Native Vlan Mismatch error

Discussion in 'Cisco' started by Someone, Jan 20, 2008.

  1. Someone

    Someone Guest

    I got two errors showing up on console:

    (1) 4w5d: %LINK-4-ERROR: FastEthernet0/3 is experiencing errors


    (2) 4w5d: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered
    on FastEthernet0/16 (20), with Switch3 FastEthernet0/48 (1).
    Also, one port on one of the switch is flapping.

    There are there switches on this rack connected by both fiber and
    crossover cable. How can I fix these problems. Thanks.
     
    Someone, Jan 20, 2008
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  2. Someone

    Greeley

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    Post the config for both those ports. Odds are its a line or two that are incorrect on the config.

    -G
     
    Greeley, Jan 20, 2008
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  3. Someone

    sksri83

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    problem

    Hi,

    Check for duplex mismatches between both ends of the link.

    if problem not solve please confirm me config .

    saurabh


     
    sksri83, Jan 21, 2008
    #3
  4. Someone

    Trendkill Guest

    Change the native vlan on both switches to match. If its IOS based, I
    would think you need to do a switchport mode access, switchport access
    vlan <nativevlan>. Then put your trunk statements back. On the
    catalyst side, set vlan <port> <nativevlan>, and then you again may
    need you put your trunking statements back. Its probably not a major
    issue, but you want your trunks in the same native vlan before
    configuring trunking.
     
    Trendkill, Jan 21, 2008
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  5. Someone

    notaccie Guest

    if you are just passing traffic across a common vlan,no trunking, set
    each port to the same vlan and access mode.

    If you are using 802.1q, though, you might want to define a native
    vlan for each dot1q trunk. The native vlan won't be tagged, and allow
    only the desired vlans to pass through. Don't use the native vlan
    number anywhere else in your net.

    if 888 is the native vlan and you want to pass 5,6,7 then something
    like this works. add other i/f commands as suits your env.

    IOS:

    interface command:

    switchport
    switchport trunk encapsulation dot1q
    switchport trunk native vlan 888
    switchport trunk allowed vlan 5-7
    switchport mode trunk
    etc.

    catos:

    set vlan 888 mod/port

    set trunk mod/port <desireable, on, ...> dot1q 5-7


    works well. the next dot1q tunnel you define might use 889 for the
    native vlan, etc. keep track, as always, of where vlans occur. keep
    as local as possible.
     
    notaccie, Jan 21, 2008
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