Wireless Controller
Dedicated Wi-Fi control and management for high density and mobility
rmittal
Staff
Staff
Article Id 197823
Description
The AP 1020e has been configured for L2 preferred and on the same subnet as controller.  However, the connectivity layer shows L3 when the AP comes online on the controller.

In the traces and discovery logs, and by the AP CLI it can be seen that the AP sends L2 discovery frames but that they do not reach the controller, however, the L3 discovery frames do reach controller and hence APs connectivity layer shows as L3.

Scope
Controller - All
AP - 1020e

Solution
In the course of troubleshooting it was found that the AP switch port had STP enabled, and by the time it could go into forwarding state, the AP had already sent out L2 discovery frames, which were obviously dropped as switch port is not in forwarding state.  By the time switch port goes to forwarding state the AP starts L3 discovery frames which are being forwarded and responded by controller.

Conclusion:

It is not recommended to enable STP for AP switch ports as AP is a edge device just like a laptop or desktop.  It does not form a loop.

It is always recommended to have STP disabled for AP switch ports.

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