native vlan mismatch

[RMAKing]

I have a Cisco 3550 connected to a Cisco 4506. I am getting errors of native vlan mismatch between the two. Traffic is flowing fine but I can't access the 3550 (the one with the misconfigured VLAN) because I'm getting an authentication error, even at the console (using TACACS). Any ideas on least obtrusive way to get into switch?

 

[fmonteiro]

I would correct the native vlan mismatch. The message means you have different native vlan values for both devices. i have already had some problems with this. Check the native vlan in the 4506 (sh vlan), and configure the 3550 accordingly.

 

[RevFlash]

My native vlan is set to 180 I think it should be set to 1 (like) all the other trunks:

Console> (enable)show trunk
* - indicates vtp domain mismatch
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
2/19 on dot1q trunking 180
2/20 on dot1q trunking 1

Yes I have bigger problems...
Anyways how do I get the Native back to 1 here,
what are the commands from the 4006 console?

 

[fmonteiro]

I am almost sure this is our problem:
When connecting Cisco switches through an 802.1Q trunk, make sure the native VLAN for an 802.1Q trunk is the same on both ends of the trunk link. If the native VLAN on one end of the trunk is different from the native VLAN on the other end, spanning tree loops might result.

Our problem could be at the 3550 side. On this switch, enter the following command on the interface configured as the 802.1q trunk:

switchport trunk native vlan 1

On the 4006 you may also try the following commands:
clear trunk 2/19 180
set trunk 2/19 1

If this does not solve he problem, or this is not the case, please post the config files for both equipments.

You may as well take a look at the following document:
Configuring 802.1q Trunking Between a Catalyst 3550 and Catalyst Switches Running Integrated Cisco IOS (Native Mode)

http://www.cisco.com/warp/customer/473/88.html

 

[RevFlash]

Clear trunk 180
that command clears "Vlans allowed on trunk"

I am trying to set the NATIVE vlan to 1 rather than 180
as I have a vlan mismatch ....
See below:

4006Console> (enable) show trunk 3/17
* - indicates vtp domain mismatch
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
3/17 auto dot1q trunking 180

Port Vlans allowed on trunk
-------- ---------------------------------------------------------------------
3/17 1
4006Console> (enable) show logging buffer -50

2003 Jul 21 08:42:11 %SPANTREE-2-RX_1QNON1QTRUNK: Rcved 1Q-BPDU on non-1Q-trunk
port 3/17 vlan 180
2003 Jul 21 08:42:11 %PAGP-5-PORTTOSTPort 3/17 joined bridge port 3/17
2003 Jul 21 08:42:11 %SPANTREE-2-RX_1QNON1QTRUNK: Rcved 1Q-BPDU on non-1Q-trunk
port 3/17 vlan 180
2003 Jul 21 08:42:12 %SPANTREE-2-RX_1QNON1QTRUNK: Rcved 1Q-BPDU on non-1Q-trunk
port 3/17 vlan 180
2003 Jul 21 08:42:12 %SPANTREE-2-RX_BLKPORTPVID: Block 3/17 on rcving vlan 180 f
or inc peer vlan 1
2003 Jul 21 08:43:32 %CDP-4-NVLANMISMATCH:Native vlan mismatch detected on port
3/17
2003 Jul 21 08:45:32 %PAGP-5-PORTFROMSTPort 3/17 left bridge port 3/17
2003 Jul 21 08:45:35 %DTP-5-TRUNKPORTONort 3/17 has become dot1q trunk
2003 Jul 21 08:45:47 %PAGP-5-PORTTOSTPort 3/17 joined bridge port 3/17
4006Console> (enable)


2950#show logging
Syslog logging:
Log Buffer (4096 bytes):
_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (1), with JA
B0442008R 3/17 (180).
4d20h: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEther
net0/24 (1), with JAB0442008R 3/17 (180).
4d20h: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/24 on VLAN0180
. Port consistency restored.
4d20h: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/24 on VLAN0001
. Port consistency restored.

6d01h: %EC-5-L3DONTBNDL1: Fa0/24 suspended: PAgP not enabled on the remote port.

2950#show vlan

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/24
10 VLAN0010 active
150 VLAN0150 active
168 VLAN0168 active
180 VLAN0180 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
2950# show running-config (some omited)
interface FastEthernet0/23
switchport access vlan 180
no ip address
!
interface FastEthernet0/24
switchport mode trunk
no ip address
duplex full
speed 100
channel-group 1 mode desirable
!
interface Vlan1
ip address 192.9.254.13 255.255.255.0
no ip route-cache
!
interface Vlan180
no ip address
no ip route-cache
shutdown
!
ip default-gateway 192.9.254.254
ip http server

 

[jah3000]

You should just put your ip info on Vlan 180. First, shut down interface vlan 1, then put your ip address on interface vlan 180 and make that interface active with the command no shut.

 

[jah3000]

On the 4000 switch, turn the trunk off on 3/17(set trunk 3/17 off dot1q). Then add 3/17 to vlan 1(set vlan 1 3/17). this will make it's native vlan 1. then turn the trunk back on(set trunk 3/17 on dot1q) and your problem should be solved.