HP ProCurve 10, Installation Manual

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Troubleshooting
Basic Troubleshooting Tips
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• 100Base-T topology rules: Be aware that the topology rules for
100Base-T networks are much more restrictive than for 10Base-T.
You may have to redo an existing 10Base-T topology for 100Base-T
products.
The HP 10/100 hubs operate as Class II hubs when being used for
100Base-T networking. Some basic Class II 100Base-T Hub rules are
as follows:
–
The maximum segment length for a hub-to-end node connection
is 100 meters.
– At most one hub can be cascaded from any of the hub ports that
are operating at 100 Mbps.
– Do not mix Class I and Class II hubs when cascading.
– When cascading two hubs together, the maximum distance sepa-
rating them is 5 meters.
– You must use 100-ohm Category 5 UTP cable in the 100Base-T
installations.
See the card “Connectivity Rules for 100T Networks” included with
your hub for illustrations of these rules.
■
Full-duplex link to the hub. Regular hub ports, including the ports on
the HP 10/100 hubs, only operate in half-duplex mode. If the attached
device is running in full-duplex mode, it will cause a high number of late
collisions on the network, degrading performance for all nodes. The HP
10/100 hubs must not be connected to devices that are configured for full-
duplex operation.
■
Non-compatible Speed Configuration. For the Hub 12M and Hub 24M,
make sure that you have not configured any port to operate at a speed
that is not compatible with the attached device (10 Mbps or 100 Mbps).
■
Faulty or loose network cables. Look for loose or obviously faulty
connections. If they appear to be OK, try a different cable.
9934.book Page 3 Thursday, January 14, 1999 12:39 PM