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timaz
 Post subject: traffic shaping
PostPosted: Sat Apr 21, 2012 7:58 am 
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Hi all; I'm confused !

with this command, what are the values of Bc and Be?

interface fast 0/0
traffic-shape group 101 500000

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Perlhack
 Post subject: Re: traffic shaping
PostPosted: Sat Apr 21, 2012 8:35 am 
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Value of Bc can be found by knowing the Tc, but not Be ... thats extra.

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timaz
 Post subject: Re: traffic shaping
PostPosted: Sat Apr 21, 2012 8:49 am 
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Perlhack wrote:
Value of Bc can be found by knowing the Tc, but not Be ... thats extra.



so what are the values of Bc and Bc with just the mentioned command?!!

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mellowd
 Post subject: Re: traffic shaping
PostPosted: Sat Apr 21, 2012 9:06 am 
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Why not do a show traffic-shape and see for yourself?

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timaz
 Post subject: Re: traffic shaping
PostPosted: Sat Apr 21, 2012 9:45 am 
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mellowd wrote:
Why not do a show traffic-shape and see for yourself?


I take this command from "CCIE RS cert guide". actually this command has output that shows the Bc and Be values. but I cannot calculate the same values. in this book, the author said "if we don't determine the Bc and Be values, it will be 0ne-quarter of the shaping rate". but with regards to this formula, {Tc=Bc/shapingRate}, the values must be different than what is shawn in the output. so if you see this command, can you calculate Bc and Be? .. what is those values?

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timaz
 Post subject: Re: traffic shaping
PostPosted: Sat Apr 21, 2012 10:31 am 
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I think the famous formula {Tc=Bc/shapingRate} don't apply on GTS. am I right?

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Perlhack
 Post subject: Re: traffic shaping
PostPosted: Sat Apr 21, 2012 2:39 pm 
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IOS will apply a default Tc value for the shaper. I do not recall what the default value really is but if its 25ms for a 50M shaper:

Tc = 25 ms | Tc in a sec = 40 | Bc = 1250000 bits

Max Be value can not be determined without knowing the line rate of the circuit.

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timaz
 Post subject: Re: traffic shaping
PostPosted: Sat Apr 21, 2012 2:56 pm 
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the output being shown in this book has these values:

Bc=12000 bits
Be=12000 bits
Tc=24 ms

these values are true with the formula, but I don't know how these are calculated? does anyone know?

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timaz
 Post subject: Re: traffic shaping
PostPosted: Sun Apr 22, 2012 7:47 am 
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nobody knows?

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d_estin_y
 Post subject: Re: traffic shaping
PostPosted: Tue Apr 24, 2012 4:05 am 
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timaz wrote:
the output being shown in this book has these values:

Bc=12000 bits
Be=12000 bits
Tc=24 ms

these values are true with the formula, but I don't know how these are calculated? does anyone know?

I do not get how the Tc is calculated.

but with the given Tc of 24ms, the calculation of Bc is

500000 * 24 / 1000

which means you could send 12000 bits each 24ms
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timaz
 Post subject: Re: traffic shaping
PostPosted: Tue Apr 24, 2012 5:54 am 
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d_estin_y wrote:
timaz wrote:
the output being shown in this book has these values:

Bc=12000 bits
Be=12000 bits
Tc=24 ms

these values are true with the formula, but I don't know how these are calculated? does anyone know?

I do not get how the Tc is calculated.

but with the given Tc of 24ms, the calculation of Bc is

500000 * 24 / 1000

which means you could send 12000 bits each 24ms



yes, that's true. the calculated values are true with this formula. but I don't understand how they are calculated with regards to the command. i think there must be default values. but what they are?

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Perlhack
 Post subject: Re: traffic shaping
PostPosted: Tue Apr 24, 2012 7:45 am 
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Code:
C1811#show traffic-shape

Interface   Vl1
       Access Target    Byte   Sustain   Excess    Interval  Increment Adapt
VC     List   Rate      Limit  bits/int  bits/int  (ms)      (bytes)   Active
-             100000000 625000 2500000   2500000   25        312500    -   
C1811#

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