From: Godswill Oletu (oletu@inbox.lv)
Date: Sun Jul 16 2006 - 19:51:40 ART
Victor,
The formular you provided is the correct one for calculating Be, CIR, etc.
You can even do a reverse computation and arrive at the same formula when
you allow the algorithm to calculate the values for you.
EG: In the other thread 'Congestion Avoidance Question' we were both
diserting a moment ago, if you look at the result of my configurations for:
>shaping average 128000
The router calculated the following values for me:
Bc=7936, Be=7936, Tc=62, we already know that CIR=128k & AR=0
If you flag any of the parameters above as 'unknown' and plug the other
values into any of your formulars, you will get the unknown. This is a good
way making sure one is correct.
This might not be the answer you are looking for but, the good and
recommended value of Bc, Be is not to configure it, allow the router to do
the computation for you.......
R3(config)#policy-map news
R3(config-pmap)#class class-default
R3(config-pmap-c)#shape average 128000 ?
<256-154400000> bits per interval, sustained. Needs to be multiple of
128.
Recommend not to configure it, the algorithm will find
out
the best value <-----Recommended Value of Be.
<cr>
R3(config-pmap-c)#shape average 128000 2000 ?
<0-154400000> bits per interval, excess. Needs to be multiple of 128. Bc
will be used if you don't configure it.
<cr>
R3(config-pmap-c)#shape average 128000 2000
HTH
Godswill Oletu
CCIE #16464
----- Original Message -----
From: "Victor Cappuccio" <cvictor@protokolgroup.com>
To: "'Chris Lewis'" <chrlewiscsco@gmail.com>; "'Kay D'" <krsna83@gmail.com>
Cc: "'Montgomery, Jerry'" <jerry.montgomery@eds.com>;
<ccielab@groupstudy.com>
Sent: Sunday, July 16, 2006 2:16 PM
Subject: RE: Shaping Average / Peak vs. Policing
> Hi Cris,
> How does the BE exactly is calculated?
>
> Ok the formulas I have seen so far is that CIR = Bc/Tc, and that Be =
> (AR-CIR) * Tc/1000
>
> BE in average shaping is sent at the first time interval + the BC, but I
> have seen discussions that this could affect critical traffic, and is
> evident because the traffic is stored at the BE Bucket, waiting fot the
time
> to Burst (the first Time interval in this situation)
>
> Is there any good recommendation for setting the BE Value?
> Any personal note about this?
>
> Thanks
> Victor.-
> (Target Rate, Be, BC = yes this are in Bits)
>
> -----Mensaje original-----
> De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de
Chris
> Lewis
> Enviado el: Domingo, 16 de Julio de 2006 02:00 p.m.
> Para: Kay D
> CC: Montgomery, Jerry; ccielab@groupstudy.com
> Asunto: Re: Shaping Average / Peak vs. Policing
>
> If you define a Be value, shape average will allow traffic in addition to
Bc
> if credit has built up. Bc (if used fully) allows the shaper to transmit
at
> CIR, so in the case described above, shape average does allow excess
traffic
> as long as Be has a non zero value.
>
> Chris
>
>
> On 7/16/06, Kay D <krsna83@gmail.com> wrote:
> >
> > Hi ,
> > Still confused with whether "shape average " would allow excess
> > traffic if credits are available or does it send only in the first
> interval
> > . Please confirm and i can have a good sleep :)
> >
> > TIA
> > Kay D
> >
> > On 7/12/06, Montgomery, Jerry <jerry.montgomery@eds.com> wrote:
> > >
> > > Chris,
> > >
> > > Thanks for the link. The light bulb just came on!!!!
> > >
> > > Thanks.
> > >
> > >
> > > Respectfully,
> > > Jerry Montgomery, CCDP, CCNP, CCDA, & CCNA
> > >
> > > -----Original Message-----
> > > From: Chris Lewis [mailto: chrlewiscsco@gmail.com]
> > > Sent: Tuesday, July 11, 2006 2:13 PM
> > > To: Montgomery, Jerry
> > > Cc: Joe Gagznos; ccielab@groupstudy.com
> > > Subject: Re: Shaping Average / Peak vs. Policing
> > >
> > >
> > > Please read over the following:
> > >
> > > http://www.cisco.com/warp/public/125/traffic_shaping_6151.html
> > >
> > > Shape peak does send Bc plus Be at every interval, contrary to my
> > > initial post.
> > > If things rae still unclear to you after reading this link, post
again.
> > >
> > > Cheers
> > >
> > > Chris
> > >
> > >
> > > On 7/11/06, Montgomery, Jerry < jerry.montgomery@eds.com> wrote:
> > > Good morning, Chris,
> > >
> > > What is the main difference between shape average and shape peak?
> > >
> > > I am trying to answer the following scenario:
> > >
> > > Limit all traffic leaving FA0/0 with IP Precedence of 128K. Do not
use
> > > policing or rate-limiting.
> > >
> > > Sometimes I convince myself that "shape average 128000 16000 0" is the
> > > answer (assuming Tc=125ms). And then sometimes I convince myself that
> > > "shape peak 128000" is the answer (default to Bc and Be).
