Routers are detected based on the TTL of received traffic on the wired side.
The detection would be typically from a Broadcast/Multicast Packet (like DHCP)
Typically, this would mean that there is a L3 AP.
If this is a Valid AP (Aruba AP in this case), there should not be any concern;
But if there are non-valid APs, this would mean that there is a L3 AP deployed;
- If it is of a concern you would have to locate the AP (manually or using the location tracking functionality with ArubaOS) and see if this is a Un-authorized Device.