7. List of Timers and Counters
Most of these timers and counters are configurable. If non-default settings are used, they MUST be consistent among all routers on a single link.
7.1. Robustness Variable
The Robustness Variable allows tuning for the expected packet loss on a network. If a network is expected to be lossy, the Robustness Variable may be increased. MLD is robust to [Robustness Variable] - 1 packet losses.
Default: 2
7.2. Query Interval
The Query Interval is the interval between General Queries sent by the Querier.
Default: 125 seconds
7.3. Query Response Interval
The Maximum Response Delay inserted into the periodic General Queries.
Default: 10000 milliseconds (10 seconds)
7.4. Multicast Address Listening Interval
The amount of time that must pass before a multicast router decides there are no more listeners for a multicast address or a particular source on a network.
Value: ([Robustness Variable] * [Query Interval]) + [Query Response Interval]
7.5. Other Querier Present Interval
The length of time that must pass before a multicast router decides that there is no longer another multicast router which should be the Querier.
Value: ([Robustness Variable] * [Query Interval]) + (0.5 * [Query Response Interval])
7.6. Startup Query Interval
The interval between General Queries sent by a Querier on startup.
Default: 1/4 the [Query Interval]
7.7. Startup Query Count
The number of Queries sent out on startup, separated by the [Startup Query Interval].
Default: [Robustness Variable]
7.8. Last Listener Query Interval
The Maximum Response Delay inserted into Multicast-Address-Specific Queries sent in response to reports indicating a listener is leaving.
Default: 1000 milliseconds (1 second)
7.9. Last Listener Query Count
The number of Multicast-Address-Specific Queries sent before the router assumes there are no local listeners.
Default: [Robustness Variable]
7.10. Unsolicited Report Interval
The time between repetitions of a listener's initial report of interest in a multicast address.
Default: 1 second
7.11. Older Version Querier Present Timeout
The time-out for transitioning a host back to MLDv2 mode once an older version query is heard.
Value: ([Robustness Variable] * [Query Interval]) + [Query Response Interval]