Quick QinQ question

Discussion in 'Cisco' started by thcollicutt, Aug 24, 2007.

  1. thcollicutt

    thcollicutt Guest

    I have a quick question. Someone gave me some info, and I want to
    verify it.

    QinQ needs to have a switch capable of accepting double tagging ports
    to be an edge device. I've been told that if you have a network made
    on switches, only the the ones at the provider edge need to understand
    double tagging. The ones inside the network only see the outer tag,
    and do not have to be configured for double tagging.

    Is this true, or is this guy full of it?
     
    thcollicutt, Aug 24, 2007
    #1
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  2. thcollicutt

    John Guest

    On Aug 24, 4:23 pm, thcollicutt <> wrote:
    > I have a quick question. Someone gave me some info, and I want to
    > verify it.
    >
    > QinQ needs to have a switch capable of accepting double tagging ports
    > to be an edge device. I've been told that if you have a network made
    > on switches, only the the ones at the provider edge need to understand
    > double tagging. The ones inside the network only see the outer tag,
    > and do not have to be configured for double tagging.
    >
    > Is this true, or is this guy full of it?


    >From what I've read so far, this statement is not true. However I have

    no experience so far about this. I suspect that if the switches don't
    know the q-in-q format, they cannot read correctly the frame and learn
    the associated source/destination mac addresses.

    the intermediate switches must have the ability to pass q-in-q frames
    and also if you need to pass full frames (eg. 1500 bytes) they must
    support the extra bytes of the q-in-q header.

    however, you may use lower end switches to pass this traffic, which
    may not be capable to act as a demarcation device. eg. on 4500 series
    the supII+ may pass QinQ but cannot be used as a QinQ entry point.
    (add the extra header).

    --John
     
    John, Aug 24, 2007
    #2
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