# Configuring unknown multicast filtering

The default switch behavior is to flood all packets with unknown multicast addresses.

Use the following procedure to prevent the flooding of packets with unknown multicast addresses, and enable the forwarding of these packets to static mrouter ports only.

## Procedure steps

1. From the navigation tree, double-click VLAN.

2. In the VLAN tree, double-click VLANs.

3. In the work area, click the Unknown Multicast Filtering tab.

4. Select the UnknownMulticastNoFlood check box to enable unknown multicast flooding.

5. In the toolbar, click Apply.

## Variable definitions

The following table describes the fields of the Unknown Multicast Filtering tab.

Field | Definition
--- | ---
Id | Indicates the VLAN ID.
UnknownMulticastNoFlood | Enables or disables unknown multicast flooding.