From: David Luu (wicked01@xxxxxxxxxxxxx)
Date: Tue Jul 16 2002 - 19:36:47 GMT-3
i see what you are trying to get at now...you are trying to build up tokens
for your next burst, am i correct?...that is why i kept saying "if there
are enough tokens available"
At 07:30 PM 7/16/2002 -0300, Carlos G Mendioroz wrote:
>David,
>the problem is that Be will be exhausted after one second. If you don't
>go
>below CIR, then you will not be able to transmit any more excess bursts.
>
>With your params (AR=64kbps,CIR=32kpbs,Bc=4000, Ec=32000) , a ttcp
>of 60x8192bytes takes 125 seconds. That's an efective 32kbps.
>
>
>
>David Luu wrote:
> >
> > "Be" should be written in bits, i got carried away typing bps at the
> time...
> >
> > i said that "Be" is sent out in the FIRST interval of EVERY SECOND if
> > enough tokens are available...
> >
> > "burst excess" can be sent out in more than 1 interval, but it CANT take
> > place in the SAME second...assuming a Tc of 125ms which gives us 8
> > intervals PER second, it can be sent out on the 1st, 9th, 17th, etc
> > interval, the 1st interval will take place in the 1st second, the 9th
> > interval will take place in the 2nd second, the 17th interval will take
> > place in the 3rd second...
> >
> > now for the Be=(AR-CIR)*Tc...
> > assume AR=64kbps, CIR=32kbps, and a Tc of 125ms
> > this would make Be = 4kb according to the formula you are using
> > now do CIR+Be=36kb, remember that Be is sent ONCE a second if enough tokens
> > are available
> > so the max you can send in 1 second is 36kb
> > you are not effectively using your AR...64kb-36kb=28kb of room to burst
> >
> > to burst from your CIR to AR you would want to use a Be of 32kb
> > now CIR+Be=64kb=AR
> >
> > At 04:33 PM 7/16/2002 -0300, Carlos G Mendioroz wrote:
> > >Guoqi Cui wrote:
> > > >
> > > > As I understand CIR and BE are in different unit.
> > >
> > >Yes indeed.
> > >
> > > > We can not say set BE=32000 bps. BE should be in
> > > > unit of bits. As for the example, 32000 is the extra
> > > > link speed to handle extra traffic beyond CIR. The
> > > > formula to calculate BE is: (AR-CIR)*Tc. Tc is one
> > > > slot time interval. You can set BE higher than
> > > > (AR-CIR)*Tc, what is the use of it? Sinece AR is the
> > > > maximum rate the link can provide, after garantee CIR
> > > > only (AR-CIR) left.
> > >
> > >There is only AR - CIR left but in each Tc!
> > >You can use your "excess burst" in many Tc's.
> > >
> > >As I said in the example, even though you have only 4000
> > >bits left to transmit above CIR, you can actually transmit
> > >one full minute at AR given that you have enough Be.
> > >
> > >Please take the time to make the experiment.
> > >Or read some book (e.g. Tannenbaum's computer metworks)
> > >about the dual leaky bucket algorithm. That's what it is.
> > >
> > >Regards,
> > >
> > > >
> > > > As for David, you set BE as 32000bps, this is
> > > > different from BE's definition, you give a rate, BE
> > > > should be in bits.
> > > >
> > > > --- Carlos G Mendioroz <tron@huapi.ba.ar> wrote:
> > > > > David,
> > > > > I think this is not quite right, or I am
> > > > > misunderstanding you.
> > > > >
> > > > > To be safe, it is ok to set Be to a value >> AR/Tc.
> > > > >
> > > > > It is my understanding that Be is how much data you
> > > > > can transmit over
> > > > > your CIR,
> > > > > as you "eat" burst tokens. But you can eat them in
> > > > > more than one Tc.
> > > > >
> > > > > Here an example everyone can run to see the
> > > > > difference:
> > > > >
> > > > > CIR = 32 kbps
> > > > > Bc = 4000 b
> > > > > Tc = .125 s (automatically computed)
> > > > > Be = 1920000 b
> > > > > Ar = 64 kbps (Access rate, i.e. clockrate)
> > > > >
> > > > > This will transmit at 64kbps for one minute and then
> > > > > drop to 32k.
> > > > > Try it with ttcp, send 60 x 8192 bytes, it will take
> > > > > some 75 seconds...
> > > > >
> > > > > http://www.cisco.com/warp/customer/125/21.shtml has
> > > > > more info.
> > > > >
> > > > > Regards,
> > > > >
> > > > >
> > > > > David Luu wrote:
> > > > > >
> > > > > > like i said in a previous post...
> > > > > > "Be" sends excess data in the FIRST interval if
> > > > > there are enough tokens, it
> > > > > > does not send it in the other intervals
> > > > > >
> > > > > > take the bottom example...
> > > > > > port speed = 64000bps
> > > > > > cir = 32000bps
> > > > > > mincir = 16000bps
> > > > > > bc = 4000bps
> > > > > > be = 32000bps
> > > > > >
> > > > > > first we will start off with "Bc", to get "Bc" we
> > > > > divide 1 second (1000ms)
> > > > > > by the time interval (which is 125ms in this
> > > > > case), which is 1000ms divided
> > > > > > by 125ms = 8...this gives us 8 intervals, so a
> > > > > 32000bps cir divided by 8
> > > > > > gives us a "Bc" of 4000bps
> > > > > >
> > > > > > again, "Be" sends excess data in the FIRST
> > > > > interval if there are enough
> > > > > > tokens, it does not send it in the other
> > > > > intervals...to send data at the
> > > > > > maximum rate the port can handle, we take the port
> > > > > speed of 64000bps minus
> > > > > > the cir of 32000bps...this leaves us with 32000bps
> > > > > to send in the first
> > > > > > interval...
