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I'm probing an issue where 4 PoE cameras can't get powered on. Switch model Dell N2048P Series. The "P" at the end of the model stands for "PoE Enabled" so, this feature is/should be available.

The default behavior of this switch is always try to probe PoE devices unless power inline never is set at port configuration scope. However show power inline on any port show the Test-Fail status, no voltage and empty temperature.

SWDEP_08_XX#show power inline gigabitethernet 1/0/41

Port      Powered Device           State Priority Status     Class   Power[mW]
--------- ------------------------ ----- -------- ---------- ------- ---------
Gi1/0/41                           auto  Low      Test-Fail  Unknown


Overload Counter............................... 0
Short Counter ................................. 0
Denied Counter................................. 0
Absent Counter................................. 0
Invalid Signature Counter...................... 0
Output Volts................................... 0
Output Current................................. 0
Temperature.................................... N/A

What I have done so far after some Dell Forums browsing and manual pages reading:

  • Updated firmware and cpld. My switch was using a version lower than the one reported on this thread.
  • Tested the cameras on other same model switch and they got up and running.
  • Tried all possible power inline detection schemes inside global config scope.
  • Tried enabling and disabling power features or reseting them on individual ports as explained here
  • Tried other switch ports(and all of them show Test-fail)
  • Switch got physically disconnected from energy

Equipments that don't rely on PoE are working as expected(gigabit auto).

Comparing results of the switch with the healty one:

Non-working Switch:

SWDEP_08_XX#show power inline

Unit Status
===========

Unit........................................... 1
Power.......................................... On
Total Power.................................... 0 Watts
Threshold Power................................ 0 Watts
Consumed Power................................. 0 Watts
Usage Threshold................................ 90%
Power Management Mode.......................... Dynamic
Power Detection Mode........................... dot3at+legacy

SWDEP_08_XX#show system temperature

System Thermal Conditions:

Unit Temperature State
      (Celsius)
---- ----------- -----------
1    49          Good

Temperature Sensors:

Unit Description        Temperature
                         (Celsius)
---- ------------------ -----------
1    MAC                49
1    PHY                37
1    POE Ctrl 1         0
1    POE Ctrl 2         0
1    POE Ctrl 3         0
1    POE Ctrl 4         0
1    POE Ctrl 5         0
1    POE Ctrl 6         0

Working Switch:

SWDEP_05_XX#show power inline

Unit Status
===========

Unit........................................... 1
Power.......................................... On
Total Power.................................... 850 Watts
Threshold Power................................ 765 Watts
Consumed Power................................. 7 Watts
Usage Threshold................................ 90%
Power Management Mode.......................... Dynamic
Power Detection Mode........................... dot3at+legacy

SWDEP_05_XX#show power inline gigabitethernet 1/0/41

Port      Powered Device           State Priority Status     Class   Power[mW]
--------- ------------------------ ----- -------- ---------- ------- ---------
Gi1/0/41                           auto  Low      On         Class0  3200

Overload Counter............................... 0
Short Counter ................................. 0
Denied Counter................................. 0
Absent Counter................................. 0
Invalid Signature Counter...................... 0
Output Volts................................... 53
Output Current................................. 60
Temperature.................................... 39


SWDEP_05_XX#show system temperature

System Thermal Conditions:

Unit Temperature State
      (Celsius)
---- ----------- -----------
1    52          Good

Temperature Sensors:

Unit Description        Temperature
                         (Celsius)
---- ------------------ -----------
1    MAC                52
1    PHY                39
1    POE Ctrl 1         41
1    POE Ctrl 2         41
1    POE Ctrl 3         41
1    POE Ctrl 4         39
1    POE Ctrl 5         43
1    POE Ctrl 6         49

My question: Is the Test-fail status and the empty temperature on the POE control modules of the switch enough to prove this specific PoE hardware inside the switch is faulty?

  • 1
    Apparently, that switch has no power for PoE: Total Power.................................... 0 Watts. – Ron Maupin Nov 28 '18 at 19:00
  • Hi @RonMaupin. Yeah, one of the suspects i had is that it could also be firmware related (dell.com/community/Networking-General/…) – user52167 Nov 28 '18 at 19:15
  • 1
    Looks like the switch doesn't support PoE - the PoE PSU might have died or has been removed. – Zac67 Nov 28 '18 at 19:26
  • PoE support should be available since it is a switch that ends with the "P" on its number series( N2040P ). Dell uses this P on it's N Series to show what switches are PoE enabled. I'll add this detail at the question. – user52167 Nov 28 '18 at 19:27
  • 3
    @nwildner The "Total Power" figure should show what the PSU can deliver, regardless of what's currently used. The "0 W" pretty clearly shows there's something wrong. – Zac67 Nov 28 '18 at 19:34
3

(converted from comments)

The "Total Power" figure should show what the PSU can deliver, regardless of what's currently in use. The "0 W" pretty clearly shows there's something wrong.

Possibly, the internal PoE PSU has died or is disconnected/removed. Also, there may be an external PoE PSU connected that isn't powered or has died.

  • 2
    Or something needs to be physically reset -- not "reload", but actually disconnected from power. – Ricky Beam Nov 29 '18 at 0:44
  • Agree with Ricky. I have seen this with a few vendors. Even Cisco has switches that are affected by PoE related issues that aren't resolved unless you do a full power disconnect (i.e. a reload doesn't restore proper service), especially when stacked. – YLearn Nov 29 '18 at 1:21
  • @RickyBeam Good point - the likely PSU issue might be temporary. – Zac67 Nov 29 '18 at 6:30
  • @RickyBeam I would replace PoE modules on this switch but they are INTERNAL(built-in). Only stack modules are replaceable. This Switch got Full powered off(disconnected from energy) twice the day i was probing it. – user52167 Nov 29 '18 at 9:53

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