From: Chris Hugo (chrishugo@xxxxxxxxx)
Date: Thu Aug 29 2002 - 16:08:38 GMT-3
Sorry folks if you got my post twice. I just want to make sure I get my vote in
:) .... I received a fail delivery at 8:30 AM PST on my last post
chris hugo
Hi All,
I will still stand on option 2 all the way. I will try and test this out with
TTCP.
OT:Our discussion is balancing between two weights.
One is math and the other is practical. This is also seen a lot in electronics
where your calculation is off-base from the measurment you took in the lab. The
ir is no way that you can put a answer that is a little off on your paper and t
hink your gonna get marked right.
Maybe you thought you were right since you also factored in the +/-5% that you
saw when you labbed it up. But the teacher is also looking for the number that
HE showed YOU how to get.
kind regards,
chris hugo
Carlos G Mendioroz wrote:Comments inline...
"Volkov, Dmitry (Toronto - BCE)" wrote:
>
> Carlos,
>
> Can You point us this place "where it says BE can be larger than AR * Tc" ?
>
> Do You mean this from http://www.cisco.com/warp/customer/125/21.shtml ?:
> Excess Burst Size (Be)
> The number of non-committed bits (outside of CIR) that are still accepted by
> the Frame Relay switch but are marked as eligible to be discarded (DE).
>
> The token bucket is a 'virtual' buffer. It contains a number of tokens,
> enabling you to send a limited amount of data per time interval. The token
> bucket is filled with Bc bits per Tc. The maximum size of the bucket is Bc +
> Be. If the Be is very big and, if at T0 the bucket is filled with Bc + Be
> tokens, you can send Bc + Be bits at the access rate. This is not limited by
> Tc but by the time it takes to send the Be. This is a function of the access
> rate.
>
> "If the Be is very big .." - I guess it is not about Be, but should be read
> "If the BURST is very big.."
NO, its ok as it is. If Be is very big, meaning that you configure
it in the shapping as a large number.
>
> Now about this "This is not limited by Tc but by the time it takes to send
> the Be. This is a function of the access rate."
> If burst is bigger than Be+Bc, bits above Be+Bc will be sent as soon as
> token bucket has enough tokens - the don't have to be sent within Tc - Token
> bucket mechanism regulates when to send them
As long as we have tokens available, it will transmit at AR.
The token bucket is be+bc in size, it's loaded with bc bits
every Tc and drained with as many bits you have to send.
You do not have data to send, you can acquire as many as Be+Bc.
You have plenty of data to send ? Then you transmit at AR untill
you run out of tokens. As you get tokens at Bc/Tc rate, after
you empty your token bucket, you'll continue to transmit at Bc/Tc
>
> As Donny Mateo showed : each Tc interval, token bucket refilled with Bc
>
> Srinivas Vegesna IP Quality of service: page 188 :
>
> Burst size (Bc) is the amount of data added to the token bucket of size
> (Bc+Be) at each measuring interval, Tc. Tc is defined as Bc/CIR. Excess
> burst size Be is amount of excess burst of data allowed to be sent during
> the first interval when the token bucket is full.
> When a new packet arrives, it is queued into the output queue and scheduled
> for transmission based on queue scheduler used, such as WFQ or FIFO. A
> packet scheduled for transmission by the scheduler is transmitted only if
> enough tokens are available in the bucket equivalent to the scheduled
> packet. After a conforming packet is transmitted, an equivalent amount of
> tokens are removed from the bucket.
> If not all Bc bytes are sent in a Tc interval, You can transmit the unused
> bytes in the subsequent interval along with the new credit for Bc bytes.
> Hence, in a Tc interval during which there is less than Bc traffic, the
> credit can increase to an upper bound of Bc + Be for the next subsequent
> interval.
> If serious load sets in and the token bucket is full, you can send Be + Bc
> bytes in the first interval and Bc bytes in each subsequent interval until
> congestion conditions ease. As you can see, you can throttle to the CIR
> equation at times of congestion.
>
> There is very good diagram on page 189.
This is what I'm also saying. This does not prevent you from having
Be larger than what you can transmit in one Tc.
>
> Dmitry
>
> > -----Original Message-----
> > From: Carlos G Mendioroz [mailto:tron@huapi.ba.ar]
> > Sent: Thursday, August 29, 2002 5:49 AM
> > To: Colin Barber
> > Cc: Jim Brown; ccielab@groupstudy.com
> > Subject: Re: I need FRTS help or review - TIME TO VOTE
> >
> >
> > People,
> > I'm forwarding an old message on the theme. BTW, I'm with option 1, as
> > it is
> > clearly stated (and demostrated) below. As MADMAN says, when in doubt,
> > test it.
> >
> > Documentation in cisco is confusing to say the least, and it
> > seems that
> > parts of
> > them have been reproduced "as is" many times. There is at least one
> > place
> > (also listed below) where it says BE can be larger than AR * Tc.
> >
> > HTH.
> >
> > >>>>>>
> > Subject:
> > Re: FRTS want to nail it down !!
> > Date:
> > Tue, 16 Jul 2002 17:53:19 -0300
> > From:
> > Carlos G Mendioroz
> > To:
> > "Paglia, John (USPC.PCT.Hopewell)"
> > References:
> > 1
> >
> >
> > John,
> > take a look at http://www.cisco.com/warp/customer/125/21.shtml
> > There it's a litle more clear that the Be does not have to enter
> > in one Tc.
> >
> > I really don't have much else to say, and I'm starting to reiterate
> > myself, which is no good. Please do the experiment of setting the
> > params as I said (it will take you 5 to 20 minutes) and then
> > a lot of thinking :-)
> >
> > Regards,
> > -tron
> >
> >
> > "Paglia, John (USPC.PCT.Hopewell)" wrote:
> > >
> > > OK, now I'm getting confused on this point, because when I
> > read Cisco
> > > Documentation, I was led to believe that the Be is ONLY
> > sent during the
> > > first time cycle. Thus, for example....
> > >
> > > 125 ms
> > > max= 64k
> > > CIR= 48k
> > > mincir= 24k
> > > I was thinking that if the above is true, that...
> > >
> > > Bc= 6k (48k/8 (1sec*.125))
> > > Be= 16k (max-above formula)
> > >
> > > 6k (Bc) * 8 # of time cycles) + 16k (remainder sent in
> > first time cycle) =
> > > 64K
> > >
> > > Please assist,
> > > Pags
> > >
> > > > -----Original Message-----
> > > > From: Carlos G Mendioroz [SMTP:tron@huapi.ba.ar]
> > > > Sent: Tuesday, July 16, 2002 3:34 PM
> > > > To: Guoqi Cui
> > > > Cc: David Luu; Ahmed Mamoor Amimi; Bruce Williams; Lab
> > Candidate;
> > > > ccielab@groupstudy.com
> > > > Subject: Re: FRTS want to nail it down !!
> > > >
> > > > 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 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
> > > > > > > >To: Bruce Williams
> > > > > >
; Lab Candidate
> > > > > > > >; Ahmed Mamoor Amimi
> > > > > >
> > > > > > > >Cc:
> > > > > > > >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
> > > > > >
> > > > > > > > > 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
> > > > > > > > > >
> > > > > > > > >
> > > > > >
> > > > >
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