> > > > > >
> > > > > > if we were to have a "Be" of 4000bps, the max rate
> > > > > we can send is cir + be
> > > > > > (32000+4000), which equals 36000bps, remember that
> > > > > "Be" is only sent out in
> > > > > > the FIRST interval if there are available tokens
> > > > > >
> > > > > > with a Tc of 125ms, it gives us 8 intervals
> > > > > > with a Tc of 10ms, it gives us 100 intervals
> > > > > >
> > > > > > once again i have to stress this, "Be" is only
> > > > > sent out in the FIRST
> > > > > > interval if tokens are available...with a Tc of
> > > > > 125ms or 10ms, "Be" will
> > > > > > still only be sent out ONE time every second
> > > > > (1000ms)
> > > > > >
> > > > > > hope this clears up any confusion you may have
> > > > > with "Be" and "Bc"
> > > > > >
> > > > > > At 01:33 AM 7/16/2002 +0500, Ahmed Mamoor Amimi
> > > > > wrote:
> > > > > > >aaaahhhh !! atleast ur with me... heheheeh...
> > > > > this is what i have beening
> > > > > > >saying but not getting a very difinite answer
> > > > > from the group why they have
> > > > > > >used 32000 as be in power session. if bc is
> > > > > multipy by 0.125 then be should
> > > > > > >also be multiply by 0.125 ... why 1 sec
> > > > > > >
> > > > > > >-Mamoor
> > > > > > >
> > > > > > >
> > > > > > >----- Original Message -----
> > > > > > >From: Guoqi Cui <guoqicui@yahoo.com>
> > > > > > >To: Bruce Williams
> > > > > <bruce@williamsnetworking.com>; Lab Candidate
> > > > > > ><labccie@yahoo.com>; Ahmed Mamoor Amimi
> > > > > <mamoor@ieee.org>
> > > > > > >Cc: <ccielab@groupstudy.com>
> > > > > > >Sent: Monday, July 15, 2002 9:49 PM
> > > > > > >Subject: RE: FRTS want to nail it down !!
> > > > > > >
> > > > > > >
> > > > > > > > The FRTS parameters are quite confusing.
> > > > > > > > CIR, MINCIR is in unit of bps
> > > > > > > > BC, BE is in unit of bits
> > > > > > > >
> > > > > > > > If BE is set as: port_speed minus-cir
> > > > > > > > it will hava a unit of bps,
> > > > > > > >
> > > > > > > > Do Tc is assumed to be 1 sec?
> > > > > > > >
> > > > > > > > For this case( Tc=0.125 sec),
> > > > > > > >
> > > > > > > > BE should be set as 32000/8=4000.
> > > > > > > >
> > > > > > > >
> > > > > > > > --- Bruce Williams
> > > > > <bruce@williamsnetworking.com>
> > > > > > > > wrote:
> > > > > > > > > If the available bandwidth is 32000, then
> > > > > dont we
> > > > > > > > > still need to multiply it
> > > > > > > > > by .0125 to get the bits per Tc?
> > > > > > > > >
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: nobody@groupstudy.com
> > > > > > > > > [mailto:nobody@groupstudy.com]On Behalf Of
> > > > > > > > > Lab Candidate
> > > > > > > > > Sent: Sunday, July 14, 2002 1:03 AM
> > > > > > > > > To: Ahmed Mamoor Amimi
> > > > > > > > > Cc: ccielab@groupstudy.com
> > > > > > > > > Subject: Re: FRTS want to nail it down !!
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > Mamoor,
> > > > > > > > >
> > > > > > > > > This is obvious, since you said the port
> > > > > speed is
> > > > > > > > > 64000 and cir is 32000,
> > > > > > > > > if you want to utilized the most of your
> > > > > available
> > > > > > > > > bandwidth for burst
> > > > > > > > > purpose, the be would be equal to port_speed
> > > > > minus
> > > > > > > > > cir, hence 32000 bps.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > I was reading the power-session 2002, here
> > > > > on page
> > > > > > > > > 66 they have given the
> > > > > > > > > values like :
> > > > > > > > >
> > > > > > > > > Port Speed: 64000 Bps
> > > > > > > > > CIR : 32000 Bps (Average Rate of Traffic
> > > > > Without
> > > > > > > > > Congestion)
> > > > > > > > > Mincir: 16000 Bps (Average Rate of Traffic
> > > > > With
> > > > > > > > > Congestion)
> > > > > > > > > Bc: 4000 Bps (Amount of Data Sent Per
> > > > > Interval)
> > > > > > > > > Be: 32000 Bps (Amount of Excess Allowed Once
> > > > > Credit
> > > > > > > > > Has Built Up)
> > > > > > > > >
> > > > > > > > > interface Serial0
> > > > > > > > > ip address 10.10.10.1 255.255.255.0
> > > > > > > > > encapsulation frame-relay
> > > > > > > > > frame-relay traffic-shaping
> > > > > > > > > frame-relay class ccie
> > > > > > > > >
> > > > > > > > > map-class frame-relay ccie
> > > > > > > > > frame-relay adaptive-shaping becn
> > > > > > > > > frame-relay cir 32000
> > > > > > > > > frame-relay mincir 16000
> > > > > > > > > frame-relay bc 4000
> > > > > > > > > frame-relay be 32000
> > > > > > > > >
> > > > > > > > > Can someone explain why Be = 32000 , why not
> > > > > Be =
> > > > > > > > > 32000 * 0.125 = 4000
> > > > > > > > >
> > > > > > > >
> > > > >
This archive was generated by hypermail 2.1.4 : Sat Sep 07 2002 - 19:36:33 GMT-3