Cisco 3750 POE Online and ready but POE not working

Hi,

We have a switch stack of 7 3750 switches. One switch just seemed to stop working, still has power. After restart, using the sh switch command, the switch seems to be stuck at initializing, after restart the of the stack, the switch shows ready. Its a POE switch and plugging a phone directly into the switch, no power. However plugging in a laptop works, data is working just not power no data. I used some basic commands, show config, ver, vlan, int and compared the configs to the other switches and everything looks good.  The switch in question has no error using sh int. Any suggestions greatly appreciated. Below is a output from sh int, for the switch in question,  all ports are shown the same.

FastEthernet5/0/20 is down, line protocol is down (notconnect)
  Hardware is Fast Ethernet, address is 0017.94b5.d016 (bia 0017.94b5.d016)
  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Auto-duplex, Auto-speed, media type is 10/100BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts (0 multicast)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 5 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out



Thanks,
jaya31Asked:
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aleghartCommented:
Is that switch empty?  Are you able to unplug just that single switch and let it reboot?

That may restore power, if the PSU is still in good shape.

Otherwise, the WS-C3750-48P does not have PSU that is a FRU (field-replaceable unit).  

A faulty PSU would require opening it up and installing replacement.  You might have luck getting a refurbished unit or a used unit from eBay.

You can try 'sh env all' or 'sh env power' and look for a faulty PSU.   But...if the switch is running, then the PSU is making power.  There is a separate section that is making power for the PoE ports.  That portion of the PSU could be faultly.
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jaya31Author Commented:
Also using the command sh logging i get that there was looping enabled on that port, please see below and a port on that switch was disabled, but if the port was disabled, would that cause the issue of POE not working. Also as of now we moved all users from that switch and its completely empty.

Fa5/0/36                     err-disabled 10           auto   auto 10/100BaseTX


000648: May 11 01:14:29: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/0/36, changed state to up
000649: May 11 01:15:24: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/0/36, changed state to down
000650: May 11 01:15:25: %LINK-3-UPDOWN: Interface FastEthernet5/0/36, changed state to down
000651: May 11 01:20:57: %LINK-3-UPDOWN: Interface FastEthernet5/0/36, changed state to up
000652: May 11 01:20:58: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/0/36, changed state to up
May 11 01:21:01: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on FastEthernet5/0/36. (FKKS3750PoE-48X6-5)
000653: May 11 01:21:02: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/0/36, changed state to down
May 11 01:21:01: %PM-4-ERR_DISABLE: loopback error detected on Fa5/0/36, putting Fa5/0/36 in err-disable state (FKKS3750PoE-48X6-5)000654: May 11 01:21:03: %LINK-3-UPDOWN: Interface FastEthernet5/0/36, changed state to down
FKKS3750PoE-48X6#sh int status
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aleghartCommented:
When the port is err-disabled, the PoE would also be shut down.

Can you 'show run interface Fa5/0/36' and paste here?  Redact any sensitive information.

Also, paste the config of an interface that is working.

I'm looking for 'power inline __' in the interface configuration.  In a "normal" PoE port, you should see no special config.

If the PoE is disabled, you'll see something like this:
interface FastEthernet2/0/5
 power inline never
end

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'show power inline' should show that the ports can run up to 15.4W or 15,400mW.  If your device draws more than this, then you'll need a newer switch that can handle more power per port.
Sw2-3750#sh power inline

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
2           370.0       15.4       354.6
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Fa2/0/1   auto   off        0.0     n/a                 n/a   15.4
Fa2/0/2   auto   on         15.4    Ieee PD             0     15.4
Fa2/0/3   auto   off        0.0     n/a                 n/a   15.4
Fa2/0/4   auto   off        0.0     n/a                 n/a   15.4
Fa2/0/5   off    off        0.0     n/a                 n/a   15.4
Fa2/0/6   auto   off        0.0     n/a                 n/a   15.4

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jaya31Author Commented:
Hi,

Please see configs for port 36 and a working port, didn't see power inline never, but will wait for your feedback. Also, if port 36 was disabled, would POE be disabled for the other ports, entire switch?. I ran the "sh power inline" however nothing reported as there is nothing plugged in right now.

show run interface Fa5/0/36
Building configuration...

