Product and Software: This article applies to all Aruba MUX controllers and ArubaOS 2.5.x and 3.3.x.
Configuration and Symptom
The customer has a master-local structure: the master controller is an Aruba 6000, the local controllers are Aruba 2400-E MUX, and all APs terminate on the master controller. After an upgrade from ArubaOS 2.5.x to 3.3.x, some clients fail to connect to certain APs. The same clients work properly with some other APs.
The "bad" APs connect to the local controller MUX port with the MUX feature enabled.
Technically, when the MUX feature is enabled, a GRE tunnel is established between the MUX port and master controller. The MUX port normally is used to connect to wired clients.
If an AP connects to a MUX port, it builds another GRE tunnel with the master controller, so there are two layer GRE tunnels. This process was supported in 2.5.x code for some reason, but it is not supported in ArubaOS 3.3.x, because it is not efficient.
The key here is that the "good" APs are connecting to the master controller directly.
Disable the MUX feature on the ports to which the APs are connecting, and the problem will probably be resolved.
To help isolate the problem, collect detailed information from the "good" and "bad" APs, including the physical connection diagram, and compare them.