From: Chirag Arora (carora1977@gmail.com)
Date: Sun Jul 16 2006 - 16:10:32 ART
Hi Victor
What i know is that Be = Bc*Tc. In case of shaping, Tc is usually taken as
1/8 though router decides on its own the Tc value.
On 7/16/06, Victor Cappuccio <cvictor@protokolgroup.com> wrote:
>
> 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
> > > >
> > > >
> ______________________________________________________________________
> > >
> > >
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-- Chirag
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