From: Paglia, John (USPC.PCT.Hopewell) (JPaglia@xxxxxxxxxxxxx)
Date: Wed Aug 28 2002 - 17:50:58 GMT-3
I always thought the official Cisco instruction for FRTS was as follows
(given the standard 1/8 Tc)....
CIR=64000 (provided)
AR=96000 (Provided)
BC=8000 (CIR/Tc)
BE=4000 (AR-CIR/Tc)
...which would go with 'option 2', I believe.
I never liked this because this method leaves unused bandwidth, as the
12000x1+8000x7=68000, but I was led to believe in my reading that this is
what Cisco 'recommends'.
Please correct me if I've misled myself.
Pags
> -----Original Message-----
> From: Volkov, Dmitry (Toronto - BCE) [SMTP:dmitry_volkov@ca.ml.com]
> Sent: Wednesday, August 28, 2002 3:59 PM
> To: 'Colin Barber'; Bauer, Rick
> Cc: ccielab@groupstudy.com
> Subject: RE: I need FRTS help or review - TIME TO VOTE
>
> > -----Original Message-----
> > From: Colin Barber [mailto:Colin.Barber@telewest.co.uk]
> > Sent: Wednesday, August 28, 2002 3:30 PM
> > To: Bauer, Rick; ccielab@groupstudy.com
> > Subject: RE: I need FRTS help or review - TIME TO VOTE
> >
> >
> > I think the confusion is:
> >
> > can (BC+BE)/Tc be greater than AR as Jim is saying because
> > the interface
> > will buffer the excess or
> >
> > (BC+BE)/Tc <= AR because the burst has to be transmitted within one Tc
> >
> > Your link states that the parameters control the rate of
> > traffic onto the
> > interface but not onto the line so is the interface buffering
> > any excess and
> > can you have a large excess?
> >
> >
> > To put it another way: if your CIR is less than the access
> > speed of the
> > interface and you wish to burst to the full access speed, do
> > you work out BE
> > so that the access rate is achieved only in the first Tc or
> > the access rate
> > is achieved over a full second?
> >
> > I think we need a vote on the two options - I'm for option 2
> >
> > For example:
> >
> > CIR = 64000
> > Access rate = 96000
> > Tc = 1/8th sec
> > BC=8000
> >
> > To burst up to the AR what is the value of BE?
> >
> > option 1 BC=32000 (8*BC)+BE = 96000
>
> !!!!!!!!!! BE=32000 not BC !!!!
>
> >
> > option 2 BC=4000 at one Tc BC+BE=12000*Tc = 96000
>
> !!!!!!!!!! BE=4000 not BC !!!!
>
> >
> > Colin
> >
> > -----Original Message-----
> > From: Bauer, Rick [mailto:BAUERR@toysrus.com]
> > Sent: 28 August 2002 19:55
> > To: 'ccielab@groupstudy.com'
> > Subject: RE: I need FRTS help or review
> >
> >
> > This should help. The first couple of lines will answer your
> > question in
> > regard to CIR, BE, BC.
> >
> > http://www.cisco.com/warp/customer/125/21.shtml
> >
> > Rick, #9482
> >
> > -----Original Message-----
> > From: Volkov, Dmitry (Toronto - BCE) [mailto:dmitry_volkov@ca.ml.com]
> > Sent: Wednesday, August 28, 2002 2:07 PM
> > To: 'Jim Brown'; 'Colin Barber'; 'Omer Ansari'
> > Cc: 'ccielab@groupstudy.com'
> > Subject: RE: I need FRTS help or review
> >
> >
> > Jim,
> >
> > You are right traffic will be delayed and sent within 9th Tc interval
> > (assuming Tc=1/8 sec).
> > But Be is still Be - it is number of bits, and Be+Bc =< Port Speed
> > (clocking) * Tc.
> >
> > We have to put actual number in config.
> >
> > 40000 bits will not be transmitted during 1st Tc - only 12000 bits.
> > Other bits will be delayed until 9th Tc.
> >
> > Be - number of bits will be transmitted within 1st Tc ==> be = 12000
> > -8000(Bc) = 4000 bits
> >
> > and this number 4000 we have to put in config as Be. The
> > other bits will be
> > delayed / dropped, whatever.
> >
> > I'm not 100% sure about it, but I got this logic from CCO.
> >
> > Colin right - the documentation on this subj is very unclear.
> >
> > This subj is like religion for me - believe or not believe :)
> >
> > Dmitry
> >
> > > -----Original Message-----
> > > From: Jim Brown [mailto:Jim.Brown@caselogic.com]
> > > Sent: Wednesday, August 28, 2002 11:35 AM
> > > To: 'Colin Barber'; 'Omer Ansari'; 'ccielab@groupstudy.com'
> > > Subject: RE: I need FRTS help or review
> > >
> > >
> > > You do not necessarily need 320Kps available during the first
> > > interval. The
> > > packets are software queued before they are placed onto the
> > > TxRing. This is
> > > the whole idea behind shaping.
> > >
> > > They are not placed on the wire at exactly the same speed
> > > designated per TC
> > > interval.
> > >
> > > List, if I'm way off base please correct me and help me see
> > the light.
> > >
> > > -----Original Message-----
> > > From: Colin Barber [mailto:Colin.Barber@telewest.co.uk]
> > > Sent: Wednesday, August 28, 2002 9:09 AM
> > > To: 'Omer Ansari'; 'ccielab@groupstudy.com'
> > > Subject: RE: I need FRTS help or review
> > >
> > >
> > > What's the access speed of the interface? If it's 96k then this is
> > > incorrect. In the first time slot BC+BE=40000. For that
> > > amount of data to be
> > > transferred in the first timeslot the access speed will need to be
> > > 40000*8=320kbps.
> > >
> > > Colin
> >
> > --------------------------------------------------------------
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