VLAN Mismatch error eventhough same config

bharathid · ‎03-03-2013

Hi experts,

I am seeing Native VLAN mismatch errors on my 6506 switches as below

SW1

.Mar 4 02:06:37 UTC: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/19 (981), with SW1 GigabitEthernet5/1 (1).

SW2

4y2w: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet5/1 (1), with SW2 GigabitEthernet2/16 (981).

But the switch configurations are same on the respective ports

SW1

interface Port-channel19

switchport

switchport trunk encapsulation dot1q

switchport trunk native vlan 981

switchport trunk allowed vlan 210-212,250-252,254,501,982,985

switchport mode trunk

mls qos trust dscp

end

SW2

interface Port-channel19

switchport

switchport trunk encapsulation dot1q

switchport trunk native vlan 981

switchport trunk allowed vlan 210-212,250-252,254,501,982,985

switchport mode trunk

mls qos trust dscp

end

What will be the issue for VLAN Mismatch error ?

IOS SW1-----Version 12.2(17r)SX5, RELEASE SOFTWARE (fc1)

IOS SW2------Version 12.2(17r)SX3, RELEASE SOFTWARE (fc1)

I have seen the VTP Version on both the switches are varying as below

SW1#sh vtp status

VTP Version : 3 (capable)

Configuration Revision : 0

Maximum VLANs supported locally : 1005

Number of existing VLANs : 70

VTP Operating Mode : Transparent

VTP Domain Name : RX-SERVICES

VTP Pruning Mode : Disabled (Operationally Disabled)

VTP V2 Mode : Disabled

VTP Traps Generation : Disabled

MD5 digest : 0x87 0x75 0xDA 0x56 0xE2 0x61 0x7A 0

Configuration last modified by 192.168.128.44 at 0-0-00 00:00:00

VTP version running : 1

SW2#sh vtp status

VTP Version : 2

Configuration Revision : 0

Maximum VLANs supported locally : 1005

Number of existing VLANs : 17

VTP Operating Mode : Transparent

VTP Domain Name : RX-SERVICES

VTP Pruning Mode : Disabled

VTP V2 Mode : Enabled

VTP Traps Generation : Disabled

MD5 digest : 0xC5 0x09 0x95 0x67 0x61 0xAD 0x17 0x35

Configuration last modified by 192.168.40.11 at 9-4-08 20:23:05

Will it(VTP Version mismatch) be the issue for getting the VLAN Mismatch Error ?

Leo Laohoo · ‎03-03-2013

Post the output to the following commands:

SW1: sh run interface G2/19

SW1: sh run interface G2/16

SW2: sh run interface G5/1

bharathid · ‎03-03-2013

Hi leolaohoo,

The native vlan mismatch b/w the ports are G2/19 on SW1 and G1/5 on Sw2

Here is the config

SW1#sh run int g2/19
Building configuration...

Current configuration : 306 bytes
!
interface GigabitEthernet2/19
switchport
switchport trunk encapsulation dot1q
switchport trunk native vlan 981
switchport trunk allowed vlan 211,212,250-252,254,501,982,985
switchport mode trunk
mls qos trust dscp
channel-group 31 mode active
end

SW2#sh run int g5/1
Building configuration...

Current configuration : 304 bytes
!
interface GigabitEthernet5/1
switchport
switchport trunk encapsulation dot1q
switchport trunk native vlan 981
switchport trunk allowed vlan 210-212,250-252,254,501,982,985
switchport mode trunk
mls qos trust dscp
channel-group 19 mode active
end

Leo Laohoo · ‎03-03-2013

Somethings not right here.

1. If you look at your opening thread, SW1, Gi 2/19 is connected to SW2, Gi 5/1. If you look at SW2, Gi 5/1 it's connected to SW1, Gi 2/16.

2. How "recent" is this? The reason why I'm asking is because your logs do not give me an accurate time. For all I know, this log could be "4y2w"-old.

bharathid · ‎03-03-2013

Hi Leo,

sorry for the confusion,

I have 2 switches (sw2,sw3) connected to Sw1. I am getting VLAN Mismatch error on SW-1 for both sw2 and sw3

This is SW1 log

.Mar 4 05:27:38 UTC: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/19 (981), with SW2 GigabitEthernet5/1 (1).

.Mar 4 05:28:03 UTC: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/16 (981), with SW3 GigabitEthernet5/1 (1).

SW-2

4y0w: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet5/1 (1), with CORP-MTP-RXDST-R1.walgreens.com GigabitEthernet2/19 (981).

SW-3

4y2w: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet5/1 (1), with CORP-MTP-RXDST-R1.walgreens.com GigabitEthernet2/16 (981).

The logs in sw2 and sw3 are not old, it is recently generated. I dont know why the timestamp is showing like this.

Leo Laohoo · ‎03-04-2013

The logs in sw2 and sw3 are not old, it is recently generated. I dont know why the timestamp is showing like this.

That's because your service lines are set to default.

Try this set of commands:

service time d d s l

service time l d s l

clock timezone <+ or - UTC>

clock summer-time recurring ?

I have 2 switches (sw2,sw3) connected to Sw1. I am getting VLAN Mismatch error on SW-1 for both sw2 and sw3

Post the config again for each port including both ports of SW1.

glen.grant · ‎03-03-2013

Look at the ports themselves in the port channel and see if the native vlans do not match on the ports themselves .

InayathUlla Sharieff · ‎03-03-2013

Whenever native Vlan on port-channel is changed, the CDP will use this vlan for the port-channel.

But the Native vlan config is not propogated to member ports of that port-channel. Hence the cdp

packets are sent out of the member ports with the previously configured native vlan.

Conditions:

If " native vlan " is changed on port-channel interface.

Command is : switchport trunk native vlan < native-vlan>

Workaround:

Change the native vlan on member interfaces of port-channel to the same value as of port-ch.

bharathid · ‎03-03-2013

Hi sharieff,

You can see the above configs on the interfaces and portchannels are same, there is no chabge in native vlan no.

InayathUlla Sharieff · ‎03-03-2013

Hi Bharth,

I found a bug for this but this is not affected with the fiimrware which you are running.

This looks to me a strange issue which should not occur. Can you please do the following if this is feasible to you:

Remove the config and re-apply it.

Regards

Inayath

milan.kulik · ‎03-04-2013

Hi,

a) try show int ... switchport

on your sw2 to check the native VLAN operational.

b) As the switches are in VTP transparent mode:

Is the VLAN 981 configured on SW2?

If not, that would explain why VLAN1 remains the native one.

(On the other hand, I'd expect the IOS to reply with an error message when configuring non-existing VLAN as native on the port. But possibly VLAN 981 was removed from the config later?)

HTH,

Milan