From: Paglia, John (USPC.PCT.Hopewell) (JPaglia@NA2.US.ML.com)
Date: Mon Oct 07 2002 - 23:08:41 GMT-3
I'm not looking at the Doyle book, but if that is truly what it says, then I
have a problem with it as well. It just doesn't make logical sense!!!
Everyone agrees that Be is data that's 'above and beyond the norm', or
better put a burst, right? Then how can CIR = the physical port speed??
Wouldn't that max out the port without Be even coming into play??? Am I
being too literal???
Here are the rules I play by....
CIR = (Committed Information Rate) - average rate of data that can be
transmitted over a specific connection for a fixed period of time. Measured
in bits per second. Provided.
Bc = (Committed Burst) - maximum amount of data the network agrees to
transfer, under normal conditions, over a fixed and specific time interval.
Measured in bits per second, usually a multiple of CIR (CIR/Tc).
Be = (Excess Burst) - maximum amount of data in excess of Bc that the
network will attempt to transfer, under normal conditions, over a fixed time
interval. Measured in bits per second.
Tc = (Time Interval) - pre-determined unit of time measured in seconds per
burst. Represented by the formula Tc = Bc/CIR. 10 ms is ideal for voice,
can NOT exceed 125 ms.
MINCIR = By default equals CIR/2
HTH,
John
> -----Original Message-----
> From: Giveortake@aol.com [SMTP:Giveortake@aol.com]
> Sent: Monday, October 07, 2002 9:27 PM
> To: Svuillaume8@aol.com; ccielab@groupstudy.com
> Subject: Re: FRTS
>
> If thats what Jeff Doyle says, I say Jeff Doyle is wrong! But then
> again
> who am I (dumb guy who failed twice) That may be ok for certain
> situations,
> but does not cover all.
>
> I don't believe you can make a blanket statement like that listed below.
> Frankly its just wrong. It may be right in a "specific" scenerio but
> WRONG
> for another.
>
> CIR = Port physical speed
> Mincir= CIR ( cir provides by carrier)
> Bc= remote speed circuit /8
> Be<= port speed of the remote router
>
> Actually I think the blanket statements like this are killing people from
> understanding. What we need are a couple good scenerios to demonstrate
> real
> life situations such as over subscribing a head end, throttling back to
> certain transmit rates if BECN's received etc.......... Traffic shaping
> takes some math and some thought. Not memorize these four lines.
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