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Replies

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

1 Accepted Solution

Accepted Solutions

lgijssel
Level 9
Level 9

When you give the messages a second look, you will notice they are sourced by the cdp protocol.

In  circumstances like this, where you are sure the mismatch is not a real problem, you may consider to disable cdp for those interfaces.

That would be a (somewhat dirty) workaround.

Another solution is to make the vlan numbers match. This requires more work but it would be the best solution.

regards,

Leo

View solution in original post

15 Replies 15

lgijssel
Level 9
Level 9

When you give the messages a second look, you will notice they are sourced by the cdp protocol.

In  circumstances like this, where you are sure the mismatch is not a real problem, you may consider to disable cdp for those interfaces.

That would be a (somewhat dirty) workaround.

Another solution is to make the vlan numbers match. This requires more work but it would be the best solution.

regards,

Leo

Hi,

That check is added in cdp v2, you can disable it by "no cdp advertise-v2" under global configuration mode.

Regards,

Lei Tian

Hi,

I've tried to disable v2 cdp advertissements, but it does not change. It would've been a good solution.

Regards

Hi,

I tested it on 3560 with 12.2(35)SE2; it is working as expected.

before disable cdp v2

4d02h: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet0/14 (20), with sw2 GigabitEthernet0/14 (1).
4d02h: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet0/14 (20), with sw2 GigabitEthernet0/14 (1).

sw1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
sw1(config)#no cdp advertise-v2

sw1#sh cdp
Global CDP information:
        Sending CDP packets every 60 seconds
        Sending a holdtime value of 180 seconds
        Sending CDPv2 advertisements is not enabled

no more mismatch message.

Regards,

Lei Tian

Hi,

I've done the same:

r3s04#sh cdp
Global CDP information:
        Sending CDP packets every 60 seconds
        Sending a holdtime value of 180 seconds
        Sending CDPv2 advertisements is not enabled
r3s04#

But there's no change, i always have the messages in the log:

Dec 10 07:44:35: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).
Dec 10 07:45:35: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with ris12.gie.intra FastEthernet0/2 (301).

I think cdp implementation is not exactly the same between a 3560 et an "old" 2950. I'm running with Version 12.1(22)EA11

Regards

Vincent

Hi,

The 2 switchs are not on the same vtp domain so the uplink between the 2 switchs in access mode

You can make the link a trunk even between 2 different VTP domains.

Don't forget to rate helpful posts.

Yes of course, but i've used  acces mode because my vlan 1 on switch 1 is not the same vlan than the vlan 1 on switch 2.

Thanks.

Thanks. It's a shame to have to disable cdp for that, but i'll do it because i can't easily migrate my vlan 1 in vlan 301.

Vincent

  It would take all of 5 minutes to reconfigure the 2950 in vlan 1 .  Create vlan 301  on the 2950 , use the interface range command to change all the ports into vlan 301 and create a new SVI for vlan 301 to manage the switch  and shutdown the vlan 1 SVI .  You would have to do this from the console though unless you have a tftp server and the current config file in which case you could just modify the current config file download it to startup and reload.

Hi,

 

I tried it on Cisco 6500 switch for same native vlan mismatch issue and It got fixed.

 

Thanks.!

 

 

Does that mean it's cdp's fault? Like bug?

TheGeekGuy
Level 1
Level 1

 

It is not possible the communication between two devices in different vlans using a access link.

You should configure one port as mode trunk and in the other link as a dynamic desirable.

 

Some questions:

 

Do one of your switches operate in layer 3?

Are you using a router on a stick? 

 

Switch 2 (HOST 2)

 

conf ter

interface f0/2

switchport mode trunk

switchport trunk allowed vlan 1-1005 // in this case will cover the vlan1 and 301

no shutdown

 

Switch 1 (Host 1)

interface f0/1

switchport mode dynamic desirable

no shutdown

 

 

Regards,

 

The Geek Guy

This did solve the problem:

 

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (4), with Switch GigabitEthernet0/1 (1)

 

S1(config-if)#switchport trunk encapsulation dot1q

S1(config-if)#switchport mode trunk

did solved it for me i dont know why can you explain
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