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VLAN Mismatch

Good luck with this one. We are getting a native VLAN mismatch and the native VLAN is the same on both 3750's:

We are getting the following logging on 3750-1:

Jul 29 01:12:43: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on
GigabitEthernet1/0/1 (620), with 3750-2 GigabitEthernet1/0/12 (1).
Jul 29 01:13:43: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on
GigabitEthernet1/0/1 (620), with Trent_Fibre GigabitEthernet1/0/12 (1).
Jul 29 01:14:43: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on
GigabitEthernet1/0/1 (620), with Trent_Fibre GigabitEthernet1/0/12 (1).
Jul 29 01:15:43: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on
GigabitEthernet1/0/1 (620), with Trent_Fibre GigabitEthernet1/0/12 (1).
Jul 29 01:16:43: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on
GigabitEthernet1/0/1 (620), with Trent_Fibre GigabitEthernet1/0/12 (1).

Here is the config for 3750-1:

VLAN Name                             Status    Ports
---- -------------------------------- --------- ------------------------------
1    default                          active    Fa1/0/3, Fa1/0/4, Fa1/0/5
                                                Fa1/0/6, Fa1/0/8, Fa1/0/9
                                                Fa1/0/10, Fa1/0/11, Fa1/0/12
                                                Fa1/0/13, Fa1/0/14, Fa1/0/15
                                                Fa1/0/16, Fa1/0/17, Fa1/0/18
                                                Fa1/0/19, Fa1/0/20, Fa1/0/21
                                                Fa1/0/22, Fa1/0/23, Gi1/0/2
72   VLAN0072                         active    Fa1/0/1, Fa1/0/2
202  VLAN0202                         active    Fa1/0/24
620  Data                       active    Fa1/0/7
621  Voice                      active
1002 fddi-default                     act/unsup
1003 token-ring-default               act/unsup
1004 fddinet-default                  act/unsup
1005 trnet-default                    act/unsup

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1    enet  100001     1500  -      -      -        -    -        0      0
72   enet  100072     1500  -      -      -        -    -        0      0
202  enet  100202     1500  -      -      -        -    -        0      0
620  enet  100620     1500  -      -      -        -    -        0      0
621  enet  100621     1500  -      -      -        -    -        0      0
1002 fddi  101002     1500  -      -      -        -    -        0      0
1003 tr    101003     1500  -      -      -        -    -        0      0
1004 fdnet 101004     1500  -      -      -        ieee -        0      0
1005 trnet 101005     1500  -      -      -        ibm  -        0      0

Remote SPAN VLANs
------------------------------------------------------------------------------


Primary Secondary Type              Ports
------- --------- ----------------- ------------------------------------------

3750-1#
3750-1#
3750-1#
3750-1#sh int trunk

Port        Mode         Encapsulation  Status        Native vlan
Gi1/0/1     on           802.1q         trunking      1

Port        Vlans allowed on trunk
Gi1/0/1     1-4094

Port        Vlans allowed and active in management domain
Gi1/0/1     1,72,202,620-621

Port        Vlans in spanning tree forwarding state and not pruned
Gi1/0/1     1,72,202,620-621

Here is the config on 3750-2:

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi1/0/5, Gi1/0/6, Gi1/0/7
                                                Gi1/0/8, Gi1/0/9, Gi1/0/10
                                                Gi1/0/11
620  Data                       active
621  Voice                      active
1002 fddi-default                     act/unsup
1003 token-ring-default               act/unsup
1004 fddinet-default                  act/unsup
1005 trnet-default                    act/unsup

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1    enet  100001     1500  -      -      -        -    -        0      0
620  enet  100620     1500  -      -      -        -    -        0      0
621  enet  100621     1500  -      -      -        -    -        0      0
1002 fddi  101002     1500  -      -      -        -    -        0      0
1003 tr    101003     1500  -      -      -        -    -        0      0
1004 fdnet 101004     1500  -      -      -        ieee -        0      0
1005 trnet 101005     1500  -      -      -        ibm  -        0      0

Remote SPAN VLANs
------------------------------------------------------------------------------


Primary Secondary Type              Ports
------- --------- ----------------- ------------------------------------------

3750-2#
3750-2#
3750-2#sh int trunk

Port        Mode         Encapsulation  Status        Native vlan
Gi1/0/1     auto         n-802.1q       trunking      1
Gi1/0/2     auto         n-802.1q       trunking      1
Gi1/0/3     on           802.1q         trunking      1
Gi1/0/4     on           802.1q         trunking      1
Gi1/0/12    on           802.1q         trunking      1

Port      Vlans allowed on trunk
Gi1/0/1     1-4094
Gi1/0/2     1-4094
Gi1/0/3     1-4094
Gi1/0/4     1-4094
Gi1/0/12    1-4094

Port        Vlans allowed and active in management domain
Gi1/0/1     1,620-621
Gi1/0/2     1,620-621
Gi1/0/3     1,620-621
Gi1/0/4     1,620-621
Gi1/0/12    1,620-621

Port        Vlans in spanning tree forwarding state and not pruned
Gi1/0/1     1,620-621
Gi1/0/2     1,620-621
Gi1/0/3     1,620-621
Gi1/0/4     1,620-621
Gi1/0/12    1,620-621

Please let me know what you think.

4 REPLIES
Cisco Employee

Re: VLAN Mismatch

Hello,

Can you please post the running configuration from both ports in question

here?

Regards,

NT

New Member

Re: VLAN Mismatch

interface GigabitEthernet1/0/1
description link to fibre switch
switchport trunk encapsulation dot1q
switchport mode trunk
end

interface GigabitEthernet1/0/12
switchport trunk encapsulation dot1q
switchport mode trunk
end

Cisco Employee

Re: VLAN Mismatch

Hello,

Thanks for the outputs. Are you still getting those error messages or did

they stop? If you are not getting those error messages anymore, can you

check your logs to see if somebody made any changes to the configuration

during the period?

Regards,

NT

New Member

Re: VLAN Mismatch

Actually, dont worry. I double checked the time and date

again and it was when we made some configuration changes. Thanks for your help.

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