The beacon can be turned on by either pressing the UID button on the switch front panel, or by using the CLI. The blue beacon on the front panel is a button labeled UID, and on the back panel it is a LED labeled. These port LEDs, as a group or individually, display information about the switch and about the individual ports. Turn on the first one and the light should turn green HTH Reza 04-17-2011 12:04 PM Hi to quote the last speaker in this thread. The yellow (amber) light it is for ps1 ie powersupply 1 who is busted or not operational. For IT professionals and network administrators, understanding these lights is crucial. Understanding LED indicators allows for rapid troubleshooting of switch issues.