Unit Overview — Front 1-1110BASE-T PortsThe Switch has 12 or 24 10BASE-T RJ45 ports con-figured as MDIX (cross-over), which provide a full10Mbps bandwidth to attached endstations. Themaximum segment length is 100m (328ft) over cat-egory 3, 4, or 5 UTP cable.As these ports are configured as MDIX (cross-over),you need to use a cross-over cable to connect todevices whose ports are MDIX-only. Most of the10BASE-T ports in 3Com devices are MDIX-only.100BASE-TX PortThe Switch has a single Fast Ethernet 100BASE-TXRJ45 port configured as MDIX (cross-over), whichprovides a 100Mbps connection to, for example, alocal server. The maximum segment length is 100m(328ft) over category 5 UTP or STP cable.As this port is configured as MDIX (cross-over), youneed to use a cross-over cable to connect to deviceswhose ports are MDIX-only. Most of the100BASE-TX ports in 3Com devices are MDIX-only.LEDsThe table below describes the LED behavior on theSwitch. For more details about corrective action inthe event of a problem, refer to “LEDs” on pageC-1.LED Color IndicatesTCVR Yellow Port 1 is a Transceiver Module fitted to therear of the unit.Port Status LEDsPacket Yellow Frames are being transmitted/received on theport.Status Green Link is present; port is enabled.Green flashing Link is present; port is disabled.Off Link is not present.Plug-in Module Status LEDsPacket Yellow Frames are being transmitted/received on thePlug-in Module port.Status Green Link is present; port is enabled.Green flashing Link is present; port is disabled.Green flashing(long on, shortoff)Refer to the “SuperStack II Switch ATMOC-3c Module User Guide”.Yellow Plug-in Module has failed its Power On SelfTest (if the MGMT LED is flashing yellow), orthe agent software of the Plug-in Module isnot installed correctly.Yellow flashing Plug-in Module is not recognized.Off Link is not present or Plug-in Module is notinstalled in the Switch.Unit Status LEDsPower Green Switch is powered-up.MGMT Green Switch is operating normally.Green flashing Switch or Plug-in Module is either down-loading software or initializing (whichincludes a Power On Self Test).Yellow Switch has failed its Power On Self Test.Yellow flashing Plug-in Module has failed its Power On SelfTest.
