3Com 3C16475BS User Manual - Page 17

Connecting a Network Device 17 Checking for Correct Operation After you power on the Switch, it automatically performs a power-on self-test (POST). During POST, the Power LED on the front panel of the Switch flashes green. When POST is complete, the Power LED turns green. If the Power LED turns yellow after POST, it means that POST failed and the Switch has entered fail-safe mode. Table 4 summarizes the possible colors for the Power LED after POST. Table 4 Possible Power LED Colors After POST Color State Green The unit is powered on and ready for use Yellow Power-on self-test or loopback test failed. The Switch is in fail-safe mode. This can happen if a ports or ports fail when the Switch is powered on. Off The unit is not receiving power: ■ Verify that the power cord is connected correctly, and then try powering on the Switch again ■ If the Switch still does not operate, contact your 3Com network supplier If POST fails, try the following: ■ Power off the Switch, and then power it on again. Check the Power LED and see if POST was successfully completed. ■ Reset the Switch. See "Resetting to Factory Defaults" on page 43. CAUTION: Resetting the Switch to its factory defaults erases all your settings. You will need to reconfigure the Switch after you reset it. If these do not resolve the issue: ■ Check the 3Com Knowledgebase for a solution. To visit the 3Com Knowledgebase Web site, start your Web browser, and then enter http://knowledgebase.3com.com. ■ Contact your 3Com network supplier for assistance. Connecting a Network Device To connect a network device to the Switch, use Category 5 unshielded or shielded (screened) 100 Ohm TP cables (or Category 3 cables for 10 Mbps connections). For optimal connections, ensure that the cable length for each connection is not longer than 100 m (328 ft).