RE: CALCULATE FRAGMENT SIZE IN FRAME RELAY is there a formula??

From: Victor Cappuccio (vcappuccio@ccbootcamp.com)
Date: Sun Sep 02 2007 - 16:53:30 ART

Committed Rate Measurement Interval (Tc)Time interval over which Bc or (Bc+
Be) bits are transmitted. Tc is calculated as Tc = Bc / CIR. The Tc value is
not directly configured on Cisco routers. It is calculated after the Bc and
CIR values are configured. Tc cannot exceed 125 ms

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_configuration_exampl
e09186a0080094af9.shtml

thanks,
Victor Cappuccio.-
- CCSI# 31452

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-----Original Message-----
From: nobody@groupstudy.com on behalf of Joseph Brunner
Sent: Sun 02-Sep-07 12:26 PM
To: Carlos Trujillo Jimenez; ccielab@groupstudy.com
Cc: ctrujillo@magenta.cl
Subject: RE: CALCULATE FRAGMENT SIZE IN FRAME RELAY is there a formula??

The "fomula" for fragment size is just 1/8 (as you need to enter bytes) of
your 10ms tc, which you set by setting bc.

Whether what size fragment is good for what type of voice codec, is a
discussion best for the voice IE lab, and its covered in Wendell Odom's QOS
guide.

-Joe

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Carlos Trujillo Jimenez
Sent: Sunday, September 02, 2007 11:59 AM
To: ccielab@groupstudy.com
Cc: ctrujillo@magenta.cl
Subject: CALCULATE FRAGMENT SIZE IN FRAME RELAY is there a formula??

Dear partners.

Please I want you to confirm if I am correct or not in the answer of the
following task.
Scenario:

Data and voice packets are traversing the frame relay circuit between RA and

RB.
Enable frame relay traffic shaping in a interface according to the provided
CIR (256 K). and ensure all the shaping intervals are the smallest possible,

and that a single packet cannot take more than one interval to be
transmited.

so in each router I enable frame relay traffic shaping, associating the
following map-class

map-class frame-relay SHAPING
frame relay cir 256000
frame relay bc 2560
frame relay fragment 320

For the last one "FRAME RELAY FRAGMENT 320" what is the formula for
calculating it?? I mean I know that when larga packets exced the 320 size,
they get compressed right?, but how do I get the 320 size?? is there a
formula to calculate it??

I noticed also when I do a "show traffic shape" without enabling
fragmentation it shows me the following response:

Interface Se0/0
       Access Target Byte Sustain Excess Interval Increment Adapt
VC List Rate Limit bits/int bits/int (ms) (bytes)
Active
402 256000 320 2560 0 10 320 -
403 256000 320 2560 0 10 320 -
405 256000 320 2560 0 10 320 -
406 256000 320 2560 0 10 320 -
413 256000 320 2560 0 10 320 -
506 256000 320 2560 0 10 320 -
513 256000 320 2560 0 10 320 -
401 256000 320 2560 0 10 320 -

So my question is, for calculating the fragment size, I simply copy the
value of the "byte limit" who shows me the show traffic shape output??

Thanks a lot, and regards.

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