From: Todd, Douglas M. (DTODD@PARTNERS.ORG)
Date: Mon Feb 12 2007 - 01:43:37 ART
All:
I am working on a spread sheet to figure this out.
But this is how I believe it works from reading all the other posts. Let me
give this a try (correct me where I am off):
If you do not specify a Bc value, then you can the find Tc value.
In this thread, CIR is 320k and Bc is 8k
So:
Tc = Bc/CIR
Tc = 8000/320000
.025 is your Tc value.
If you do not specify the Bc value then the system must use the defaults:
With Bc = 0
CIR/AR is less than and NOT equal to 640k then your tc will be .125
CIR/AR is between 640k-768k and NOT equal to 640k and 768 then your Tc will be
1/2 the previous (rounded up) or .063ms
CIR/AR is between 768k-1024k and NOT equal to 768k - 1536k then your Tc will be
1/2 the previous threshold or .032ms
CIR/AR > 1536 you are in the .016ms range.
Briefly:
All ms are rounded up.
AR/CIR <!= 640k Tc = .125 (1/8 of 1 Second)
AR/CIR >!= 640k But AR/CIR <!= 768k Tc = .063 (1/16 of a Second)
AR/CIR >!= 768k But AR/CIR <!= 1024k Tc = .032 (1/32 of a second)
AR/CIR >!= 1024k but AR/CIR <!= 1536k Tc = .016 (1/64 of a Second)
If you do specify a Bc value you must solve for Tc, then you can solve for the
Bite Limit and Increment.
Bite Limit = (CIR*Tc)/8
If you are missing any of the values you can solve for any of the others. When I
have the data verified I'll send it out.
DMT
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Gary
Braver
Sent: Sunday, February 11, 2007 5:02 PM
To: mariam.tatevik@yahoo.com; ccielab@groupstudy.com
Subject: RE: to verify Tc
My understanding of CB shaping defaults
Rate <= 320 kbps
Bc 8000 bits
Be = Bc = 8000
Tc = Bc/shaping rate
Rate > 320 kbps
Bc = shaping rate * Tc
Be = Bc
TC = 25 ms
I too thought FRTS defaulted to Tc=125ms
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
mariam.tatevik@yahoo.com
Sent: Saturday, February 10, 2007 10:20 AM
To: ccielab@groupstudy.com
Subject: to verify Tc
Hello GS
just want to verify all default Tc values:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! police Tc = 250ms => bc = cir/32
! shape Tc = 25ms for CIR > 320kbps
! shape Tc = Bc/CIR for CIR <= 320Kbps
! priority [burst] Tc = 200ms
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! FRTS Tc = 125ms
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Is the above list correct ?
THX
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