Re: RMON - When would falling-threshold kick in if the alarm

From: Eric Phillips (eric@phillips.tc)
Date: Wed Jan 14 2009 - 23:19:37 ARST


Hi Hobbs,
Remember that the value being compared against the rising and falling
thresholds is the delta, aka "the change." For example, if the number of
interface errors changes from 1000 to 1005, the delta is 5. So if you check
every six minutes, and during one six minute period the number of errors
increases from 100 to 120, the rising threshold is breached because the
delta is 20, and the alert is triggered. If during the next six minute
period the number of errors increases from 120 to 121, the delta is one, and
the falling threshold is triggered.

Remember with delta RMON tracking it is not the value you see in the "show
interface" output that you are comparing, it is the DELTA, the amount
changed.

Hope that helps!

-EricP

On Wed, Jan 14, 2009 at 6:40 PM, Hobbs <deadheadblues@gmail.com> wrote:

> Hello,
>
> As I understand Delta type is used for values that only increase and
> compared over a time. If so, then when would a falling-threshold ever get
> triggered?
>
> Example:
>
> "Configure a router to monitor the number of interface errors on a
> particular interface"
>
> rmon event 7 log trap TRAP description "ifErrors have exceeded threshold"
> rmon alarm 7 ifEntry.20.3 300 delta rising-threshold 5 7 falling-threshold
> -1 7
>
> Would the falling threshold ever trigger? Errors cannot decrease...right?
>
> thanks,
>
>
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-- 
Eric M. Phillips                               Senior Network Consultant

LTI Information Technology http://www.ltiit.com 501 Avis Drive Ann Arbor, MI 48108

Phone: (734) 929-1400 Fax: (734) 929-1401

Blogs and organic groups at http://www.ccie.net



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