HP ProCurve 5400zl Installation And Getting Started Manual page 70

Troubleshooting
Basic Troubleshooting Tips
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5-2
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 recom-
mended 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.
In addition, you should make sure that 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.
With your Series 5400zl Switches, if you wish to build redundant paths
between important nodes in your network to provide some fault toler-
ance, 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, the web browser interface, or ProCurve Manager.
The Series 5400zl Switches also support Trunking, which allows multiple
network cables to be used for a single network connection without
causing a data path loop. See the Management and Configuration Guide
for more information on Spanning Tree and on Trunking, which is on the
ProCurve Web site. See
Connecting to devices that have a fixed full-duplex configuration.
The RJ-45 ports on the Series 5400zl Switches are all configured as "Auto".
That is, when connecting to attached devices, the switch will operate in
one of two ways to determine the link speed and the communication mode
(half duplex or full duplex):
• if the connected device is also configured to Auto, the switch will
automatically negotiate both link speed and communication mode
• if the connected device has a fixed configuration, for example 100
Mbps, at half or full duplex, the switch will automatically sense the
link speed, but will default to a communication of half duplex
page 5-1 for details.