STP not blocking with native VLAN mismatch

I'm currently working on the 802.1Q Native VLAN lab (http://labs.ine.com/workbook/view/rs-v5-workbook/task/802-1q-native-vlan-MTk4Mg== ) and seeing behavior I don't understand.  Specifically, I do not see STP blocking ports on native VLAN mismatch and my ports are flapping.

 

I have 4 WS-C3560-24TS switches running 15.0(2)SE C3560-IPSERVICESK9-M.  The output of the verification steps for my switches is as follows.

 

SW1#show int trunk

Port        Mode             Encapsulation  Status        Native vlan
Fa0/19      desirable        802.1q         trunking      146
Fa0/20      desirable        802.1q         trunking      146
Fa0/21      desirable        802.1q         trunking      146
Fa0/22      desirable        802.1q         trunking      146
Fa0/23      desirable        802.1q         trunking      146
Fa0/24      desirable        802.1q         trunking      146

Port        Vlans allowed on trunk
Fa0/19      1-4094
Fa0/20      1-4094
Fa0/21      1-4094
Fa0/22      1-4094
Fa0/23      1-4094
Fa0/24      1-4094

Port        Vlans allowed and active in management domain
Fa0/19      1
Fa0/20      1
Fa0/21      1
Fa0/22      1
Fa0/23      1
Fa0/24      1

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/19      1
Fa0/20      1
Fa0/21      1
Fa0/22      1
Fa0/23      1
Fa0/24      1

SW2#show int tru

Port        Mode             Encapsulation  Status        Native vlan
Fa0/23      auto             n-802.1q       trunking      146
Fa0/24      auto             n-802.1q       trunking      146

Port        Vlans allowed on trunk
Fa0/23      1-4094
Fa0/24      1-4094

Port        Vlans allowed and active in management domain
Fa0/23      1
Fa0/24      1

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/23      1
Fa0/24      none

SW3#show int tru

Port        Mode             Encapsulation  Status        Native vlan
Fa0/19      auto             n-802.1q       trunking      146
Fa0/20      auto             n-802.1q       trunking      146

Port        Vlans allowed on trunk
Fa0/19      1-4094
Fa0/20      1-4094

Port        Vlans allowed and active in management domain
Fa0/19      1
Fa0/20      1

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/19      1
Fa0/20      none

SW4#show int tru

Port        Mode             Encapsulation  Status        Native vlan
Fa0/21      auto             n-802.1q       trunking      146
Fa0/22      auto             n-802.1q       trunking      146

Port        Vlans allowed on trunk
Fa0/21      1-4094
Fa0/22      1-4094

Port        Vlans allowed and active in management domain
Fa0/21      1
Fa0/22      1

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/21      1
Fa0/22      none

 

 

When I change the default vlan on SW1 FA0/23 and FA0/24, I get CDP messages indicating native VLAN mismatch, but I do not see messages indicating that STP is blocking for that reason.  Show spanning-tree inconsistent ports also shows nothing.  However, on SW1 ports FA0/23 and FA0/24 no longer appear as forwarding and not pruned in the show interface trunk output.

 

SW1#show int trunk

Port        Mode             Encapsulation  Status        Native vlan
Fa0/19      desirable        802.1q         trunking      146
Fa0/20      desirable        802.1q         trunking      146
Fa0/21      desirable        802.1q         trunking      146
Fa0/22      desirable        802.1q         trunking      146
Fa0/23      desirable        802.1q         trunking      1
Fa0/24      desirable        802.1q         trunking      1

Port        Vlans allowed on trunk
Fa0/19      1-4094
Fa0/20      1-4094
Fa0/21      1-4094
Fa0/22      1-4094
Fa0/23      1-4094
Fa0/24      1-4094

Port        Vlans allowed and active in management domain
Fa0/19      1
Fa0/20      1
Fa0/21      1
Fa0/22      1
Fa0/23      1
Fa0/24      1

