Trunk Interface detecting PoE

[gabsnet]

Has anyone seen that cisco behaviour ?

I've got two devices connected to each other via Ethernet port, trunked.
Core: WS-C3750X-48P  15.2(4)E10 connecting to Secondary: WS-C3750X-48P 15.2(4)E10.

And I've got alerts on the Core SW that is detected PoE.

%ILPOWER-5-IEEE_DISCONNECT: Interface gi1/0/47: PD removed
%ILPOWER-7-DETECT: Interface gi1/0/47: Power Device detected: IEEE PD

Can you guys think any reason why that would happen? 

I simply disable the power inline on my trunk interface, as it was causing disconnections and I think might have affected the STP too.

[Mark Elsen]

  - @gabsnet              Post the running configuration of  gi1/0/47
                                  Use the command show cdp neighbors detail on both switches and look
                                                at the reported info's for the trunk ports 

  M.

[gabsnet]

Hello Mark.

See the configs:
---CORE SW
interface GigabitEthernet1/0/47
description DOWNLINK-MAZDA-PARTS
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport mode trunk
power inline never

FSA-SPT-MZ-SW-01#sh cdp neighbors g1/0/47 detail
-------------------------
Device ID: FSA-SPT-MZ-SW-02
Entry address(es):
IP address: X.X.X.X
Platform: cisco WS-C3750X-48P, Capabilities: Switch IGMP
Interface: GigabitEthernet1/0/47, Port ID (outgoing port): GigabitEthernet1/0/48
Holdtime : 142 sec

Version :
Cisco IOS Software, C3750E Software (C3750E-UNIVERSALK9-M), Version 15.2(4)E10, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2020 by Cisco Systems, Inc.
Compiled Tue 31-Mar-20 13:22 by prod_rel_team

advertisement version: 2
VTP Management Domain: 'JFAG'
Native VLAN: 100
Duplex: full
Management address(es):
IP address: X.X.X.X

Total cdp entries displayed : 1

---SECONDARY SW
description UPLINK-MZ-SW01
switchport trunk encapsulation dot1q
switchport trunk native vlan 100
switchport mode trunk
spanning-tree port-priority 16
end

FSA-SPT-MZ-SW-02#sh cdp neighbors g1/0/48 detail
-------------------------
Device ID: FSA-SPT-MZ-SW-01
Entry address(es):
IP address: X.X.X.X
Platform: cisco WS-C3750X-48P, Capabilities: Switch IGMP
Interface: GigabitEthernet1/0/48, Port ID (outgoing port): GigabitEthernet1/0/47
Holdtime : 139 sec

Version :
Cisco IOS Software, C3750E Software (C3750E-UNIVERSALK9-M), Version 15.2(4)E10, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2020 by Cisco Systems, Inc.
Compiled Tue 31-Mar-20 13:22 by prod_rel_team

advertisement version: 2
VTP Management Domain: 'JFAG'
Native VLAN: 100
Duplex: full
Management address(es):
IP address: X.X.X.X

Total cdp entries displayed : 1

[Mark Elsen]

  -  @gabsnet          Remove the power inline never directive from Gi1/0/47

  M.

[pieterh]

>>> Can you guys think any reason why that would happen? <<< 
no not really, a 3750 should not present itself as a PD, only as PSE
there are some switches that can be powered over PoE and so be a PD but the 3750 is not one of those

maybe an external PoE(+)  injector is accidentally connected in the path?