From: Scott Vermillion (scott_ccie_list@it-ag.com)
Date: Sat Dec 01 2007 - 02:19:49 ART
Hey Keith,
I can't think of an article, per se, but Odom's QoS Guide is pretty much
required reading for CCIE candidates, IMHO. You will not have any doubts
about this or other such issues if you give that a good read.
In short, just remember that shaping actually delays (buffers) exceeding
traffic in an attempt to "spool" it out at the CIR. Policing does not
perform any kind of delaying/buffering, but rather drops or remarks traffic
that is out of conformance with the defined service parameters. For this
reason, shaping is typically done outbound while policing is typically done
inbound. You would shape towards your carrier, for example, because they
would be policing inbound from you. Better to buffer up your outbound
traffic and try to spool it out during an ebb in offered load than to have
the carrier deal more harshly with it inbound. As far as lab scenarios go,
there are usually keywords in the task which help you to know which to
choose.
But again, you will not be disappointed with your investment of both time
and $$ if you buy and read that book. I'm going to read it cover-to-cover
once more before I attempt the lab in Feb...
Regards,
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
keith tokash
Sent: Friday, November 30, 2007 9:58 PM
To: ccielab@groupstudy.com
Subject: "shape average" vs police
Does anyone happen to know of a nice article explaining the difference
between
"shape average" and "police"? I'd like to clear this up, and my searches
keep
turning up configuration steps, which are far easier than understanding the
nuances of the two.
As I understand things, shaping allows some ebb and flow from the average
rate
you give it, queueing packets if possible, whereas policing is a hard drop
at
the prescribed limit.
With a few exceptions, secrecy is deeply incompatible with democracy and
with
science.
--Carl Sagan
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