3Com XLPCI Troubleshooting Network Connection Problems, Eliminating Potential Causes of Problems

TROUBLESHOOTING

C NETWORK CONNECTION

PROBLEMS

This appendix provides information about using a crossover cable to troubleshoot network problems when you know that the 3C900B NIC is working, but you cannot send or receive network traffic.

When you work with 10BASE-T cabling, concentrators, and NICs from different vendors, it is possible to connect everything but still have no communication between file servers and workstations. When there are several unknown variables, it is difficult to determine which component is failing.

Eliminating Potential Causes of Problems

Follow these steps to narrow the range of possible causes of some common problems:

1Determine whether your equipment complies with the 10BASE-T standard.

This is particularly important for data concentrators (hubs or repeaters).

2Connect a straight-through cable from the PC to the hub.

The hub performs an internal crossover so that the signal can go from TD+ to RD+ and TD– to RD–. When you look at an RJ-45 connector from the front (that is, the opposite side from where the wires enter the connector), pin 1 is identified on the right-hand side when the metal contacts are facing up.

3Make sure that the TD+ and TD– wires are twisted together, and that the RD+ and RD– wires are twisted together.

Using wires from opposing pairs can cause signals to be lost.