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/19      1
Fa0/20      1
Fa0/21      1
Fa0/22      1
Fa0/23      none
Fa0/24      none
SW1#show ip int bri | inc 23|24
FastEthernet0/23       unassigned      YES unset  up                    up
FastEthernet0/24       unassigned      YES unset  up                    up
SW1#show sp
SW1#show spanning-tree vlan 1

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    32769
             Address     001b.d5df.f480
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     001b.d5df.f480
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.3    P2p
Fa0/19              Desg FWD 19        128.21   P2p
Fa0/20              Desg FWD 19        128.22   P2p
Fa0/21              Desg FWD 19        128.23   P2p
Fa0/22              Desg FWD 19        128.24   P2p
Fa0/23              Desg FWD 19        128.25   P2p
Fa0/24              Desg FWD 19        128.26   P2p


SW1#show spanning-tree vlan 1 int fa0
%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (1), with SW2 FastEthernet0/23 (146).
%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (1), with SW2 FastEthernet0/24 (146).
SW1#show spanning-tree vlan 1 int fa0/23

Vlan                Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0001            Desg FWD 19        128.25   P2p
SW1#show spanning-tree inconsistentports

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------

Number of inconsistent ports (segments) in the system : 0

Later, the ports on SW1 start to flap.

%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (1), with SW2 FastEthernet0/23 (146).
%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (1), with SW2 FastEthernet0/24 (146).
%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (1), with SW2 FastEthernet0/23 (146).
%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (1), with SW2 FastEthernet0/24 (146).
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/22, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/21, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/19, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/20, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/22, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/21, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/19, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/20, changed state to up

SW1#show int trunk

Port        Mode             Encapsulation  Status        Native vlan
Fa0/19      desirable        802.1q         trunking      146
Fa0/20      desirable        802.1q         trunking      146
Fa0/21      desirable        802.1q         trunking      146
Fa0/22      desirable        802.1q         trunking      146

Port        Vlans allowed on trunk
Fa0/19      1-4094
Fa0/20      1-4094
Fa0/21      1-4094
Fa0/22      1-4094

Port        Vlans allowed and active in management domain
Fa0/19      1
Fa0/20      1
Fa0/21      1
Fa0/22      1

Port        Vlans in spanning tree forwarding state and not pruned
Fa0/19      1
Fa0/20      1
Fa0/21      1
Fa0/22      1

I appreciate any insight you can offer.

 

 

 

Comments

  • I did this task on an INE CCIE RSv5 Rack with the following results:

    SW1:

    SW1#

    *Mar  1 00:13:30.977: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/19 (146), with SW3 FastEthernet0/19 (1).

    *Mar  1 00:13:30.993: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/20 (146), with SW3 FastEthernet0/20 (1).

    *Mar  1 00:13:31.010: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/21 (146), with SW4 FastEthernet0/21 (1).

    *Mar  1 00:13:31.044: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/22 (146), with SW4 FastEthernet0/22 (1).

    *Mar  1 00:13:31.069: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (146), with SW2 FastEthernet0/23 (1).

    *Mar  1 00:13:31.086: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (146), with SW2 FastEthernet0/24 (1).

    SW1#

    *Mar  1 00:14:30.972: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/19 (146), with SW3 FastEthernet0/19 (1).

    *Mar  1 00:14:30.997: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/20 (146), with SW3 FastEthernet0/20 (1).

    *Mar  1 00:14:31.014: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/21 (146), with SW4 FastEthernet0/21 (1).

    *Mar  1 00:14:31.047: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/22 (146), with SW4 FastEthernet0/22 (1).

    *Mar  1 00:14:31.073: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (146), with SW2 FastEthernet0/23 (1).

    *Mar  1 00:14:31.089: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (146), with SW2 FastEthernet0/24 (1).

    SW1#

    *Mar  1 00:15:30.976: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/19 (146), with SW3 FastEthernet0/19 (1).

    *Mar  1 00:15:31.001: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/20 (146), with SW3 FastEthernet0/20 (1).

    *Mar  1 00:15:31.018: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/21 (146), with SW4 FastEthernet0/21 (1).

