From: Jim Phillipo (jim.phillipo@guardent.com)
Date: Thu Jul 10 2003 - 21:16:05 GMT-3
Just to confirm
Rate = 128000 so BC = 24000 BE = 48000
-----Original Message-----
From: Brian McGahan [mailto:brian@cyscoexpert.com]
Sent: Thursday, July 10, 2003 6:47 PM
To: 'Jim Phillipo'
Subject: RE: More QOS CAR example
Jim,
What platform/version is this?
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Toll Free: 866.CyscoXP
Fax: 847.674.2625
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Jim Phillipo
> Sent: Thursday, July 10, 2003 5:43 PM
> To: 'Brian McGahan'; 'Jonathan V Hays'; Jim Phillipo;
> ccielab@groupstudy.com
> Subject: RE: More QOS CAR example
>
> Brian,
>
> When I type in Police 80000 I do not get defaults ?
> !
> policy-map jim
> class jim
> police cir 80000
> !
> !
>
> -----Original Message-----
> From: Brian McGahan [mailto:brian@cyscoexpert.com]
> Sent: Thursday, July 10, 2003 5:27 PM
> To: 'Brian McGahan'; 'Jonathan V Hays'; 'Jim Phillipo';
> ccielab@groupstudy.com
> Subject: RE: More QOS CAR example
>
>
> Group,
>
> As a follow up to my previous post, I did some testing to
> illustrate how the burst values of the CAR statement affect the
> configured rate.
>
> The following output is from a router connected to the internet
> which is policing NNTP traffic (usenet news). I am downloading files
> from alt.binaries.sounds.mp3 (for research purposes only of course),
and
> changing the burst values of the police statement to show the effect.
> The goal of our policing is to keep our NNTP traffic at or below
80kpbs.
>
> In the first example, I entered the 'police 80000' statement.
> This results in the default values of:
>
> Police 80000 2500 2500 conform-action transmit exceed-action drop
>
> http://www.cyscoexpert.com/adminimages/car4.gif
>
> As you can see from the output, I am averaging a rate of about
> 30kbps. This is much lower than the expected target rate.
>
> In the next example, the burst values are modified to meet the
> recommended formula. The 'police 80000 15000 30000' statement was
> entered, which resulted in:
>
> Police 80000 15000 30000 conform-action transmit exceed-action drop
>
> http://www.cyscoexpert.com/adminimages/car3.gif
>
> As you can see from this output, the average rate is in the high
> 70kbps range, which is very close to our desired target rate.
>
> The calculation for CAR values should therefore be as follows:
>
> Normal_burst bytes = target_rate bps * ( 1 byte / 8 bits ) * 1.5
seconds
> Excess_burst bytes = normal_burst * 2
>
>
>
> HTH,
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> Toll Free: 866.CyscoXP
> Fax: 847.674.2625
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Brian McGahan
> > Sent: Thursday, July 10, 2003 2:32 PM
> > To: 'Jonathan V Hays'; 'Jim Phillipo'; ccielab@groupstudy.com
> > Subject: RE: More QOS CAR example
> >
> > Jim & Jonathan,
> >
> > Configuring the burst values to correspond to the formula *IS*
> > necessary. Test it with actual traffic and you will see that the
rate
> > does not correctly conform unless you use the recommended burst
> values.
> > I'm not sure where these authors are getting their burst values
from,
> > but they're not correct.
> >
> > HTH
> >
> > Brian McGahan, CCIE #8593
> > Director of Design and Implementation
> > brian@cyscoexpert.com
> >
> > CyscoExpert Corporation
> > Internetwork Consulting & Training
> > Toll Free: 866.CyscoXP
> > Fax: 847.674.2625
> >
> >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf
> > Of
> > > Jonathan V Hays
> > > Sent: Wednesday, July 09, 2003 6:37 PM
> > > To: 'Jim Phillipo'; ccielab@groupstudy.com
> > > Subject: RE: More QOS CAR example
> > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > > > Behalf Of Jim Phillipo
> > > > Sent: Wednesday, July 09, 2003 6:48 PM
> > > > To: ccielab@groupstudy.com
> > > > Subject: More QOS CAR example
> > > >
> > > >
> > > > This is from VEGESNA's book
> > > >
> > > > All traffic except HTTP over a rate of 15 Mbps is marked with
> > > > IP Prec 4
> > > > HTTP over 15 Mbps is marked with 0
> > > > This is a 30 Mbps pipe from provider
> > > >
> > > > There answer:
> > > >
> > > > rate-limit input 30000000 15000 15000 conform-action continue
> > > > exceed-action-drop
> > > > rate-limit input access-group 101 15000000 10000 10000
> > conform-action
> > > > set-prec-transmit 4 exceed-action set-prec-transmit 0
> > > > rate-limit input 30000000 15000 15000 conform-action
> > > > set-prec-transmit 4
> > > > exceed-action set-prec-transmit 4
> > > >
> > > > access-list 101 permit tcp any any eq www
> > > > access-list 101 permit tcp any eq www any <This is for web
> > > > traffic leaving
> > > > the site correct ?>
> > > >
> > > > How do they arrive at 15000 and 10000 respectively ?
> > >
> > > [snip]
> > >
> > > Good observation.
> > >
> > >
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/
> > > fqos_c/fqcprt4/qcfpolsh.htm#1000977
> > >
> > > The above reference on the Doc CD gives the CAR formula as:
> > > <quote>
> > > Recommended Burst Values
> > > Cisco recommends the following values for the normal and extended
> > burst
> > > parameters:
> > >
> > > normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds
> > > extended burst = 2 * normal burst
> > > </quote>
> > >
> > > Here are the calculations (commas added for readability - my
> apologies
> > > to Europeans and others who don't use commas to break up the
> thousands
> > > ;-)
> > >
> > > configured rate = 30,000,000 bps
> > > normal burst = 30000000/8 * 1.5 = 5,625,000 bytes
> > > extended burst = 2 * 5625000 = 11,250,000 bytes
> > >
> > > configured rate = 10,000,000 bps
> > > normal burst = 10000000/8 * 1.5 = 1,875,000 bytes
> > > extended burst = 2 * 1875000 = 3,750,000 bytes
> > >
> > > Vegesna is obviously *not* using this formula. Maybe there is a
> > > saturation point or ceiling for burst size? (This is no more than
a
> > > SWAG.)
> > >
> > > Perhaps the "experts" will chime in ...
> > >
> > > Jonathan
> > >
> > >
> > >
> >
>
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