3Com Switch 4500 Family, Getting Started Manual, Page: 71 / 134

Solving Hardware Problems 71
Auto-negotiation problems will occur with 10BASE-T or 100BASE-T
where auto-negotiation is disabled and incorrect cables are being used
(cross-over or straight)
Auto-negotiation problems will occur with fiber if:
■
The Receiver (RX) and Transceiver (TX) cable connectors are
swapped
■
Fibers are broken
■
Auto-negotiation differs at either end (a link appears at the ‘fixed’
end and not at the auto-negotiation end)
Solving Hardware
Problems
In the rare event of your Switch unit experiencing a hardware failure,
refer to the list of suggested solutions below.
A fan failure warning message is received
Your Switch has a fan monitoring system that will generate fan failure
warning messages. Fan failure could potentially reduce the lifetime of the
Switch. The monitoring system polls the fan status at periodic intervals
while the unit is powered up.
If one fan has failed in the Switch, a warning message will be generated
in the following ways:
■
Unit LED — the seven segment display will show a green flashing ‘f’.
■
RMON Trap — if configured, an RMON trap is generated and sent to
the management workstation.
■
Command Line Interface — an indication of a general hardware
failure is provided through the Top level menu displayed when logging
on to the CLI. For more detailed information about the failure select
the
display logbuffer
command.
■
Web interface — an indication of fan failure is provided through the
Device Summary table for the specific unit. In addition all Summary
tables turn red to indicate the fan failure.
If a fan failure warning message is generated:
1 Power off the unit.
2 Check that the air vents are not obstructed.