18 CHAPTER 1: INTRODUCING THE S WITCH 4500 FAMILYUnit LED The Unit LED is a seven segment display visible on the front of the Switch.The Unit LED can be used to indicate the unit number in a fabric, POSTtest ID and software upgrade information. In the unlikely event of ahardware fault occurring, the Unit LED may be used to help diagnose theproblem. For information on using the Unit LED for problem solving, see“Solving Problems Indicated by LEDs” on page 68LEDs Table 5 lists LEDs visible on the front of the Switch, and how to read theirstatus. For information on using the LEDs for problem solving, see“Solving Problems Indicated by LEDs” on page 68.Table 5 LED BehaviorLED Color IndicatesUnit LEDGreen Power On Self Test (POST) is in progress. During POST a thetest ID number appears in the Unit LED (seven segmentdisplay).orSoftware download is in progress. During softwaredownload, a clockwise cycling bar appears in the Unit LED.Green flashing The Switch has failed POST. The Unit LED flashes thenumber of the test that has failed.Green flashing ‘f’ There has been a fan failure.Green flashing ‘t’ The Switch is over temperature and unit temperature iscritical.PWR LEDGreen The Switch is powered-up and operating normally.Green flashing Self Test (POST) or Software Download is in progress.Yellow flashing One or more ports have failed POST.Red The Switch has failed its Power On Self Test.Off The Switch is not receiving power or there is a fault with thePower Supply Unit.Mode LED (3CR17571-91 and 3CR17572-91 only)Speed Green 10/100 Port Speed and Activity, 1000 SFP Status andActivity, or Stack Status and Activity.Duplex Yellow 10/100 Duplex and Activity, 1000 SFP Duplex and Activity,or Stack ActivityPoE Red 10/100 Port showing PoE Information
