can recover from lost IGMP packets (robustness variable is set to 1). You should set the robustness variable to a value of 2 or greater. The default robustness variable is 2.

Query interval (seconds)

The query interval is the amount of time, in seconds, between IGMP General Query messages sent by the router (if the router is the querier on this subnet). The default query interval is 125 seconds.

Query response interval (seconds)

The query response interval is the maximum amount of time, in seconds, that the IGMP router waits to receive a response to a General Query message. The default query response interval is 10 seconds and must be less than the query interval.

Last member query interval (milliseconds)

The last member query interval is the amount of time, in milliseconds, that the IGMP router waits to receive a response to a Group-Specific Query message. The last member query interval is also the amount of time, in seconds, between successive Group-Specific Query messages. The default last member query interval is 1 second.

Startup query interval (seconds)

The startup query interval is the amount of time, in seconds, between successive General Query messages sent by a querier during startup. The default startup query interval is ¼ of the query interval.

Startup query count

The startup query count is the number of general query messages sent at startup.

Last member query count

The last member query count is the number of Group-Specific Query messages sent before the router assumes there are no members of the host group being queried on this interface. The default last member query count is 2.

Automatically recalculate defaults

Specifies whether the values in Startup query interval, Startup query count, and Last member query count are calculated automatically based on the following:

  • The startup query interval is ¼ of the value for the query interval.

  • The startup query count is the same value as the robustness variable.

  • The last member query count is the same value as the robustness variable.

Group membership interval (seconds)

Displays the calculated group membership interval. The group membership interval is the number of seconds that must pass before a multicast router determines that there are no more members of a host group on a subnet. The group membership interval is (robustness variable) * (query interval) + (query response interval).

Other querier present interval

Displays the calculated other querier present interval. The other querier present interval is the number of seconds that must pass before a multicast router determines that there is no other multicast router that should be the querier. The other querier present interval is (robustness variable) * (query interval) + (query response interval)/2.

Additional references