Current configuration : 274 bytes
!
interface FastEthernet5/0/36
 switchport access vlan 10
 switchport voice vlan 20
 srr-queue bandwidth share 10 10 60 20
 srr-queue bandwidth shape  10  0  0  0
 mls qos trust device cisco-phone
 mls qos trust cos
 auto qos voip cisco-phone
 spanning-tree portfast
end

show run interface Fa4/0/17
Building configuration...

Current configuration : 274 bytes
!
interface FastEthernet4/0/17
 switchport access vlan 10
 switchport voice vlan 20
 srr-queue bandwidth share 10 10 60 20
 srr-queue bandwidth shape  10  0  0  0
 mls qos trust device cisco-phone
 mls qos trust cos
 auto qos voip cisco-phone
 spanning-tree portfast
end
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jaya31Author Commented:
Hi Also,

I ran the power inline command on the specific ports. Not sure if the off means it turned or nothing is plugged in.

show power inline  Fa5/0/36
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Fa5/0/36  auto   off        0.0     n/a                 n/a   15.4


show power inline  Fa4/0/17
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Fa4/0/17  auto   on         14.7    IP Phone 8865       4     15.4
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aleghartCommented:
NOTE:  If you paste your commands & output, use the 'CODE' button in the Experts-Exchange format bar.  It contains it in a box, and uses a monospaced typeface so console output is readable.

There are two columns for 'sh power inline'.  The 'Admin' column shows if it is in auto mode (normal/default for PoE switches).  In my example, port Fa2/0/5 had power disabled, so its status under 'Admin' is 'off'.  Other ports are 'auto'...so they should power up when an acceptable device is plugged in.

Run the command 'show power inline'.  Not just for one specific interface.  The first few lines of output will show each switch, the power supply, used, and available power.  This is important, in case somebody swapped a 350W PSU in...which is enough to run the switch for data, but not enough to run PoE.   Stack-power on 3750x and 3850x will form a power bus and share power.  But, normally, PoE switches can only supply as much power as is available from the internal PSU(s).

Sample of a stack of 3850x PoE:
3850-01#sh power inline

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
1          1440.0      180.0      1260.0
2          1440.0      111.7      1328.3
3          1440.0      153.7      1286.3
4          1440.0      106.0      1334.0
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/1   auto   off        0.0     n/a                 n/a   30.0
Gi1/0/2   auto   on         6.0     IP Phone 6941       2     30.0
Gi1/0/3   auto   on         6.0     IP Phone 6941       2     30.0
Gi1/0/4   auto   on         6.0     IP Phone 6941       2     30.0
Gi1/0/5   auto   on         6.0     IP Phone 6941       2     30.0

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I
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jaya31Author Commented:
Hi,

Thanks for code tip. See below the sh power inline output. Switch 5 is set to auto, same as the rest.

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
1           370.0       40.3       329.7
2           370.0      163.4       206.6
3           370.0      187.7       182.3
4           370.0      297.1        72.9
5             n/a        n/a         n/a
7           370.0       56.8       313.2
8           370.0       31.5       338.5

