Robustness Variable
The robustness variable is a way of indicating how susceptible the subnet is to lost packets. IGMP can recover from robustness variable minus 1 lost IGMP packets. You can also click the scroll arrows to select a new setting. The robustness variable should be set to a value of 2 or greater. The default robustness variable value is 2.
Query Interval
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
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 query response interval is the Maximum Response Time field in the IGMP v2 Host Membership Query message header. The default query response interval is 10 seconds and must be less than the query interval.
Last Member Query Interval
The last member query interval is the amount of time in seconds 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
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 one-fourth of the value for the query interval.
Startup Query Count
The startup query count is the number of general query messages sent at startup. The default startup query count is 2.
Last Member Query Count
The last member query count is the number of Group-Specific Query messages sent before the router assumes that there are no members of the host group being queried on this interface. The default last member query count is 2.
Enable Automatic Recalculation of 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 one-fourth 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
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 calculated as the (robustness variable) * (query interval) + (query response interval). The group membership interval is a calculated value and is not configurable.
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 takes precedence as the querier. The other querier present interval is the robustness variable multiplied by the query interval plus the query response interval divided by two. The other querier present interval is a calculated value and is not configurable.
Reference:
http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/intwork/inaf_mul_nuid.mspx?pf=true
