HP J4819A, Installation And Getting Started Manual

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4-2
Troubleshooting
Basic Troubleshooting Tips
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■ 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 Switch 5300xl Series, 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 Switch 5300xl Series 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
that is on the ProCurve Web site,
www.procurve.com
for more information
on Spanning Tree and on Trunking.
■ Connecting to devices that have a fixed full-duplex configuration.
The RJ-45 ports on the Switch 5300xl Series 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
Because the Switch 5300xl Series 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 that all devices connected to the Switch 5300xl Series are config-
ured to auto negotiate, or are configured to connect at half duplex (all
hubs are configured this way, for example).