> > >
> > > Any inside as to what the difference between "shape average" and
"shape
> > > peak" are?
> > >
> > > Also, can you send me a link regarding Be being sent in addition to Bc
> > > on the first interval of a second only? I did not find that
information
> > > explicitly stated.
> > >
> > > Thanks in advance.
> > >
> > > Respectfully,
> > >
> > > Jerry Montgomery
> > >
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> > > Chris Lewis
> > > Sent: Wednesday, July 05, 2006 9:27 AM
> > > To: Joe Gagznos
> > > Cc: ccielab@groupstudy.com
> > > Subject: Re: Shaping Average / Peak vs. Policing
> > >
> > >
> > > Shape average does not allow Bc + Be to be sent every interval.
> > >
> > > Shape average allows Be to be sent in addition to Bc on the first
> > > interval of a second only, also the shaper needs to have built up
credit
> > > in previous intervals to use Be. The effect of Be in shape average is
to
> > > allow the shaper to achieve CIR over a long period of time,
> > > accommodating periods of lull where less than CIR is sent in one
second,
> > >
> > >
> > > with an additional Be amount of data in a later period should the
credit
> > > be available and the shaper needing to send more data.
> > >
> > > Chris
> > >
> > >
> > > On 7/4/06, Joe Gagznos < joegagznos@comcast.net> wrote:
> > > >
> > > > I am trying to find another way to limit outbound traffic through an
> > > > interface similar in manner to policing. I understand that
> > > > functionally the two are different. With shaping you are going to
be
> > > > queuing excess traffic
> > > > to a predetermined rate where with policing you are going to be
> > > executing
> > > > some kind of action on traffic that exceeds the contract (usually
> > > > dropping).
> > > >
> > > > For comparison purposes, I have configured shaping and policing on
two
> > >
> > > > separate subinterfaces in the following manner:
> > > >
> > > > interface Ethernet0/0.1
> > > > encapsulation dot1Q 10
> > > > ip address 10.1.1.1 255.255.255.0
> > > > service-policy output shape
> > > >
> > > > interface Ethernet0/0.2
> > > > encapsulation dot1Q 20
> > > > ip address 10.1.2.1 255.255.255.0
> > > > service-policy output police
> > > >
> > > > Both interfaces are configured to limit traffic to no more than 2.5
> > > > Mbps as
> > > > follows:
> > > >
> > > > policy-map police
> > > > class class-default
> > > > police 2500000 conform-action transmit exceed-action drop
> > > >
> > > > policy-map shape
> > > > class class-default
> > > > shape average 2500000
> > > >
> > > > What I find is that the shaping interface initializes the parameters
> > > > as
> > > > follows:
> > > >
> > > > R1#sh policy-map interface e0/0.1
> > > > Ethernet0/0.1
> > > >
> > > > Service-policy output: shape
> > > >
> > > > Class-map: class-default (match-any)
> > > > 19 packets, 1729 bytes
> > > > 5 minute offered rate 0 bps, drop rate 0 bps
> > > > Match: any
> > > > Traffic Shaping
> > > > Target/Average Byte Sustain
> > > > Excess Interval Increment
> > > > Rate Limit bits/int bits/int
> > > (ms)
> > > > (bytes)
> > > > 2500000/2500000 15000 60000 60000 24 7500
> > > >
> > > > Adapt Queue Packets Bytes Packets Bytes
> > > Shaping
> > > > Active Depth Delayed Delayed
Active
> > > > - 0 19 1729 0 0 no
> > > >
> > > > A couple things to note here - Be is initialized to the same value
as
> > > > Bc of 60000 (or 7500 bytes). The byte limit is 15000 bytes, though.
> > > > This must mean that the byte limit is initialized to Bc+Be=15000.
> > > > With a 24 ms interval, does this mean that the interface will send 5
> > > > Mbps (15000 * 8 bits
> > > > / byte * 1 sec/.024 = 5000000) instead of the contracted 2.5 Mbps?
> > > If
> > > > shape average is allowing the interface to transmit Bc+Be each
> > > interval,
> > > > then how does this differ from configuring shape peak which
> > > accomplishes
> > > > the
> > > > same thing?
> > > >
> > > > With policing it appears that things are much more straightforward.
> > > >
> > > > R1#sh policy-map int e0/0.2
> > > > Ethernet0/0.2
> > > >
> > > > Service-policy output: police
> > > >
> > > > Class-map: class-default (match-any)
> > > > 107 packets, 7473 bytes
> > > > 5 minute offered rate 0 bps, drop rate 0 bps
> > > > Match: any
> > > > police:
> > > > cir 2500000 bps, bc 78125 bytes
> > > > conformed 63 packets, 4305 bytes; actions:
> > > > transmit
> > > > exceeded 0 packets, 0 bytes; actions:
> > > > drop
> > > > conformed 0 bps, exceed 0 bps
> > > >
> > > > Thanks for any response!
> > > >
> > > > Joe Gagznos
> > > >
> > > >
This archive was generated by hypermail 2.1.4 : Tue Aug 01 2006 - 07:13:47 ART