    *Mar  1 00:15:31.051: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/22 (146), with SW4 FastEthernet0/22 (1).

    *Mar  1 00:15:31.076: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (146), with SW2 FastEthernet0/23 (1).

    *Mar  1 00:15:31.093: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (146), with SW2 FastEthernet0/24 (1).

    SW1#

    *Mar  1 00:16:30.979: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/19 (146), with SW3 FastEthernet0/19 (1).

    *Mar  1 00:16:31.004: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/20 (146), with SW3 FastEthernet0/20 (1).

    *Mar  1 00:16:31.021: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/21 (146), with SW4 FastEthernet0/21 (1).

    *Mar  1 00:16:31.055: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/22 (146), with SW4 FastEthernet0/22 (1).

    *Mar  1 00:16:31.072: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (146), with SW2 FastEthernet0/23 (1).

    *Mar  1 00:16:31.097: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (146), with SW2 FastEthernet0/24 (1).

    SW1#

    *Mar  1 00:17:04.349: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/23 on VLAN0001. Port consistency restored.

    *Mar  1 00:17:04.349: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/23 on VLAN0146. Port consistency restored.

    *Mar  1 00:17:04.358: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/24 on VLAN0001. Port consistency restored.

    *Mar  1 00:17:04.358: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/24 on VLAN0146. Port consistency restored.

    SW1#

    *Mar  1 00:17:30.983: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/19 (146), with SW3 FastEthernet0/19 (1).

    *Mar  1 00:17:31.008: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/20 (146), with SW3 FastEthernet0/20 (1).

    *Mar  1 00:17:31.025: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/21 (146), with SW4 FastEthernet0/21 (1).

    *Mar  1 00:17:31.050: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/22 (146), with SW4 FastEthernet0/22 (1).

    SW1#

    *Mar  1 00:18:09.764: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/19 on VLAN0001. Port consistency restored.

    *Mar  1 00:18:09.764: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/19 on VLAN0146. Port consistency restored.

    *Mar  1 00:18:09.764: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/20 on VLAN0001. Port consistency restored.

    *Mar  1 00:18:09.764: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/20 on VLAN0146. Port consistency restored.

    SW1#

    *Mar  1 00:18:31.029: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/21 (146), with SW4 FastEthernet0/21 (1).

    *Mar  1 00:18:31.062: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/22 (146), with SW4 FastEthernet0/22 (1).

    SW1#

    *Mar  1 00:19:19.926: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/21 on VLAN0001. Port consistency restored.

    *Mar  1 00:19:19.926: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/21 on VLAN0146. Port consistency restored.

    *Mar  1 00:19:19.926: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/22 on VLAN0001. Port consistency restored.

    *Mar  1 00:19:19.926: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/22 on VLAN0146. Port consistency restored.

    SW1#sh int turnk

                 ^

    % Invalid input detected at '^' marker.

     

    SW1#sh inte trunk

     

    Port        Mode             Encapsulation  Status        Native vlan

    Fa0/19      desirable        802.1q         trunking      146

    Fa0/20      desirable        802.1q         trunking      146

    Fa0/21      desirable        802.1q         trunking      146

    Fa0/22      desirable        802.1q         trunking      146

    Fa0/23      desirable        802.1q         trunking      146

    Fa0/24      desirable        802.1q         trunking      146

     

    Port        Vlans allowed on trunk

    Fa0/19      1-4094

    Fa0/20      1-4094

    Fa0/21      1-4094

    Fa0/22      1-4094

    Fa0/23      1-4094

    Fa0/24      1-4094

     

    Port        Vlans allowed and active in management domain

    Fa0/19      1,146

    Fa0/20      1,146

    Fa0/21      1,146

    Fa0/22      1,146

    Fa0/23      1,146

    Fa0/24      1,146

     

    Port        Vlans in spanning tree forwarding state and not pruned

    Fa0/19      1,146

    Fa0/20      1,146

    Fa0/21      none

    Fa0/22      none

    Fa0/23      1,146

    Fa0/24      1,146

    SW1#

    !!


