3com 4400 SE User Manual

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.

If power is not being supplied to a device connected to a 
Switch 4400 PWR, you should do the following checks:

■

Check that the device is compliant with the 802.3af standard ref. [18]. 

The 4400 PWR will only supply power through the front panel ports to 
802.3af compliant devices.

■

Check that the power budget for the Switch has not been exceeded.

If the power budget has been exceeded, then by default, the powered 
device connected to the Power over Ethernet port with the lowest 
priority port will lose power. However, if all the devices connected to 
the Switch have equal priority levels, then the port with the highest 
number will lose power.

By default the Switch will allow a device to receive power as long as 
the Power over Ethernet power supply has 18 watts spare in its power 
budget. If this much power is not available the device will not be 
powered (unless it has a higher priority than existing powered ports) 
and a Power over Ethernet fault will be reported for that port. If 
enough power subsequently becomes available the port will be 
powered.

■

Check that the port has not had a power limit imposed upon it. 

DUA1720-3AAA07.book  Page 61  Wednesday, March 17, 2004  1:14 PM