loopback on port

[tetzPeha]

Hi,

on a 5700 switch, i have this every time :

dis loopback-detection
Loopback detection is enabled.
Loopback detection interval is 30 second(s).
Loopback is detected on following interfaces:
  Interface                  Action mode
  Ten-GigabitEthernet2/0/33  none



%Dec 21 23:08:53:317 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/5/LPDT_RECOVERED: -Slot=2; Loopback on Ten-GigabitEthernet2/0/33 recovered.
%Dec 21 23:07:23:218 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/4/LPDT_LOOPED: -Slot=2; Loopback exists on Ten-GigabitEthernet2/0/33.
%Dec 21 23:06:53:316 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/5/LPDT_RECOVERED: -Slot=2; Loopback on Ten-GigabitEthernet2/0/33 recovered.
%Dec 21 23:05:23:216 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/4/LPDT_LOOPED: -Slot=2; Loopback exists on Ten-GigabitEthernet2/0/33.
%Dec 21 23:01:53:310 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/5/LPDT_RECOVERED: -Slot=2; Loopback on Ten-GigabitEthernet2/0/33 recovered.
%Dec 21 22:59:23:210 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/4/LPDT_LOOPED: -Slot=2; Loopback exists on Ten-GigabitEthernet2/0/33.
%Dec 21 22:56:53:305 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/5/LPDT_RECOVERED: -Slot=2; Loopback on Ten-GigabitEthernet2/0/33 recovered.
%Dec 21 22:52:53:202 2017 sw-ce-rich-rdj-info-baie_12_13-29 LPDT/4/LPDT_LOOPED: -Slot=2; Loopback exists on Ten-GigabitEthernet2/0/33.

what can i do to check where the loopback is ? (this port is connected to the core network, but i dont have any information on the core about a loop)

i used wireshark on the same vlan to see if i can see the message LPDT on layer 2, but i didnt see anything

how can i debug myself ? any ideas ?

thx a lot for your reply