# Flushing the IGMP router tables and configuring IGMP router alert

Use the following procedure to flush the IGMP router tables. You can also configure the router alert option and query interval on a VLAN.

| Important
| The QueryInterval, Robustness, and Version values must be the same as those configured on the interface (VLAN) of the multicast router (IGMP querier).

| Important
| To maximize your network performance, Avaya recommends that you configure the router alert parameter according to the version of IGMP currently in use: IGMPv1 - Disable IGMPv2 - Enable IGMPv3 - Enable

## Procedure steps

1. From the navigation tree, double-click IP Routing.

2. In the IP Routing tree, double-click IGMP.

3. In the work area, click the Interface tab.

4. In the table, double-click the cell under the FlushAction column heading.

5. Select the desired flush option to flush the routing table.

6. In the toolbar, click Apply.

## Variable definitions

The following table describes the fields of the Interface tab.

Field | Description
--- | ---
IfIndex | Indicates the interface on which IGMP is enabled.
QueryInterval | Indicates the frequency (in seconds) at which IGMP host query packets are transmitted on the interface. Ensure that the robustness value is the same as the configured value on the multicast router (IGMP querier). The range is from 1–65535, and the default is 125.
Status | Indicates whether the interface is active. The interface becomes active if IGMP forwarding ports exist on the interface. If the VLAN has no port members or if all of the port members are disabled, the status is notInService.
Version | Indicates the version of IGMP (1, 2, or 3) configured on this interface. For IGMP to function correctly, all routers on a LAN must use the same version. The default is version 2.
OperVersion | Indicates the version of IGMP currently running on this interface.
Querier | Indicates the address of the IGMP querier on the IP subnet to which this interface attaches.
QueryMaxResponseTime | Indicates the maximum response time (in 1/10 seconds) advertised in IGMPv2 general queries on this interface. This field is a read-only field on the Ethernet Routing Switch 5000 Series .
WrongVersionQueries | Indicates the number of queries received with an IGMP version that does not match the interface. All routers on a LAN must run the same version of IGMP. If queries are received with the wrong version, it indicates a version mismatch.
Joins | Indicates the number of times a group membership is added on this interface; that is, the number of times an entry for this interface is added to the cache table. This number gives an indication of the amount of IGMP activity over time.
Robustness | Specifies tuning for the expected packet loss of a network. This value is equal to the number of expected query packet losses for each serial query interval, plus 1. If you expect a network to lose query packets, you must increase the robustness value. Ensure that the robustness value is the same as the configured value on the multicast router (IGMP querier). The range is from 2 to 255, and the default is 2. The default value of 2 means that one query for each query interval can be dropped without the querier aging out.
LastMembQueryIntvl | Configures the maximum response time (in tenths of a second) that is inserted into group-specific queries sent in response to leave group messages. This parameter is also the time between group-specific query messages. You cannot configure this value for IGMPv1. Decreasing the value reduces the time to detect the loss of the last member of a group. The range is from 0–255, and the default is 10 tenths of seconds. Avaya recommends that you configure this parameter to values higher than 3. If a fast leave process is not required, Avaya recommends values above 10. (The value 3 is equal to 0.3 of a second, and 10 is equal to 1.0 second.)
RouterAlertEnable | When enabled, this parameter instructs the router to ignore IGMP packets that do not contain the router alert IP option. When disabled (default setting), the router processes IGMP packets regardless of whether the router alert IP option is set or not. To maximize your network performance, Avaya recommends that you configure this parameter according to the version of IGMP currently in use: IGMPv1—Disable IGMPv2—Enable IGMPv3—Enable
SendQuery | Indicates whether to send query.
FlushAction | Flushes the specified table type: none flushGrpMem: group member table flushMrouter: mrouter table