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This topic contains 14 replies, has 8 voices, and was last updated by  Rene Molenaar 1 week, 1 day ago.

Viewing 14 posts - 1 through 14 (of 14 total)
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  • #15319


    You have a very unique way of explaining, Clear and direct to the point. I am very grateful.
    Thank you


    kareem mohamed

    I really appreciate your efforts :)



    Hi ,
    Im following you LAB but i would like to know how to change the Operational Mode
    status .
    Every times i would like to change it , it doesn’t work .

    #sh int Fa0/21 switchport
    Name: Fa0/21
    Switchport: Enabled
    Administrative Mode: trunk
    Operational Mode: down <—
    Administrative Trunking Encapsulation: dot1q
    Negotiation of Trunking: Off
    Access Mode VLAN: 50 (TesteIMO(NOTOUCH))
    Trunking Native Mode VLAN: 1 (default)
    Voice VLAN: none

    Thanks for your help .


    bharathi n

    Can u check whether u made it no shut?



    Please clarify how to interpret the table you listed in the page below with different modes


    Rene Molenaar

    The horizontal values are for “switch 1” and the vertical values for “switch 2”.

    For example, if you use “dynamic auto” on switch 1 and 2 then the result will be access mode.


    Srinivasan C

    Hi Rene,
    Network operators knows which ports are connected to switch and hosts. They can configure access mode or trunk mode accordingly.
    Why do we need Dynamic access and Dynamic auto ? In what scenario we use it in
    production network?



    Rene Molenaar

    Hi SV,

    I can’t think of any good reason to use dynamic auto or desirable. It’s best always to use static access or trunk mode.



    Srinivasan C

    Hi Rene,
    Thanks for your quick reply!




    Rene, question, on your last compare example, its static access and static trunk, the result was trunk on both sides, so its a working trunk port? but on your table that you created, the Static Trunk and Static Access has a “Limited” value. care to explain why its Limited? and what does it do on the switch?


    Rene Molenaar

    Hi John,

    When you mix access and trunk mode, we get to see this message:

    %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non trunk FastEthernet0/14 VLAN1.
    %SPANTREE-7-BLOCK_PORT_TYPE: Blocking FastEthernet0/14 on VLAN0001. Inconsistent port type.
    %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/14 on VLAN0001. Port consistency restored.

    The trunk will send BPDUs for each VLAN, our access mode interface only sends one BPDU so that’s why CDP reports this error. This won’t be a working trunk but I think the access mode VLAN (VLAN1) will work.

    I’d have to give this a try to see if it works.



    Faisal A

    Thanks .

    It’s awesome.


    Donald S


    how do you turn trunk negotiation back on?


    Rene Molenaar

    Hi Donald,

    “switchport nonegotiate” disabled it and “no switchport nonegotiate” enables it again.


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