C9800-VLAN Group

在AireOS的环境下，如果我们想让一个WLAN对应多个VLAN，通常来说，大家的选择可能是通过interface Group的方式来实现WLAN和多个VLAN的对应。而在C9800的环境下，不再是接口和WLAN绑定的概念，在C9800上，是在Policy Profile中配置需要的VLAN。

 但是，在使用VLAN Group，需要注意相关的限制，尤其是在FlexConnect的使用场景！如下是相关限制。

Restrictions for VLAN Groups

• If the number of VLANs in a VLAN group exceeds 32, the mobility functionality might not work as expected and Layer 2 multicast might break for some VLANs. Therefore, it is the responsibility of network administrators to configure a feasible number of VLANs in a VLAN group.

  For the VLAN Groups feature to work as expected, the VLANs mapped in a group must be present in the controller.

• The VLAN Groups feature works for access points in local mode.

• The VLAN Groups feature works only in central switching mode and it cannot be used in FlexConnect local switching mode.

• ARP Broadcast feature is not supported on VLAN groups.

• VLAN group Multicast with VLAN group is only supported in local mode AP. Multicast VLAN is required when VLAN group is configured and uses multicast traffic.

• While you configure VLAN groups with multiple VLANs and each VLAN is used by a different subnet, clients having static IP addresses might be assigned to a wrong VLAN if SVIs are not present on the controller. Hence, for every VLAN that belongs to the VLAN group, ensure that you configure an SVI interface with a valid IP address.