Please excuse my ignorance & noobishness.

I have a switch which has two different point to point connections, these both plug into access ports & have their own VLAN.

These two point to point connections are coming from the same ISP which is causing the port to close.

I'm no expert in spanning-tree loops, and I'm scared of causing any issues. How should I manage these ports? Or is something my ISP has to handle?

*Mar 15 03:58:23 UTC: %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non trunk GigabitEthernet1/0/1 VLAN2050.
*Aug 15 03:58:23 UTC: %SPANTREE-7-BLOCK_PORT_TYPE: Blocking GigabitEthernet1/0/1 on VLAN2050. Inconsistent port type.
*Aug 15 03:58:24 UTC: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/1, changed state to up
*Aug 15 03:58:25 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/1, changed state to up
*Aug 15 03:58:39 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/1, changed state to down
*Aug 15 03:58:40 UTC: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/1, changed state to down

Thank you for your help, totally clueless over here.

  • 1
    This sounds like an ISP question: why are they sending BPDUs at all?
    – Ricky
    Mar 16, 2015 at 8:05
  • I just want to say that I see that nobody gave an answer to this poor soul in distress. And I do not have the answer either. but if I can tell you that the problem is due to an inconsistency in the configuration modes of the port encapsulation. The other end of the ISP is not using equipment compatible with yours and therefore needs to be applied to one of the 2 sides, so that the problem can be solved. When I have a better answer I will return.
    – nameado
    Apr 10, 2018 at 19:02
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer.
    – Ron Maupin
    Jan 6, 2021 at 2:16

1 Answer 1


In my opinion, you've set things up "wrong". (and so has the ISP)

Never, EVER, trust what the ISP puts on your link. If you're running a metro-e interface into a switch, everything possible should be shut off on that port -- VTP, CDP, LLDP, spanning-tree, etc. The ISP isn't part of your "enterprise", so there's no reason to exchange such information with them. Plus, CDP/LLDP will attempt to ensure port settings (including VLAN assignments) are the same.

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