3Com 3C16751A manual Straight-through Cable/Crossover Cable

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Port Status LED flashing. The port is partitioned, probably due to a network loop. Examine your connections and remove the loop. Each piece of equipment needs only one connection to your Hub.

Link between the Hub and another OfficeConnect hub not working. Check your connections; follow the information given in the “Connecting Another OfficeConnect Hub” section on page 11. It is likely that an Uplink/Normal switch is incorrectly set.

Port Status LED not lit for a port that has a connection. Check that you are using a ‘straight-through’ cable which is properly connected at both ends, and is not damaged. Refer to “Twisted Pair (TP) Cables” on page 8. Also check that the equipment connected to the Hub is powered on, operating correctly and contains the correct type of connection. Refer to Figure 6 to compare the wiring of a straight-through and a crossover cable.

Figure 6 Straight-through Cable/Crossover Cable

Normal

Pin

Pin

 

Uplink

Normal

Pin

Pin

 

Normal

port

 

port

port

 

port

Rx+

 

1

1

 

Rx-

Rx+

 

1

1

 

Rx+

 

2

2

 

 

2

2

 

Rx-

 

 

Rx+

Rx-

 

 

Rx-

 

3

3

 

 

3

3

 

Tx+

 

 

Tx-

Tx+

 

 

Tx+

 

4

4

 

 

4

4

 

 

 

 

 

 

 

 

 

 

 

5

5

 

 

 

 

5

5

 

 

 

 

 

 

 

 

 

 

Tx-

 

6

6

 

Tx+

Tx-

 

6

6

 

Tx-

 

 

 

 

 

7

7

 

 

7

7

 

 

 

 

 

 

 

 

 

 

 

8

8

 

 

 

 

8

8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

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Contents OfficeConnect Dual Speed Hub 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Introduction Creating your Network Page Small Network With OfficeConnect Hub IntroductionNetwork Utilization LEDs Creating Your NetworkDual Speed Hub 16-Front Port Status LEDsSixteen 10/100BASE-TX ports Power Adapter socketUplink/Normal switch Dual Speed Hub 16-RearHub Connections Before You StartWorkstation Connections Twisted Pair TP CablesStacking the Units Together Rubber FeetStacking Clip Securing Your Hub Positioning Your HubConnecting Workstations and Other Equipment to Your Hub Connecting Another OfficeConnect HubFast Ethernet 100Mbps Configuration Rules Ethernet 10Mbps Configuration Rules ExampleExample Making the Connection to Another Hub Checking Hub ConnectionsSpot Checks Problem Solving Straight-through Cable/Crossover Cable Networking Terminology Dimensions and Standards Dimensions and Operating ConditionsStandards Environmental Statement about the Documentation Environmental StatementsEnd Of Life Statement Regulated Materials StatementImportant Safety Information Wichtige Sicherheitshinweise Consignes Importantes DE Sécurité World Wide Web Site Online Technical Services3Com Knowledgebase Web Services Technical SupportSupport from 3Com Support from Your Network SupplierCountry Telephone Number Asia, Pacific Rim EuropeEurope, South Africa, and Middle East North America Country Telephone Number Latin AmericaCountry Telephone Number Fax Number Returning Products for Repair3Com Corporation Limited Warranty Warranties Exclusive Disclaimer Electromagnetic Compatibility Wall mounting screw hole guide 142mm 5.6in Part No. DUA 1675-1AAA02 Published June