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Fa4/0/27  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/28  auto   on         14.7    IP Phone 8865       4     15.4
Fa4/0/29  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/30  auto   on         14.7    IP Phone 8865       4     15.4
Fa4/0/31  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/32  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/33  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/34  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/35  auto   on         14.7    IP Phone 8865       4     15.4
Fa4/0/36  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/37  auto   on         6.3     IP Phone 7961       2     15.4
Fa4/0/38  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/39  auto   on         6.4     IP Phone 8845       2     15.4
Fa4/0/40  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/41  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/42  auto   on         14.7    IP Phone 8865       4     15.4
Fa4/0/43  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/44  auto   on         14.7    IP Phone 8865       4     15.4
Fa4/0/45  auto   on         14.7    IP Phone 8865       4     15.4
Fa4/0/46  auto   off        0.0     n/a                 n/a   15.4
Fa4/0/47  auto   on         6.3     IP Phone 7961       2     15.4
Fa4/0/48  auto   on         14.7    IP Phone 8865       4     15.4
Fa5/0/1   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/2   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/3   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/4   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/5   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/6   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/7   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/8   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/9   auto   off        0.0     n/a                 n/a   15.4
Fa5/0/10  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/11  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/12  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/13  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/14  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/15  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/16  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/17  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/18  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/19  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/20  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/21  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/22  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/23  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/24  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/25  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/26  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/27  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/28  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/29  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/30  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/31  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/32  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/33  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/34  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/35  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/36  auto   off        0.0     n/a                 n/a   15.4
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Fa5/0/37  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/38  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/39  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/40  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/41  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/42  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/43  auto   off        0.0     n/a                 n/a   12.0
Fa5/0/44  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/45  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/46  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/47  auto   off        0.0     n/a                 n/a   15.4
Fa5/0/48  auto   off        0.0     n/a                 n/a   15.4
Gi7/0/1   auto   off        0.0     n/a                 n/a   15.4
Gi7/0/2   auto   off        0.0     n/a                 n/a   15.4
Gi7/0/3   auto   off        0.0     n/a                 n/a   15.4
Gi7/0/4   auto   off        0.0     n/a                 n/a   15.4
Gi7/0/5   auto   off        0.0     n/a                 n/a   15.4
Gi7/0/6   auto   off        0.0     n/a                 n/a   15.4
Gi7/0/7   auto   off        0.0     n/a                 n/a

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aleghartCommented:
Your switch does not have PoE.  See your own output:
Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
1           370.0       40.3       329.7
2           370.0      163.4       206.6
3           370.0      187.7       182.3
4           370.0      297.1        72.9
5             n/a        n/a         n/a
....

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Module 5 should be Switch5.  There is no inline power available from that switch.

Can you do a 'show version' to confirm the model of the switch ?

Here is an example of a switch stack that does not have PoE on all stack members.  The first command demonstrates the one or more switches does not offer PoE.  The second command gives the model number of all switch stack members.  You'll have to scroll through the output and just copy the relevant lines

show power inline
Sw3850-01#sh power inline

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
1             n/a        n/a         n/a
2             n/a        n/a         n/a
3           720.0        0.0       720.0
....

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show version
Sw3850-01#sh ver

....
Switch Ports Model              SW Version        SW Image              Mode
------ ----- -----              ----------        ----------            ----
*    1 20    WS-C3850-12S       03.06.06.E        cat3k_caa-universalk9 BUNDLE
     2 20    WS-C3850-12S       03.06.06.E        cat3k_caa-universalk9 BUNDLE
     3 32    WS-C3850-24P       03.06.06.E        cat3k_caa-universalk9 BUNDLE
....

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jaya31Author Commented:
Hi,

Sh ver output below. Also checked the front of the switch and its labled PoE.  Also, please see the link below from Cisco, I think we did everything with exception of shut, no shut, not sure the command to run for a specific port to test.






Switch   Ports  Model              SW Version              SW Image
------   -----  -----              ----------              ----------
     1   52     WS-C3750-48P       12.2(25)SEB4            C3750-IPBASE-M
     2   52     WS-C3750-48P       12.2(25)SEB4            C3750-IPBASE-M
     3   52     WS-C3750-48P       12.2(25)SEB4            C3750-IPBASE-M
*    4   52     WS-C3750-48P       12.2(25)SEB4            C3750-IPBASE-M
     5   52     WS-C3750-48P       12.2(25)SEB4            C3750-IPBASE-M
     7   52     WS-C3750G-48PS     12.2(25)SEB4            C3750-IPBASE-M
     8   52     WS-C3750-48P       12.2(25)SEB4            C3750-IPBASE-M

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jaya31Author Commented:
Sorry this is the link from cisco the section on - No PoE On All Ports or a Group of Ports step 6

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/troubleshooting/g_power_over_ethernet.html
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jaya31Author Commented:
Hi,

Restarted the switch a couple of times and the same. I also ran this command "sh post" and on SW 5 it brought the result below, indicates as you said the PSU controlling the POE is faulty.

POST: Inline Power Controller Tests : Begin
POST: Inline Power Controller Tests : End, Status Failed

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jaya31Author Commented:
Thank you very much for you help and guidance with isolating the issue.
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