    SW2:



    SW2(config-if-range)#switchport trunk encap dot1q

    SW2(config-if-range)#switchpo mode auto

                                        ^

    % Invalid input detected at '^' marker.


    SW2(config-if-range)#

    *Mar  1 00:15:31.856: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (1), with SW1 FastEthernet0/23 (146).

    *Mar  1 00:15:31.890: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (1), with SW1 FastEthernet0/24 (146).

    SW2(config-if-range)#switch trunk mode auto

                                      ^

    % Invalid input detected at '^' marker.


    SW2(config-if-range)#switchtrunk dyn auto

                               ^

    % Invalid input detected at '^' marker.


    SW2(config-if-range)#switch trunk dyn auto

                                      ^

    % Invalid input detected at '^' marker.


    SW2(config-if-range)#switch mode dyn

    *Mar  1 00:16:31.860: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/23 (1), with SW1 FastEthernet0/23 (146).

    *Mar  1 00:16:31.894: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/24 (1), with SW1 FastEthernet0/24 (146).

    SW2(config-if-range)#switch mode dyn auto

    SW2(config-if-range)#switchport trunk native vlan 146

    SW2(config-if-range)#end

    SW2#

    *Mar  1 00:16:51.934: %SYS-5-CONFIG_I: Configured from console by console

    SW2#

    *Mar  1 00:17:04.148: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/23 on VLAN0146. Port consistency restored.

    *Mar  1 00:17:04.148: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/23 on VLAN0001. Port consistency restored.

    *Mar  1 00:17:04.156: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/24 on VLAN0146. Port consistency restored.

    *Mar  1 00:17:04.156: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/24 on VLAN0001. Port consistency restored.

    SW2#sh inter trunk


    Port        Mode             Encapsulation  Status        Native vlan

    Fa0/23      auto             802.1q         trunking      146

    Fa0/24      auto             802.1q         trunking      146


    Port        Vlans allowed on trunk

    Fa0/23      1-4094

    Fa0/24      1-4094


    Port        Vlans allowed and active in management domain

    Fa0/23      1,146

    Fa0/24      1,146


    Port        Vlans in spanning tree forwarding state and not pruned

    Fa0/23      1,146

    Fa0/24      none

    SW2#




    SW3:



    SW3>en

    SW3#conf

    Configuring from terminal, memory, or network [terminal]? t

    Enter configuration commands, one per line.  End with CNTL/Z.

    SW3(config)#vlan 146

    SW3(config-vlan)#inter ran f 0/19 - 20

    SW3(config-if-range)#

    *Mar  1 00:17:49.622: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/19 (1), with SW1 FastEthernet0/19 (146).

    *Mar  1 00:17:49.622: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/20 (1), with SW1 FastEthernet0/20 (146).

    SW3(config-if-range)#swit

    *Mar  1 00:17:52.030: %SPANTREE-2-BLOCK_PVID_PEER: Blocking FastEthernet0/19 on VLAN0146. Inconsistent peer vlan.

    *Mar  1 00:17:52.030: %SPANTREE-2-BLOCK_PVID_PEER: Blocking FastEthernet0/20 on VLAN0146. Inconsistent peer vlan.

    SW3(config-if-range)#switchport mode dyn auto

    SW3(config-if-range)#switch trunk nat vlan 146

    SW3(config-if-range)#end

    SW3#

    *Mar  1 00:18:16.164: %SYS-5-CONFIG_I: Configured from console by console

    SW3#

    *Mar  1 00:18:27.086: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/19 on VLAN0146. Port consistency restored.

    *Mar  1 00:18:27.086: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/19 on VLAN0001. Port consistency restored.

    *Mar  1 00:18:27.086: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/20 on VLAN0146. Port consistency restored.

    *Mar  1 00:18:27.086: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/20 on VLAN0001. Port consistency restored.

    SW3#sh inter turnk

                   ^

    % Invalid input detected at '^' marker.


