show cdp neighbors detail
Cause: Radio interference from 2.4 GHz Wi-Fi or microwave ovens.
Fix: Enable "Frequency Hopping" mode via the advanced settings. The 3555 Top firmware supports adaptive hopping across 79 channels.
Possible cause: The IP address of the 3555 Top has been reset to default, or the Ethernet port is faulty. cdp bt serial number 3555 top
Solution:
If you’re on a Cisco switch/router and want to locate a directly connected Cisco device with a specific serial number: show cdp neighbors detail