From: Ralph (Mandela@myrealbox.com)
Date: Fri Sep 09 2005 - 11:51:01 GMT-3
Good point, Anthony.
But what if the MIB given is not a familiar type, that is, I do not know its characteristics - I'm not sure if this MIB always increase or it actually fluctuates - how does someone know whether to use delta or absolute values?
Regards
Ralph
-----Original Message-----
From: Anthony Sequeira <terry.francona@gmail.com>
To: Wireman <int_s0@earthlink.net>
Date: Fri, 9 Sep 2005 10:30:16 -0400
Subject: Re: RMON Alarms- Delta and Absolute
I think the better way to go is to look at the counter that you are
examining - not what information you are trying to gain.
Here is a quote from Brian Dennis of InternetworkExpert on this matter that
totally cleared it up for me. This quote is from their excellent Support
Forum that you get access to when you purchase the R/S Workbook.
Be sure to start using this forum if you are not already!
"Values that only increase (i.e. input packets) should use delta. These
values will never decrease and only increase so you to know the rate of
change (delta).
Values that increase and decrease (i.e. CPU utilization) should use
absolute. You want to know what absolute value is (i.e. 35% CPU utilization,
80% memory utilization, etc) and not the rate of change in these values.
Normally you don't really care if the CPU utilization increase 10% in 5
minutes because if may have jumped up from 10% to 90% and back down to 20%
in the 5 minutes. If is more important normally to know what the current CPU
utilzation is. "
On 9/8/05, Wireman <int_s0@earthlink.net> wrote:
>
> Searching through the archives I see this has been talked about, but I
> have read a few examples that have confused me.
>
> Here is what I get from it please let me know if this is the correct
> understanding :)
>
>
> Absolute=
> This is for things that I'm interested in knowing what the value is
> currently.
> For example - I want to know when my memory is 80% utilized, and I will
> check for it every 2 minutes.
>
> And Absolute can also be used to monitor something like, I want to know
> when I have processed 1,000,000 incoming packets. Something that has been
> counting up since my last reload.
>
>
> Delta=
> This is when I want to look at averages/rate of change.
> For example- This would be if I wanted to know in the last 5 minutes have
> I used 40% more of my memory.
>
> This could be useful in this situation- I have a virus that is creating
> thousands more NAT translations in just moments, and my memory went from 40%
> to 95% in 5 minutes.
>
>
> Is this right?
>
> Thanks,
>
> J Wireman
>
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