Basic Troubleshooting Tips - HP J4093A Installation Manual

Troubleshooting

Basic Troubleshooting Tips

Basic Troubleshooting Tips
Most problems are caused by the following situations. Check for these items
first when starting your troubleshooting:
3-2
Incorrect switch-to-switch or switch-to-hub connections. If you
have connected your switch to another switch or a hub by using twisted-
pair cable from an RJ-45 MDI-X connector on your switch to an MDI-X
connector on the other switch or hub, you must use a crossover cable.
If you have used a straight-through cable, the connection will not work.
The LED for the port you are using will not come on when you connect
the cable.
Most switch and hub ports are wired as MDI-X ports, so for these switch-
to-switch or switch-to-hub connections use a crossover cable. LAN
adapters in end nodes are normally wired as MDI ports, as are some ports
on hubs and switches. For connections from the switch to these MDI
ports, use a straight-through cable. See appendix B, "Cables and
Connectors" for pinouts and correct cable wiring for crossover and
straight-through twisted-pair cables.
Faulty or loose cables. Look for loose or obviously faulty connections.
If they appear to be OK, make sure the connections are snug. If that does
not correct the problem, try a different cable.
Non-standard cables. Non-standard and miswired cables may cause
numerous network collisions and other network problems, and can seri-
ously impair network performance. Use a new correctly-wired cable or
compare your cable to the cable in appendix B, "Cables and Connectors"
for pinouts and correct cable wiring. A category 5 cable tester is a
recommended tool for every 100Base-T network installation.
Improper Network Topologies. It is important to make sure you have
a valid network topology. Common topology faults include excessive
cable length and excessive repeater delays between end nodes. If you have
network problems after recent changes to the network, change back to
the previous topology. If you no longer experience the problems, the new
topology is probably at fault. Refer to the Network Design Guide for
topology configuration guidelines. This guide can be found online at the
HP World Wide Web site for networking products, http://www.hp.com/go/
[Tech Library]
procurve under the button.