Re: FRTS and Be - first interval?

From: Edison Ortiz (edisonmortiz@gmail.com)
Date: Wed May 23 2007 - 10:45:01 ART


I'm afraid the task is either worded improperly and you are not reading the
question right.
Is this task from a workbook ? Can you copy and paste verbatim what's asked ?

Thanks

__

Edison Ortiz
(Routing & Switching, CCIE # 17943)

  ----- Original Message -----
  From: Andy
  To: Edison Ortiz
  Cc: Group Study (E-mail)
  Sent: Wednesday, May 23, 2007 6:51 AM
  Subject: Re: FRTS and Be - first interval?

  Thanks Edison, still dont get it tho :-(

  AR = 384000
  CIR = 192000
  Bc = 24000
  Be = 24000

  Configure as :
  frame-relay CIR 192000
  frame-relay bc 24000
  frame-relay mincir 128000
  frame-relay be 24000

  Gives us the following:
  Tc1 : (Bc 24000 + Be 24000 )
  Tc2 : (Bc 24000 + Be 24000)
  Tc3 : (Bc 24000 + Be 24000)
  Tc4 : (Bc 24000 + Be 24000)
  Tc5 : (Bc 24000 + Be 24000)
  Tc6 : (Bc 24000 + Be 24000)
  Tc7 : (Bc 24000 + Be 24000)
  Tc8 : (Bc 24000 + Be 24000)

  but, if we can only send Be during first interval (
http://www.cisco.com/warp/customer/125/traffic_shaping_6151.html
   "The amount of excess data allowed to be sent during first Tc interval in
bits "), then this would mean

  Tc1 : (Bc 24000 + Be 24000) = ok
  Tc2 : (Bc 24000 + Be 24000) = only Bc sent as Be sent ONLY during Tc1
  Tc3 : (Bc 24000 + Be 24000) = only Bc sent as Be sent ONLY during Tc1
  Tc4 : (Bc 24000 + Be 24000) = only Bc sent as Be sent ONLY during Tc1
  Tc5 : (Bc 24000 + Be 24000) = only Bc sent as Be sent ONLY during Tc1
  Tc6 : (Bc 24000 + Be 24000) = only Bc sent as Be sent ONLY during Tc1
  Tc7 : (Bc 24000 + Be 24000) = only Bc sent as Be sent ONLY during Tc1
  Tc8 : (Bc 24000 + Be 24000) = only Bc sent as Be sent ONLY during Tc1

  Giving us (Bc 24000 x 8) + (Be 24000 from Tc1) = 216000 AR !

  Therefore should we not configure Be as 192000 to give us
  Tc1 : (Bc 24000 + Be 192000) = ok
  Tc2 : (Bc 24000 + Be 192000) = only Bc sent as Be sent ONLY during Tc1
  Tc3 : (Bc 24000 + Be 192000) = only Bc sent as Be sent ONLY during Tc1
  Tc4 : (Bc 24000 + Be 192000) = only Bc sent as Be sent ONLY during Tc1
  Tc5 : (Bc 24000 + Be 192000) = only Bc sent as Be sent ONLY during Tc1
  Tc6 : (Bc 24000 + Be 192000) = only Bc sent as Be sent ONLY during Tc1
  Tc7 : (Bc 24000 + Be 192000) = only Bc sent as Be sent ONLY during Tc1
  Tc8 : (Bc 24000 + Be 192000) = only Bc sent as Be sent ONLY during Tc1

  Can someone explain (or unexplain :-) the above, I understand all the maths,
just this first time interval Tc1 is getting me.

  -A

  On 22/05/07, Edison Ortiz <edisonmortiz@gmail.com> wrote:
    Andy,

    You are sending 24kilobits per TC which is 125ms or 1/8 of a second.

    The CIR is set to 192 kilobits per *second*.

    Multiply 24 * 8 and you will get what you are sending per second which is
192

    HTH,

    __

    Edison Ortiz
    (Routing & Switching, CCIE # 17943)

      ----- Original Message -----
      From: Andy
      To: Edison Ortiz
      Cc: Group Study (E-mail)
      Sent: Tuesday, May 22, 2007 10:43 AM
      Subject: Re: FRTS and Be - first interval?

      Quote

> Why is Be 24000 and not 192000, if the definition of Be is "The number
of
> non-committed bits the router is allowed to send above Bc during the
first
> interval Tc"

      /Quote

      The bit that confuses me, is that it says it sends during the first
interval Tc. This suggests (given default Tc)

      Tc1 Tc2 Tc3 Tc4 Tc5 Tc6 Tc7 Tc8
      (Bc + Be) (Bc) (Bc) (Bc) (Bc) (Bc) (Bc) (Bc)

      Therefore I would config Be at 192000, so as to reach AR.
      If we configure Be at 24000, and given that Be only sends during first
Tc, we are only getting Bc (192000) + Be for Tc1 (24000) which does not equal
Ar.

      I understand the maths and how to acheive the figures, what I dont get
is why do we configure Be for each Tc "Tc1 - Tc8" when it says Be is only sent
during first Tc (Tc1).
      -A

      *************************************************************

      On 22/05/07, Edison Ortiz <edisonmortiz@gmail.com > wrote:
        Quote
> Why is Be 24000 and not 192000, if the definition of Be is "The
number of
> non-committed bits the router is allowed to send above Bc during the
first
> interval Tc"
        /Quote

        You have to use the same Tc value for the Be that was used for the
Bc.
        As you stated originally, "use the default Tc value" which is 125ms.

        So they gave you the Access Rate, CIR and MinCIR.

        You take the CIR 192000 and multiply it for .125 which gives you the
Bc
        (24000)
        You have another 192kbps for bursting (384000 - 192000) so you take
that
        amount
        and do the same calculation (192000 * .125) to get the Be (24000)

        __

        Edison Ortiz
        (Routing & Switching, CCIE # 17943)

        ----- Original Message -----
        From: "Andy" < and123and@googlemail.com >
        To: "Group Study (E-mail)" <ccielab@groupstudy.com>
        Sent: Tuesday, May 22, 2007 5:42 AM
        Subject: FRTS and Be - first interval?

> http://www.internetworkexpert.com/resources/01700368.htm
> Slide 31 Example 2
>
> The example in above URL shows:
> Router has AR of 384000
> CIR of 192000
> MinCIR 128000
> Use default Tc and allow to burst up to AR.
>
> The configuration shows:
> frame-relay CIR 192000
> frame-relay bc 24000
> frame-relay mincir 128000
> frame-relay be 24000
>
> Why is Be 24000 and not 192000, if the definition of Be is "The
number of
> non-committed bits the router is allowed to send above Bc during the
first
> interval Tc"
>
> Confused :-/
>
>



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