From: simon hart (simon@harttel.com)
Date: Wed Oct 26 2005 - 16:25:54 GMT-3
Hi Jim,
Your solution follows the correct math, and yes the penalty is 1000.
However I do not believe that there is an answer to this question that makes
sense. For example:
3 flaps in the first 4 seconds will be approximately 2890 penalty points at
the 4 second point.
Now the fourth flap occurs at 29 seconds, the original 2890 penalty will
have reduced to approx 1445 and now add 1000 penalty you will get 2445.
Therefore the interface does not get dampened if suppress-threshold is 2900,
after 4 flaps in 30 seconds.
However if you reduce the suppress-threshold to below 2900, in the above
example the interface will get dampened after 3 flaps, thus not achieving
the objective either.
Thus the scenario is not achievable. However I await to be proved wrong -
which does happen a lot :)
Simon
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Balogh, Jim
Sent: 26 October 2005 20:08
To: ccielab@groupstudy.com
Subject: Dampening command
I am working on a practice lab, and it asks that I remove an interface
from the routing table if it flaps 4 times in 30 seconds. I plan to use
the DAMPENING interface command. When looking at the DocCD, it doesn't
mention what the value of the penalty is? I am assuming 1000.
So, here is what I am wresting with......I don't know at what frequency
the flaps will occur (or do I care?)? For example, lets say with all
default settings, my flaps occur every 2 seconds. I have roughly
estimated what the decay would be:
Flap 1: time 0 seconds, penalty is 1000 + current penalty of
approximately 0 = 1000
Flap 2: time 2 seconds, penalty is 1000 + current penalty of
approximately 875 = 1875
Flap 3: time 4 seconds, penalty is 1000 + current penalty of
approximately 1640 = 2640 <--now exceeds the suppress-threshold of 2000
Flap 4: time 6 seconds, penalty is 1000 + current penalty of
approximately 2310 = 3310 <--still suppressed
Now, if the flaps occur every 5 seconds:
Flap 1: time 0 seconds, penalty is 1000 + current penalty of
approximately 0 = 1000
Flap 2: time 5 seconds, penalty is 1000 + current penalty of
approximately 800 = 1800
Flap 3: time 10 seconds, penalty is 1000 + current penalty of
approximately 1440 = 2440 <--now exceeds the suppress-threshold of 2000
Flap 4: time 15 seconds, penalty is 1000 + current penalty of
approximately 1950 = 2950 <--still suppressed
So, if my math is correct, I do not care at what rate the flaps occur,
all I care is that all 4 flaps happen within 30 seconds....correct? If I
am on target so far, then to solve the problem all I need to do is
increase the suppress-threshold to approximately 2900.
Would this solve the problem:
Interface serial 0
dampening 15 1000 2900 60
TIA
Jim
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