QoS - LLQ, Fragment, TS

Hi all,
I am now confused with this situation:
There're 2 sites
connected via a FrameRelay link, let say the port speed is 768kbps, the
CIR is 384kbps. We need to give voice traffic 50% of the bandwidth with
priority, voice control 5% of the bandwidth. Besides, there's a need to
use fragmentation and traffic shaping.
With this situatio, I have 2 options:
#1 - Configure a policy-map (LLQ)

- configure a map-class to provide FRTS and assign the above policy map
to this map-class, in this map class, I also configure fragment with
the suitable packet size
- assign the map-class to the int DLCI

#2 - configure a policy-map (just like in #1, LLQ)
- configure a map-class to provide FRTS
- create a virtual-template, configure fragmentation and apply policy-map to this interface
- apply virtual-template and map-class to the int DLCI.

In the 2nd solution, I'm wondering where I should apply the policy-map: under virtual-template or under map-class!

And,
one more question: in some books I've read ([productbanned],
internetworkexpert), they say that the cir configured in the map-class
should be 95% of the given CIR (that means, with the question as I
mentioned above, the command in the map-class should be: frame-relay cir 364800).
I know that in the Cisco QoS SRND, Cisco tells us to do so, but I think
that is the situation in reality, not in such an exam unsure.gif ! (I asked Mr.Lapukhov ten days before but got no answer yet)

Anyone having any ideas???

Comments













  • As for where to apply the policy…  Where does the IP traffic
    actually flow?  If you're doing PPPoFR, then the traffic flows through the virtual-access
    interface.  At the DLCI/frame interface, you'll only see PPP traffic.

     

    I think what you are meaning to add is the MINCIR is equal to
    the CIR (384000) because otherwise MQC will assume 1/2 of CIR is available in
    case of BECN and therefore limit guaranteed bandwidth down to 192000bps.

     

    HTH,

     

     



    Scott Morris, 
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    CCSI/JNCI-M/JNCI-ER

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    From: [email protected]
    [mailto:[email protected]] On Behalf Of atoxet

    Sent: Tuesday, January 13, 2009 9:14 PM

    To: [email protected]

    Subject: [CCIE Voice] QoS - LLQ, Fragment, TS

     

    Hi all,

    I am now confused with this situation:

    There're 2 sites connected via a FrameRelay link, let say the port speed is
    768kbps, the CIR is 384kbps. We need to give voice traffic 50% of the bandwidth
    with priority, voice control 5% of the bandwidth. Besides, there's a need to
    use fragmentation and traffic shaping.

    With this situatio, I have 2 options:

    #1 - Configure a policy-map (LLQ)

    - configure a map-class to provide FRTS and assign the above policy map to this
    map-class, in this map class, I also configure fragment with the suitable
    packet size

    - assign the map-class to the int DLCI



    #2 - configure a policy-map (just like in #1, LLQ)

    - configure a map-class to provide FRTS

    - create a virtual-template, configure fragmentation and apply policy-map to
    this interface

    - apply virtual-template and map-class to the int DLCI.



    In the 2nd solution, I'm wondering where I should apply the policy-map: under
    virtual-template or under map-class!



    And, one more question: in some books I've read ([productbanned], internetworkexpert),
    they say that the cir configured in the map-class should be 95% of the given
    CIR (that means, with the question as I mentioned above, the command in the
    map-class should be: frame-relay cir 364800). I know that in the
    Cisco QoS SRND, Cisco tells us to do so, but I think that is the situation in
    reality, not in such an exam unsure.gif! (I asked Mr.



    Anyone having any ideas???







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  • Thanks for your reply,

    So, if PPPoFR is in use, the policy-map will be put under the virtual-template?

    About the number 384000 or 364800: the voice workbook (volume 1) says that we should configure just 95% of the given number in the map-class command, but I don't think that idea is right!

    (if follow the book's instruction, the commands should be:

      map-class FRTS

        frame-relay cir 364800

       frame-relay mincir 364800

    but if follow strictly the Cisco configuration guide, the commands should be:

       map-class FRTS

        frame-relay cir 384000

        frame-relay mincir 384000                )

  • Does anyone give me a guide on this?

  • This is a complex question. 

    1) Determine the fragmentation scheme needed for you tasks. This could be either FRF.12 or MLPPPoFR. If the tasks mentions nothing about running PPP or interoperation with ATM, use FRF.12 (either legacy or MQC-based). In any case, determine the fragment size based on the lowest physical link speed.

    2) If you are using MLPPP there are just TWO correct way of setting the things up: using a virtual template of multilink interface. In any case, you apply the LLQ policy under the new virtual interface AND use legacy FRTS at the Frame-Relay physical interface.

    3) As for the 95% rule. Only resort to it if the task explicitly asks you to account you for extra L1/L2 overhead (bit stuffing, additional headers) or tells you to pick up the actual CIR values based on the SRND recommendations. In other case, use the exact CIR values. It never hurts to consult the proctor in this situation.

    4) Updated VOL1 contains breakdowns for QoS sections, specifically for FRF.12/MLPPP fragmentation.

     

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