3Com 3C16750 User Manual

Contents

7PROBLEM SOLVINGThe Hub has been designed to aid you whendetecting and solving possible problems with yournetwork. These problems are rarely serious; thecause is usually a disconnected or damaged cable, orincorrect configuration. If this section does not solveyour problem, contact your supplier for informationon what to do next.Perform these actions first:Q Ensure all network equipment is powered on.Q Power each piece of network equipment off, waitabout 5 seconds and then power each one on.Check the following symptoms and solutions:Power LED not lit. Check your power adapterconnection. If there is still no power, you may have afaulty power adapter which needs replacing with anidentical OfficeConnect power adapter. Do not useany other power adapter with the Hub.Port Status LED not lit for a port that has aconnection. Check that you are using a‘straight-through’ cable which is properly connectedat both ends, and is not damaged. Refer to “TwistedPair (TP) Cables” on page 3. Also check that theequipment connected to the Hub is powered on,operating correctly and contains the correct type ofconnection.10Mbps Port Status LED lit for a port with a100Mbps device connected. This may be becausethe cable is not of a high enough quality to carry FastEthernet signals (we recommend you use aCategory 5 cable), or due to a problem with thenetwork card (NIC) of the attached equipment.Port Status LED flashing. The port is partitioned,probably due to a network loop. Examine yourconnections and remove the loop. Each piece ofequipment needs only one connection to your Hub.Link between the Hub and anotherOfficeConnect hub not working. Check yourconnections; follow the information given in the“Connecting Another OfficeConnect Hub” sectionon page 5. It is likely that an MDI/MDIX switch isincorrectly set.Alert LED continuously lit. There is a problem withthe network. Check the Port Status LEDs to try toidentify the port that is causing the problem. If oneof the Port Status LEDs is flashing, that port haspartitioned, probably due to a network loop.Examine your connections and remove the loop.Each piece of equipment needs only one connectionto your Hub.If you cannot identify such a port, remove the portconnections one at a time, waiting a few secondsbetween each port. If the Alert LED goes off, there iseither a network loop (see above), or an excessiveamount of traffic on that port connection. Check theNetwork Utilization LEDs to see if the network isheavily loaded (over 80%). Some pieces of networkequipment operate by sending out frames regularly.Refer to the documentation that accompanies thepiece of network equipment.If the Alert LED is still lit after removing all of yourconnections, there may be a problem with your Hub.Power it off, wait about 5 seconds and then powerit on. If the Alert LED comes back on continuously,contact your supplier.Dimensions and Operating ConditionsOfficeConnect Dual Speed Hub 8StandardsFunctional: ISO 8802/3IEEE 802.3, 802.3uSafety: UL 1950, EN 60950CSA 22.2 #950, IEC 950Emissions: EN 55022 Class B*FCC Part 15 Class B*ICES-003 Class B*VCCI Class B*AS/NZS 3548 Class B*EN50082-1* Screened (shielded) cables must be used to ensurecompliance with these EMC standards. Refer to “EMCStatements” on page 8 for conditions of operation.Environmental: EN 60068 (IEC 68)Acoustic Noise: ISO 7779ISO 9295DIMENSIONS AND STANDARDS

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