I ́m powering the 3com switch with the poe of the extreme port.
this the result of the command:
Port State Class Volts Curr Power Fault
3:18 delivering class4 56.0 78 4.300 None
I think that the extreme port is not giving the power that 3com needs in order to deliver enough power to feed a poe device.
This could help if the 3Com supports LLDP
This is the output for that port.
Configured Admin State: enabled
Inline Power State : delivering
MIB Detect Status : delivering
Operator Limit : 30000 milliwatts
PD Class : class4
Max Allowed Power : 30.0 W
Measured Power : 4.200 W
Line Voltage : 56.0 Volts
Current : 76 mA
Fault Status : None
Detailed Status : Delivering power to IEEE PD
Priority : high
Detection : 802.3af-only
If power is supplied to the uplink port by 802.3at or by the external power supply, then ports 1 and 2 may act as PoE PSE (Power Source Equipment) and may also provide power to other devices plugged into those ports.
If power is supplied by 802.3af, then port 1 and 2 will not be able to supply PoE power.
Based on the outputs they were negotiated using 802.3af.
How to contact Extreme Networks Global Technical Assistance Center (GTAC)