Native VLAN mismatch error

Unanswered Question
Aug 25th, 2008

Hi,

In my Core switch I am getting native vlan mismatch error on the port which is connected to access switch.From the access switch its connected to Cisco ASA.In the access switch nothing is configured.please find the logs and configuration..

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet3/1 (50), with Switch GigabitEthernet0/4 (1).

Regards,

som

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johnakeating Mon, 08/25/2008 - 20:40

check the native vlan on your trunk ports make sure they are the same vlan.

somnath21 Mon, 08/25/2008 - 21:20

sorry, I didn't get..that port in the core switch is configured as a access port.

Jon Marshall Tue, 08/26/2008 - 00:37

If there is no configuration on the access switch then by default all ports will be in vlan 1, but gi3/1 on your core switch is in vlan 50. So you have 2 options

1) Create vlan 50 on the access switch and assign gi0/4 and any other ports such as the firewall into that vlan. Be aware that because all ports are in vlan 1 at the moment that any ports that communicate with each other on the access switch will need to be moved to vlan 50.

2) Put gi3/1 on your core switch into vlan 1.

Jon

nramesh25 Tue, 08/26/2008 - 01:34

no Jon, 3 options...

3)you can configure both the ports as trunk as it will very helpful to configure other VLANs on access switch.

Jon Marshall Tue, 08/26/2008 - 04:45

Ramesh

Based on the original posters configuration that is not an option because he does not want it to be a trunk - see the OP's attached configs for details.

Of course if he did want a trunk this would be an option but telling him to make it a trunk link without fully understanding his topology is not something i wanted to do.

Jon

Jason Fraioli Tue, 08/26/2008 - 05:10

Why not do away with the interface vlan 50, and just make gig3/1 a routed interface?

Jon Marshall Tue, 08/26/2008 - 05:19

Jason

That could be an option but again it depends on the full topology. For example there could be a pair of ASA firewalls that connect to separate access switches and then connect back to separate core switches. In which case the inside interfaces on the firewalls would have to be in the same vlan for failover. So you couldn't use routed ports.

I really only wanted to give options that were specific to his configs but i agree if it was a single connection to a single firewall and nothing else on the 6500 switch or any other switches connected to the 6500 needed to be in vlan 50 then yes this is a good option.

Jon

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