Fixing VLAN mismatch error

[e-montagnino]

I have an incorrectly switch causing VLAN mismatch log entries.

Basically VLAN1 should have been shutdown and the management IP configured on VLAN13. However the IP was put on VLAN1 instead. I have put a temp IP address on VLAN13 (same subnet) but I cannot enable the interface.

Is there some way I can remotely enable VLAN13 and disable VLAN1? I have tried setting up a cluster and use rcommand but I cannot add the problem swtich to the cluster.

Thank you.

[mahmoodmkl]

HI

I think u r using a layer 2 switch i mean 2900 like that. in that u can only have one vlan interface configured at a time.ie at a time only one interface will be active.as far as vlan mismatch error is concern if u r using trunk links verify that u have the same native vlan on the trunk ports.

Thanks

Mahmood

[e-montagnino]

Yes the problem switch is a 2900XL(4MB memory). It is connected to a 3550 series switch. The switches are NOT trunking. Sorry for leaving that out.

I guess I am looking for creative way to fix the problem remotely. Rebooting the switch is an option if that helps.

[Bobby Thekkekandam]

If you configure the other VLAN interface with an address in the same subnet, you're going to get an error message"x.x.x.x overlaps with VLAN1"

Unfortunately, I don't think there's a way to accomplish this remotely. If the link was a trunk, you could readdress vlan1 to the right subnet for that vlan, then telnet back in, and configure Vlan3 with the right address, which would then shut vlan1 down.

HTH,

Bobby

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[lizhing1972]

If you dont have a reachable IP, the only way to remote access is dial in the console port. Hope this helps.

[e-montagnino]

OK I got out to the switch and was able to set the management IP to VLAN13 and shutdown VLAN1. However I am still seeing the following messages in the 2924XL:

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (0), with cat3550a FastEthernet0/1 (13)

Both the 2924XL and the 3550 are not trunked. All ports on both switches are configured are assigned to VLAN13. I am confused as to the 2924XL and the VLAN 0 error.

The 2924XL is running Version 11.2(8.12)SA6 which I think is the latest for the 4MB models. The 3550 is running Version 12.1(13)EA1a.

[Bobby Thekkekandam]

Could you post a "show vlan" from the 2924XL?

thanks,

Bobby

[e-montagnino]

I hope this all wraps ok. Basically, all ports assigned to VLAN13 and no indication of a VLAN0.

VLAN Name Status Ports

---- -------------------------------- --------- -------------------------------

1 default active

13 VLAN0013 active Fa0/1, Fa0/2, Fa0/3, Fa0/4,

Fa0/5, Fa0/6, Fa0/7, Fa0/8,

Fa0/9, Fa0/10, Fa0/11, Fa0/12,

Fa0/13, Fa0/14, Fa0/15, Fa0/16,

Fa0/17, Fa0/18, Fa0/19, Fa0/20,

Fa0/21, Fa0/22, Fa0/23, Fa0/24

1002 fddi-default active

1003 token-ring-default active

1004 fddinet-default active

1005 trnet-default active

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------

1 enet 100001 1500 - - - - - 1002 1003

13 enet 100013 1500 - - - - - 0 0

1002 fddi 101002 1500 - - - - - 1 1003

1003 tr 101003 1500 1005 0 - - srb 1 1002

1004 fdnet 101004 1500 - - 1 ibm - 0 0

1005 trnet 101005 1500 - - 1 ibm - 0 0

[Bobby Thekkekandam]

Hi,

I found a bug that you are running into, CSCec50124.

The 3550 is advertising its vlan as 1 via CDP on this access port. The Cat2900XL does not advertise a vlan at all. The Cat2900XL code that compares the native vlans should not compare them in this case.

The good news is that the bug has been fixed, but the bad news is that the code that has the fix requires 8MB of memory.

However, this is cosmetic, as the underlying problem is a CDP issue. You can either ignore the messages, set your logging level such that they are not logged, or disable CDP.

HTH,

Bobby

*Please rate helpful posts.

[e-montagnino]

Bobby,

Thanks for the information! I will look into adjusting the logging for the 2924.

[misramanish]

I had a very similar issue with vlan error mismatch messages coming on my 6509 that was connected to a 3548 switch. We fixed the issue by typing "switchport access vlan #" on the ethernet port that was uplinking to the 6509.

Originally, 3548 uplink port was on VLAN 1 and 6509 was on a different VLAN. The connection worked and traffic was passing through but for the error messages. If both the uplink ports on your 2924 and 3500 are set to the same vlan IDs, the error msg. should go away.

Let us know if this helps.

[e-montagnino]

Thanks for the suggestion. However, the ports are correctly configured on both switches and the 2924 insists that it's own faste0/1 is on VLAN 0.

You can read the previous posts to review the details but I think Bobby got it figured out with the CSCec50124 report.

Thanks again.