Solving Hardware Problems
49
The Unit LED is flashing green
The Switch unit physically forms a stack with other Switch 4400 units, but 
cannot be managed as part of that stack because one or more units have 
not been upgraded to software version 2.0 or later. You must upgrade 
each unit in the stack to this software version, which is available on the 
CD-ROM that accompanies your Switch.
Solving Hardware 
Problems
In the rare event of your Switch unit experiencing a hardware failure, 
refer to the list of suggested solutions below.
An expansion module is installed and the unit will not power up
Ensure that the expansion module is fully seated in the slot and the 
connectors are engaged so that the securing screws can be tightened.
An SNMP fan fail trap is received
1 Power off the unit.
2 Check that the air vents are not obstructed.
3 Power cycle the unit. To do this, remove and reconnect the AC mains 
supply. If the unit has no AC main supply, remove and reconnect the DC 
RPS supply.
4 If a further fan fail trap is received, return the unit.
Unit fails, no SNMP fan fail trap is received
1 Power cycle the unit. To do this, remove and reconnect the AC mains 
supply. If the unit has no AC mains supply, remove and reconnect the DC 
RPS supply.
2 Check the command line interface (system summary command) to 
determine whether a thermal shutdown has occurred.
3 If no, return the unit:
If yes, check that:
■
The air vents are not obstructed.
■
The ambient temperatures and environmental conditions meet those 
specified in Appendix C
.
4 Power cycle the unit. If a further thermal shutdown occurs, and all 
environmental conditions are satisfactory, return the unit to 3Com.
DUA1720-3AAA03_online.book  Page 49  Monday, March 25, 2002  10:48 AM