IGMP snooping parameters of an S series switch

The following IGMP snooping parameters are provided:
- Query-interval: specifies the interval for sending General Query messages. The system starts an aging timer for a member port when the port receives a Report message. The aging time is calculated using the following formula:
Aging time = Robust variable x Query interval + Maximum response time for General Query messages
On the S series modular switch, the default value is 60s. On S and E series fixed switches excluding the S1700, the default value is 125s.
- Max-response-time: specifies the maximum response time for a Query message. After receiving a Query message, a device must send a response message within the specified time. The device may send the Report message at any time before the maximum response time expires. The default interval is 10s.
- Robust-count: specifies the IGMP robustness variable. This parameter is set based on the link performance. If a link is unstable and many packets are discarded, increase the robustness variable. The default robustness variable is 2.
- Last-member-query-interval: specifies the interval for sending Last Member Query messages. In IGMPv2 and IGMPv3, the system starts an aging timer for a member port when the port receives a Leave message. The aging time is calculated using the following formula:
Aging time = Robust variable x Interval for sending Last Member Query messages
The default interval is 1s.
If the IGMP snooping querier is not configured, the parameter is used to calculate the aging time of member ports.
- After a member port receives a Report message from the downstream host, the aging time is as follows:
Aging time = Robust variable x Query interval + Maximum response time for General Query messages
- After a member port receives a Leave message from the downstream host, the aging time is as follows:
Aging time = Robust variable x Interval for sending Last Member Query messages
Run the display igmp-snooping command to check parameter settings on an S series switch excluding the S1700.

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