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Native VLAN mismatch error on access port

vincent.munier
Level 1
Level 1

Hi,

I have 2 hosts (on 2 switches)  that communicate wich each other.

host 1 is in the vlan 1 and host 2 is in the vlan 301. The 2 switchs are not on the same vtp domain so the uplink between the 2 switchs in access mode.

It's working whitout problems but i have errors in the log:

Dec  9 14:08:21: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).

Dec  9 14:09:21: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).

Dec  9 14:10:21: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).

Dec  9 14:11:21: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).

Dec  9 14:12:21: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).

Dec  9 14:13:21: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).

I don't understand why i have natvie vlan mismatch when i user acces ports and not trunk ports?

This is the config of the uplinks ports:

ris12#sh run int fa 0/2

Building configuration...

Current configuration : 148 bytes

!

interface FastEthernet0/2

description dmz financier vers rifw05

switchport access vlan 301

switchport mode access

speed 100

duplex full

end

ris12#sh int fa0/2 switchport

Name: Fa0/2

Switchport: Enabled

Administrative Mode: static access

Operational Mode: static access

Administrative Trunking Encapsulation: dot1q

Operational Trunking Encapsulation: native

Negotiation of Trunking: Off

Access Mode VLAN: 301 (VLAN0301)

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: ALL

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

ris12#

*************
r3s04#sh run int fa 0/1
Building configuration...
Current configuration : 123 bytes
!
interface FastEthernet0/1
description RIFW05 via switch tranceiver
switchport mode access
speed 100
duplex full
end
r3s04#sh int fa 0/1 switchport
Name: Fa0/1
Switchport: Enabled
Administrative Mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: native
Negotiation of Trunking: Off
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: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Appliance trust: none
r3s04#

Thanks for your help!

Vincent

Dessin1.gif

15 Replies 15

I'm not entirely sure what is this referring to, but making a trunk link between switches eliminates the native vlan mismatch when using access port between switches since the trunks allow sending tagged (802.1Q tags) traffic (for each specific VLAN) with VLAN 1 being native by default (therefore untagged) - and that's the reason you don't see the native vlan mismatch if you do not configure it manually to differ.

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