HP ProCurve 408 Installation Manual page 30

Troubleshooting
Basic Troubleshooting Tips
MDI), use straight-through cable. See appendix B, "Cables and
Connectors" for pinouts and correct cable wiring for crossover
and straight-through twisted-pair cables.
Connecting to devices with a fixed full-duplex configura-
tion. The Switch 408 ports are set to auto-negotiate the link
characteristics. 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 set to auto negotiate, the
switch will automatically negotiate both link speed and
communication mode
• if the connected device has a fixed configuration, for example
(100 Mbps, and half or full duplex), the switch will automat-
ically sense the link speed, but will default to a communica-
tion mode of half duplex
Because the Switch 408 behaves in this way (in compliance with
the IEEE 802.3u standard), if a device connected to the switch
has a fixed configuration at full duplex, the device will not
connect correctly to the Switch 408. The result will be high error
rates and high collision rates, and very inefficient communica-
tions between the switch and the device.
Make sure that all devices connected to the Switch 408 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 they appear to be OK, make sure the connections
are secure. 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 seriously impair network performance. Use a new
correctly-wired cable or compare your cable to the cable in
3-2