Spanning Tree and Trunk port

[bkyuksel]

Hi guys,

Today I had an issue with trunking between switches. I am not used to use spanning tree protocols too much but in current config they have spanning tree enabled on core and access switches. Once I change both ports to trunk on core and access I received the below error and ports are not even blinking at all no amber light no green nothing. Just disabled. I think this is spanning tree related and I need some help here SPANNING TREE EXPERS ARE WELCOME 

Here is the error below;

%LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to up
%SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non trunk FastEthernet0/1 VLAN172.
%SPANTREE-7-BLOCK_PORT_TYPE: Blocking FastEthernet0/1 on VLAN0172. Inconsistent port type.

[M02@rt37]

Hello @bkyuksel,

The error message you received indicates an inconsistency in the port type for VLAN 172. The switch has detected a BPDU with 802.1Q tagging on the non-trunk interface FastEthernet0/1, which is causing the port to be blocked by spanning tree protocol.

Check the trunk configuration on both the core and access switches. Ensure that the appropriate interfaces are configured as trunk ports, allowing the desired VLANs, including VLAN 172, to pass through. Make sure the trunk configuration matches on both ends of the link.

[bkyuksel]

Hi, thanks for the reply. I am %100 percent sure that the trunking configuration is done how it is supposed to be. But there is something weird with the spanning tree protocol.

[M02@rt37]

Hello @bkyuksel,

Please do

#sh spanning-tree vlan 172

#sh spanning-tree interface FastEthernet0/1

#sh logging | include STP

Share the output here please.

[Flavio Miranda]

Hello @bkyuksel 

 This bahavior is expect when we connect a trunk port to an access port.

 This could be reproducable if you have the chance.

[MHM Cisco World]

Show interface x/x switch

Share this for both SW

[bkyuksel]

sw1(config)#do sh spanning-tree summary
Switch is in rapid-pvst mode
Root bridge for: none
EtherChannel misconfig guard is enabled
Extended system ID is enabled
Portfast Default is disabled
PortFast BPDU Guard Default is enabled
Portfast BPDU Filter Default is disabled
Loopguard Default is disabled
UplinkFast is disabled
BackboneFast is disabled
Configured Pathcost method used is short

Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
Total 0 0 0 0 0

Also I have this.

Gi1/0/50 sw1 notconnect 1 auto auto 1000BaseSX SFP

[MHM Cisco World]

Show interface x/x switch <<- I need to see output of this 

[bkyuksel]

ISSUE RESOLVED: it was due to an old SFP module on the old switch. it was integrated one and it was not compatible to new switch despite of being original one.

[MHM Cisco World]

the operation is down 
cable not connect or you no shut the port 

[bkyuksel]

I did the no shutdown and shutdown and no shutdown several times. And I am sure that it is connected to the related port.

[MHM Cisco World]

this lab of PKT ?

[bkyuksel]

Unfortunately it is real life