VLAN_MISMATCH_iSSUE

[andrew_xfeel]

Hi ! I've  got following problem within switches in my company, I try to connect to trunk catalyst switch 2950-g but unfortunately I get inconsistent peer vlan message and stp blocks ports on my switch as well as on core one. That leads to some link drops and problems with communication among servers, anyway look at the attached graphic file:

Explanation:

We have a couple of buildings placed too far to be reached by anything, so we try to connect them by using ubiquiti wireless equipment. So basically, the most of the hard work is done, Ap antennas Ubiquiti power Beam are placed on the top of the roof of the highest building, they are connected to unifi switch with sfp fiber, and from there to our main building  to another unifi switch, and then there is an uplink to our core switch SG-500x.

When I configure interface fa0/46 on switch_d as a trunk with standard native vlan1, and connect it to port with the same trunk configuration on my main switch_1 (catalyst 3560-x) it behaves as expected, i.e there is no vlan mismatch. However when I do exactly the same, but with usage of antenna, I'm given the following information:(this info is on all switches due to stp changes in network)

%LINK-3-UPDOWN: Interface GigabitEthernet0/4, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/4, changed state to up
 %SYS-5-CONFIG_I: Configured from console by admin on vty0
 %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/4, changed state to down
 %LINK-3-UPDOWN: Interface GigabitEthernet0/4, changed state to down
 %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 1 on Port-channel1 VLAN9.
 %SPANTREE-2-BLOCK_PVID_PEER: Blocking Port-channel1 on VLAN0001. Inconsistent peer vlan.
: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking Port-channel1 on VLAN0009. Inconsistent local vlan.

and when i immidiatelly plug the cable out..
 %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel1 on VLAN0001. Port consistency restored.
 %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel1 on VLAN0009. Port consistency restored.

switch_1#sh interfaces port-channel 1 switchport
Name: Po1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Administrative Native VLAN tagging: enabled
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk Native VLAN tagging: enabled
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk associations: none
Administrative private-vlan trunk mappings: none
Operational private-vlan: none
Trunking VLANs Enabled: 1-39,50,111,114,170,199,260
Pruning VLANs Enabled: 2-1001

Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none

Whereas on the switch_2 - the remote switch:

switch_2 - END REMOTE SWITCH

%LINK-3-UPDOWN: Interface FastEthernet0/46, changed state to up
%SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 9 on FastEthernet0/46 VLAN1.
%SPANTREE-2-BLOCK_PVID_PEER: Blocking FastEthernet0/46 on VLAN0009. Inconsistent peer vlan.
%SPANTREE-2-BLOCK_PVID_LOCAL: Blocking FastEthernet0/46 on VLAN0001. Inconsistent local vlan.
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/46, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/46, changed state to down
%LINK-3-UPDOWN: Interface FastEthernet0/46, changed state to down

SWITCH_2#sh inter fa 0/46 switchport
Name: Fa0/46
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: down
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: 1-39
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none

Can you help me in resolving this issue ? I don't know why it is happening. Antennas are set as transparent, so they don't do anything special.

Regards,

Andrew

[Julio E. Moisa]

Hi

Is there any provider in the middle? 

Could you pleas share the config?

Thank you 

[andrew_xfeel]

Hi ! I guess I've found it.    (NO PROVIDER HERE - you asked)

On my core stack (consists of 3 switches)I have  sth like this

interface Port-channel2
description LAGSWUNIFI
switchport trunk allowed vlan add 2-3,20-23
switchport trunk native vlan 9

So whenever there is a problem or you see issues like that, try to find the spanning tree root and identify the configuration on that main root. In this case, Ubiquiti Unify switch is directly aggregated into sg500x stack switch on interface po2.

I''ll try to verify tommorow and set the trunk port with native vlan9 on switch_2, will write if it helps.

What I don't know is what to do with other switches, that still have native vlan set to default 1, I have a bunch of them.

Please verify if my theory is good and that it might be the solution. 

[andrew_xfeel]

Hi ! Still no luck,

I've setup fa0/1 as trunk 

switchport trunk native vlan9

switchport mode trunk

switchport trunk allowed vlan 2,3,9,2-23,

and  when I've attached antenna on one side to my trunk port in a switch_2, on my stack switch on the other side I get the warning: 

%CDP-W-NATIVE_VLAN_MISMATCH: Native VLAN mismatch detected on interface gi3/1/13.

Whereas on my end switch_2 there was no info about mismatch

I put the cable out immidiatelly.  I didn't want stp block and mess in my network. It would be a nightmare. 

Interface gi3/1/13 is setup itself as trunk, with administrative and operational vlan as 1, but as part of a lag it is setup like this:

Administrative VLANs:	2T, 3T, 9UP, 20T, 21T, 22T, 23T
Operational VLANs:	2T, 3T, 9UP, 20T, 21T, 22T, 23T

  in my switch sg500x,

see the attached file from my previous post

Any guess ?

Please Help

[dperezoquendo]

Hello,

Did you also configure fa0/1 into an Etherchannel when you set up as a trunk? Anyways, try following:

1. Allocate another vlan for native vlan. I don't like how you're native vlan has an SVI though I'm not sure if that is causing issues. Usually the native vlan is just a "dummy" vlan to help establish the trunk and increase a bit of security as you're not using the default vlan 1.
2. Build port-channel 2 on switch_2. Unsure if you did that or not. It appears gi3/1/13 on your stack switch is using port-channel 2

For example, maybe try following configurations:

Switch_2

 vlan 999

   name NATIVE_VLAN

 int f0/1

 channel-group mode 2 auto

 int po2

  switchport mode trunk

  switchport trunk native vlan 999

  switchport trunk allowed vlan ## 

Stack_Switch

vlan 999

 name NATIVE_VLAN

int po2

 switchport trunk native vlan 999