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Forums » Internetwork Expert Products » CCIE R&S Lab Workbook Volume II Version 4.1 » IEWB-RS Volume 2 Version 4.1 Lab 12 » Task 8.1 FRTS
Latest post 12-17-2008 1:40 PM by TKDJ. 6 replies.
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  • 09-29-2008 8:48 PM

    • ndiayemalick
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    Task 8.1 FRTS

    Reply Contact

    Hello experts,

     

    how did they come up with a byte limit of 640 for Voice packets?

     

    Best regards
    • Post Points: 20

  • 09-29-2008 9:23 PM In reply to

    Re: Task 8.1 FRTS

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    http://forum.internetworkexpert.com/ubbthreads.php/ubb/showflat/Number/21666/page/3#Post21666

    R2#sh traffic | in Access|VC|204
           Access Target    Byte   Sustain   Excess    Interval  Increment Adapt
    VC     List   Rate      Limit  bits/int  bits/int  (ms)      (bytes)   Active
    204           512000    640    5120      0         10        640       - 

    ..i got the math part on getting to the 10 ms..which produces the above byte limit 640...hey thats a nice little trick..i dont have to divide by 8...i can just look a the traffic byte limit in "show traffic output""  

    ..but didnt set up the fragmentation...arghh INTERLEAVE!!!  :-(  :-(

    Bc = CIR X Tc/1000  Bc = 5120       5120/8 = 640       1 byte = 8 bits
    • Post Points: 20

  • 09-29-2008 10:31 PM In reply to

    • ndiayemalick
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    Re: Task 8.1 FRTS

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    So Daniel if I get it right, you divide the BC by 8 in order to get the Byte limit?
    • Post Points: 20

  • 09-30-2008 3:36 AM In reply to

    Re: Task 8.1 FRTS

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    ...ndiayemalick, do you ever sleep? 

    ....answer yes...

    .and check out the archive from lab 19...this guy (storm) gives a break down on a similar issue...towards the end of his comments he also mentions to divide by eight to convert bytes to bits....  

    http://forum.internetworkexpert.com/ubbthreads.php/ubb/showflat/Number/15069/page/3#Post15069
    • Post Points: 20

  • 09-30-2008 4:50 AM In reply to

    • ndiayemalick
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    Re: Task 8.1 FRTS

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    Cool I wish I could sleep bro but ever since I started this CCIE stuff, I have been addicted like someone on crack. This is very good explaination.

    Thanks

     

    How far are you in your preparations?
    • Post Points: 20

  • 09-30-2008 5:39 AM In reply to

    Re: Task 8.1 FRTS

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    ..sending u email
    • Post Points: 20

  • 12-17-2008 1:40 PM In reply to

    • TKDJ
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    • Joined on 11-15-2008
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    Re: Task 8.1 FRTS

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    I'm confused (although it's happening loads recently!)...

    I was under the impression that fragment size was calculated using physical line rate, due to the fact that its at this rate that bits a "pushed" out, thus

    (1536000* 0.01)/8 = 1920 <--- Beyond fragment limit allows by IOS.

    The Sol guide and other postings all use CIR with the obvious answer of 640.

    What am I missing?

    Cheers all!

     

    Extract from:

    Legacy Frame-Relay Traffic Shaping

    By Petr Lapukhov, CCIE #16379

    - Fragment size is calculated based on physical interface speed to allow minimum serialization delay

     

     

     

     
    • Post Points: 5
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