%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/1 (169), with SW1 GigabitEthe rnet1/1 (1).

[networkinggeek]

Hi

I just put this question since I am confused how native LANs information is shared,

I have a very simple scenario 

SW1 Gi1/1 (vlan169)<--> SW3 Gi1/1 (no vlan)

What would cause native vlan error to trigger, I see native vlans same on both sides though. What is the actual logic behind that alarm?

To turn this off, what are my all possible options?

Would it solve if I add other port to vlan 106? set it to non-negotiate?

SW1#show int gi1/1 swi
SW1#show int gi1/1 switchport
Name: Gi1/1
Switchport: Enabled
Administrative Mode: dynamic auto
Operational Mode: static access
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: native
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: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL

Protected: false
Appliance trust: none

-------------------

SW3# show int gi1/1 switchport
Name: Gi1/1
Switchport: Enabled
Administrative Mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: negotiate
Operational Trunking Encapsulation: native
Negotiation of Trunking: Off
Access Mode VLAN: 169 (VLAN0169)
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: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL

Protected: false
Appliance trust: none

[Jon Marshall]

Depends what you are trying to do. 

If you want both ports to be access ports in vlan 169 then just set the port on SW3 to be an access port in vlan 169. 

If you want it to be a trunk port then just configure both ends to be a trunk. 

Jon

[networkinggeek]

Yeah I can do that, but what I am trying to find, where is that switch seeing mismatch in native vlans in my scenario? and giving this log message

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/1 (169), with SW1 GigabitEthe       rnet1/1 (1).

[paul driver]

Hello

First of all native vlan isnt switch specific its link specific - as such if you a specified a natvie vlan on one end of the trunk and the other hasnt , then the mistmatch occurs because untagged frames from either side of the link are being seen differently, one side of the trunk is expecting to receive untagged frame in vlan 1 and the other isn't, Or in this case one side is in access port and the other is trying to be a trunk

res
Paul

[networkinggeek]

Hey Paul, So what I get from your response is that my native_vlan_mismatch log is because my one side of port is access and other side is trunk? which is true, but what surprised me was, my native vlans are same on both interfaces as vlan1, so not sure why it prompts me with that log? When I read my log message it seems like its considering 169 as one native vlan, which is not correct.

Sal

[paul driver]

Hello

One an access port and the other is trunk and i am guessing vtp is enabled, thus vtp trying to share information between access-port and trunk.

Try either of these to negate error
1) create trunk either ends
2) disable cdp
3) change vtp domain on either switch to be different

res
Paul

[Jon Marshall · Accepted solution]

One side is not a trunk, look at the operational mode, both are static access. 

All the error message is telling you is that the ports are in different vlans. 

Jon

[networkinggeek]

Well if the alarm log is just telling that the ports are in different vlans and different operational modes then it makes sense, I was thrown off with the native_vlan part in the log, and made me think where the mismatch is :)