Native VLAN mismatch error on access port

[vincent.munier]

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

[lgijssel · Accepted solution]

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

[Lei Tian]

Hi,

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

Regards,

Lei Tian

[vincent.munier]

Hi,

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

Regards

[Lei Tian]

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

[vincent.munier]

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

[cadet alain]

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.

[vincent.munier]

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.

[vincent.munier]

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

[glen.grant]

  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.

[vinayjaiswal]

Hi,

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

Thanks.!

[GarryWhardaya31296]

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

[TheGeekGuy]

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

[Kamal]

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

[solasolent1988]

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