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4-2

Troubleshooting

Basic Troubleshooting Tips

Caution Because the E2620 Switches behave in this way (in compliance with the

IEEE 802.3 standard), if a device connected to the switch has a fixed

configuration at full duplex, the device will not connect correctly to the

switch. The result will be high error rates and very inefficient communi-

cations between the switch and the device.

Ensure all devices connected to the E2620 Switches are configured to auto

negotiate, or are configured to connect at half duplex (all hubs are

configured this way, for example).

■ Faulty or loose cables. Look for loose or obviously faulty connections.

If the cables 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

network collisions and other network problems, and can seriously impair

network performance. Use a new correctly-wired cable or compare your

cable to the cable in appendix B, “Switch Ports and Network Cables” for

pinouts and correct cable wiring. A category 5 cable tester is a

recommended tool for every 100Base-TX and 1000Base-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. Sample topologies are shown at the end of

chapter 2 in this book, and some topology configuration guidelines can

be found online at the HP Web site,

www.hp.com/networking/support.

In addition, you should make sure your network topology contains no

data path loops. Between any two end nodes, there should be only one

active cabling path at any time. Data path loops will cause broadcast

storms that will severely impact your network performance.

For your Switch, if you wish to build redundant paths between important

nodes in your network to provide some fault tolerance, you should enable

Spanning Tree Protocol support on the switch. This ensures that only

one of the redundant paths is active at any time, thus avoiding data path

loops. Spanning Tree can be enabled through the switch console or the

web browser interface.

Questions and Answers:

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HP E2620 Specifications

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