From: Filyurin, Yan (yan.filyurin@eds.com)
Date: Mon Apr 02 2007 - 19:02:09 ART
Written exam guide by Odom nicely explains this and I will check it as
soon as I get home. If I remember correctly when do you do shape peak
you specify 512000bps as the CIR. You can also specify BC and BE based
on which time interval gets calculated, but assuming you don't it will
use the default, which in some cases in 32Mms or 4ms (in case of
distributed) and so based on that BC will get calculated and then the
numbers get plugged in and you also get the burst size.
So in this case the traffic is throttled to the 300kbps on the interface
and before the traffic gets onto the queue it is getting shape to that
peak rate. As far as I know shaping takes place before the queuing. Ad
all the typical rules of shaping such as token bucket apply.
Can someone double check what I said, as I am definitely going to do
that. :)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gina Lopez
Sent: Monday, April 02, 2007 4:43 PM
To: ccielab@groupstudy.com
Subject: shape peak command
Hi everyone,
I am trying to figure out the shape peak command. When I use this
command, what behavior should I expect from the router? I have looked
through reference books, documentation and even searched through group
study archives and still can't get a consensus. Any help will be a big
help!
Cisco documentation gives this type of example throughout:
The following example uses peak rate shaping to ensure a bandwidth of
300 kbps but allow throughput up to 512 kbps if enough bandwidth is
available on the interface:
bandwidth 300
shape peak 512000
However, this seems to contradict the formula that is always a couple of
paragraphs above:
Peak rate shaping configures the router to send more traffic than the
CIR. To determine the peak rate, the router uses the following formula:
peak rate = CIR(1 + Be / Bc)
Thanks much!
Gina
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