Some questions about trunking

Discussion in 'Cisco' started by Mark, Aug 30, 2008.

  1. Mark

    Mark Guest

    I'm studyng for CCNA exam, and I am a little confused about encapsulation
    dot1Q command.
    When do I need to use that command?
    Does it required for configuring every trunk port on switch or what?

    Thanks!
    Mark, Aug 30, 2008
    #1
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  2. Mark

    Trendkill Guest

    On Aug 30, 7:19 am, "Mark" <> wrote:
    > I'm studyng for CCNA exam, and I am a little confused about encapsulation
    > dot1Q command.
    > When do I need to use that command?
    > Does it required for configuring every trunk port on switch or what?
    >
    > Thanks!


    All trunks must use either dot1q or isl encapsulation. You use that
    command, or the equivalent ISL command to set the encapsulation type,
    and yes it must be on each port that you are trunking on the switch.
    Additionally, the switch on the other side of the trunk must be
    configured the same way.
    Trendkill, Aug 30, 2008
    #2
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  3. Mark

    Mark Guest

    "headsetadapter.com" <> wrote in message
    news:p...
    > Mark,
    >
    > It depends on the switch model. Some switches by default have ports
    > (interfaces) in the "access mode" and will never become trunks. Some
    > switches (especially with newer software) have all ports in "auto mode",
    > so, if they sense the active attempt to become trunk - they will become a
    > trunk. Some switches support two encapsulation methods - ISL and 802.1q,
    > so, you have to specify which trunking protocol to use (older switches
    > have ISL by default). Newer switches do not support the Cisco's
    > proprietary ISL protocol, so, the only option for them is DOT1Q, so, you
    > do not have to specify it.
    >


    Thanks for answers, now it is clear. The types of switch are 3550/3560 and
    2950T.
    Thanks again!
    Mark, Aug 30, 2008
    #3
  4. Mark

    Bob Vaughan Guest

    In article <g9c14b$l3v$-com.hr>, Mark <> wrote:
    >
    >"headsetadapter.com" <> wrote in message
    >news:p...
    >> Mark,
    >>
    >> It depends on the switch model. Some switches by default have ports
    >> (interfaces) in the "access mode" and will never become trunks. Some
    >> switches (especially with newer software) have all ports in "auto mode",
    >> so, if they sense the active attempt to become trunk - they will become a
    >> trunk. Some switches support two encapsulation methods - ISL and 802.1q,
    >> so, you have to specify which trunking protocol to use (older switches
    >> have ISL by default). Newer switches do not support the Cisco's
    >> proprietary ISL protocol, so, the only option for them is DOT1Q, so, you
    >> do not have to specify it.
    >>

    >
    >Thanks for answers, now it is clear. The types of switch are 3550/3560 and
    >2950T.
    >Thanks again!
    >


    The 2950 is dot1q only, the 3550 supports isl and dot1q. I don't know
    about the 3560.

    >



    --
    -- Welcome My Son, Welcome To The Machine --
    Bob Vaughan | techie @ tantivy.net |
    | P.O. Box 19792, Stanford, Ca 94309 |
    -- I am Me, I am only Me, And no one else is Me, What could be simpler? --
    Bob Vaughan, Sep 1, 2008
    #4
  5. (Bob Vaughan) writes:
    >In article <g9c14b$l3v$-com.hr>, Mark <> wrote:
    >>
    >>"headsetadapter.com" <> wrote in message
    >>news:p...
    >>> Mark,
    >>>
    >>> It depends on the switch model. Some switches by default have ports
    >>> (interfaces) in the "access mode" and will never become trunks. Some
    >>> switches (especially with newer software) have all ports in "auto mode",
    >>> so, if they sense the active attempt to become trunk - they will become a
    >>> trunk. Some switches support two encapsulation methods - ISL and 802.1q,
    >>> so, you have to specify which trunking protocol to use (older switches
    >>> have ISL by default). Newer switches do not support the Cisco's
    >>> proprietary ISL protocol, so, the only option for them is DOT1Q, so, you
    >>> do not have to specify it.
    >>>

    >>
    >>Thanks for answers, now it is clear. The types of switch are 3550/3560 and
    >>2950T.
    >>Thanks again!
    >>


    >The 2950 is dot1q only, the 3550 supports isl and dot1q. I don't know
    >about the 3560.



    The 3560 can do ISL and .1q trunking both. The 2950/2960 are .1q only
    as you state.
    Doug McIntyre, Sep 1, 2008
    #5
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