From: Scott Morris (swm@emanon.com)
Date: Sun Jun 12 2005 - 13:00:54 GMT-3
I'm jumping into this discussion a little late here, so forgive me if
someone has already pointed it out, but "absolute" or "delta" have to do
with a reference point, not whether something is going up or going down.
Your rising or falling thresholds have to do with the direction of
measurements.
You set up an RMON alarm to be monitored every 'x' number of seconds. The
next stage is what you do with that number. If it is an absolute number,
you simply measure that number itself with regards to your going up/down
events. If it is a delta number, you measure it in reference to the last
timed measurement and see the change value (hence "delta").
CPU utilization as an example is typically an absolute measurement.
Interface utilization, on the other hand may very well be a delta. (I don't
necessarily care that my interface is at 50% right now, but I do care if two
seconds ago I was at 1% and now I'm at 51%)
HTH,
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Roy
Dempsey
Sent: Sunday, June 12, 2005 8:05 AM
To: Hotmail
Cc: Cisco certification
Subject: Re: Absolute vs delta
Georg,
It was actually a collegue, who had read it in a lab scenario. However Brian
McGahan from IE, in a reply to the group, seems to have confirmed that I was
indeed incorrect.
It relates to whether the value being monitored can only rise, or whether it
can rise and fall. For example, the amount of errors seen on an interface
will only increase, and should use delta.
Values which rise and fall like CPU utilisation should use absolute values,
because the rate of change which delta examines isn't useful in these cases,
only the currently measured value.
I think I have paraphrased Brian correctly. If not, I apologise.
Do I understand it? I'm not sure yet....:-)
Regards
Roy
On 6/11/05, Hotmail <pauwen@hotmail.com> wrote:
> Hello Roy,
>
> I would have said the same as you, exceed means absolute, and increase
> means delta. When you say you are being told otherwise, is that from
> an exercise, or solution book ?
>
> Regards,
>
> Georg
> ----- Original Message -----
> From: "Roy Dempsey" <roy.dempsey@gmail.com>
> To: "Cisco certification" <ccielab@groupstudy.com>
> Sent: Thursday, June 09, 2005 6:14 PM
> Subject: RMON: Absolute vs delta
>
>
> > If a question asks to generate an RMON alert when the number of
> > input errors on an interface exceeds 50 per second, should you use
> > absolute or delta? This sounds like an absolute event, rather than a
> > delta event.
> >
> > If it asked you to alert when the input errors *increased* by 50 per
> > second I would have thought this was a delta event. However, I'm
> > being told differently...
> >
> > Can anyone explain how you can differentiate between them?
> >
> > Thanks
> > Roy
> >
> > ____________________________________________________________________
> > ___ Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
>
-- Regards, Roy
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