    SW3#sh inter trunk


    Port        Mode             Encapsulation  Status        Native vlan

    Fa0/19      auto             n-802.1q       trunking      146

    Fa0/20      auto             n-802.1q       trunking      146


    Port        Vlans allowed on trunk

    Fa0/19      1-4094

    Fa0/20      1-4094


    Port        Vlans allowed and active in management domain

    Fa0/19      1,146

    Fa0/20      1,146


    Port        Vlans in spanning tree forwarding state and not pruned

    Fa0/19      1,146

    Fa0/20      none

    SW3#




    SW4:



    SW4>en

    SW4#conf t

    Enter configuration commands, one per line.  End with CNTL/Z.

    SW4(config)#vlan 146

    SW4(config-vlan)#

    *Mar  1 00:18:49.375: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/21 (1), with SW1 FastEthernet0/21 (146).

    *Mar  1 00:18:49.425: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/22 (1), with SW1 FastEthernet0/22 (146).

    SW4(config-vlan)#inter ran f 0/21 - 22

    SW4(config-if-range)#s

    *Mar  1 00:19:05.959: %SPANTREE-2-BLOCK_PVID_PEER: Blocking FastEthernet0/21 on VLAN0146. Inconsistent peer vlan.

    *Mar  1 00:19:05.959: %SPANTREE-2-BLOCK_PVID_PEER: Blocking FastEthernet0/22 on VLAN0146. Inconsistent peer vlan.

    SW4(config-if-range)#switch mode dyn auto

    SW4(config-if-range)#switch trunk native vlan 146

    SW4(config-if-range)#end

    SW4#

    *Mar  1 00:19:26.662: %SYS-5-CONFIG_I: Configured from console by console

    SW4#

    *Mar  1 00:19:39.010: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/21 on VLAN0146. Port consistency restored.

    *Mar  1 00:19:39.010: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/21 on VLAN0001. Port consistency restored.

    *Mar  1 00:19:39.010: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/22 on VLAN0146. Port consistency restored.

    *Mar  1 00:19:39.010: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/22 on VLAN0001. Port consistency restored.

    SW4#sh inter tru


    Port        Mode             Encapsulation  Status        Native vlan

    Fa0/21      auto             n-802.1q       trunking      146

    Fa0/22      auto             n-802.1q       trunking      146


    Port        Vlans allowed on trunk

    Fa0/21      1-4094

    Fa0/22      1-4094


    Port        Vlans allowed and active in management domain

    Fa0/21      1,146

    Fa0/22      1,146


    Port        Vlans in spanning tree forwarding state and not pruned

    Fa0/21      1,146

    Fa0/22      none

    SW4#



    SW1:



    SW1#sh interfaces f0/23 switch

    Name: Fa0/23

    Switchport: Enabled

    Administrative Mode: dynamic desirable

    Operational Mode: trunk

    Administrative Trunking Encapsulation: dot1q

    Operational Trunking Encapsulation: dot1q

    Negotiation of Trunking: On

    Access Mode VLAN: 1 (default)

    Trunking Native Mode VLAN: 146 (VLAN0146)

    Administrative Native VLAN tagging: enabled



    SW2:



    SW2#sh inter f0/23 switch

    Name: Fa0/23

    Switchport: Enabled

    Administrative Mode: dynamic auto

    Operational Mode: trunk

    Administrative Trunking Encapsulation: dot1q

    Operational Trunking Encapsulation: dot1q

    Negotiation of Trunking: On

    Access Mode VLAN: 1 (default)

    Trunking Native Mode VLAN: 146 (VLAN0146)

    Administrative Native VLAN tagging: enabled



    I believe that once all of the appropriate ISLs were configured with Native VLAN 146, I no longer saw the syslog errors for Native VLAN Mismatch. Note the syslog messages on SW4 regarding RESTORED PORT CONSISTENCY. Hope this helps!


     

  • I had to shut/no shut from Switch 2 and then it blocked the ports.

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