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Dynamic Trunking Protocol DTP .... which goes with which

Discussion in 'General Cisco Certifications' started by DreTL, Nov 9, 2012.

  1. DreTL

    DreTL New Member

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    Trying to find a which combinations of DTP produce turnks or access ports on switch.
    I try to memorize how the combination match up but it just to much is there an easy way to do it


    I tried to compare it to talking over takes listening as in (trunking - listening , access - talking) but it not a easy, can any one help me remember this stuff an easy way like some kind of trick or mnemonic way.

    Access
    Trunk
    Dynamic Auto
    Dynamic Desirable
    Nonegotiate
     
    Last edited: Nov 10, 2012
  2. danielno8

    danielno8 Gigabyte Poster

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    Can't help with a mnemonic.....but just to let you know it is call Dynamic Trunking Protocol.
     
    Certifications: CCENT, CCNA
    WIP: CCNP
  3. DreTL

    DreTL New Member

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    I was typing too fast I fixed it
     
  4. cisco lab rat

    cisco lab rat Megabyte Poster

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    I have never come across a mnemonic for this, just lab it to remember it

    Trunk and access are port states

    Dy Des and Dy Auto are Cisco protocols which are used to negociate a port into either trunk or access states

    noneg turns the DTP process off on the port

    If you can't find a mnemonic.

    Dy Des + Dy Des = TRUNK

    Dy Des + Dy Auto = TRUNK

    Dy Auto + Dy Auto = STATIC ACCESS

    TRUNK (DTP on) + Dy Des = TRUNK

    TRUNK (DTP on) + Dy Auto = TRUNK

    TRUNK (No Auto) + Dy Des = STATIC ACCESS

    TRUNK (No Auto) + Dy Auto= STATIC ACCESS


    Dy Des + SA = SA

    Dy Des + SA = SA

    Dy AUTO + SA = SA

    You would never want to put Truck againest a static access port
     
    Certifications: Yes I pretty much am!!
    WIP: Fizzicks Degree
  5. DreTL

    DreTL New Member

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    I think I figured it out ...
    from the way I see it
    Access is also most powerful, ... cause anytime it is set with another DTP port setting it will always be forced to Access port
    Trunk and Dyn Des are the next most powerful DTP port type, cause all settings go to trunk except if matchup with a Access port
    Dyn Auto is always listening and will do what ever the apposing DTP port setting is set to so when the apposing port setting is it self Dyn Auto - its set to Access port.

    Posts welcome to oppose or agree with the my logic understanding of DTP
     
    Last edited: Nov 12, 2012
  6. cisco lab rat

    cisco lab rat Megabyte Poster

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    An Access port is one into which you would plug an end user device such as a PC or laptop, this port will receive frames which are not marked which any vlan id (Either Dot1q or ISL) therefore since no vlan marker exists in the frame it is placed into the native vlan of the port as defined by the command
    switchport access vlan "VID"

    To make a port a Access port you would have to run the command
    "switchport mode access"
    The above command will turn DTP off on that port and will not be able to negociate. This is the best and safest setting for all user ports


    Trunk ports are interface which carry frames from one switch to another with the Vlan id (Either Dot1q or ISL) in the frame so the receiving switch can identify the vlan which the frame belongs to.


    Yes, Dyn Auto is listening and will reply only when it receives a DTP frame, it a reactive setting as opposed to Dyn Des which is proactive in sending DTP frames.
    Dyn Auto set itself to Trunk if it receives a DTP frame or Static Access if it does not.

    Hope this helps
     
    Certifications: Yes I pretty much am!!
    WIP: Fizzicks Degree

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