From: The Great Ryan (pv.ryan@gmail.com)
Date: Sat Oct 29 2005 - 09:34:38 GMT-3
Hi, CCIE, How are you ?
=)
Ryan
2005/10/25, simon hart <simon@harttel.com>:
> No, that would be 30 / 2000
>
> Simon
>
> -----Original Message-----
> From: Dave Temkin [mailto:dave@ordinaryworld.com]
> Sent: 25 October 2005 00:14
> To: simon hart
> Cc: Milenko Markov; ccielab@groupstudy.com
> Subject: RE: Route Dampening
>
>
> OK, so let's say it's 3 flaps in 30 seconds... How does the calculation
> work then? 30/3000?
>
>
> On Mon, 24 Oct 2005, simon hart wrote:
>
> > Hi Milenko,
> >
> > You bring up some fascinating points with regards to this suppression
> > question. However I believe the question related to interface dampening
> as
> > opposed to BGP dampening, thus the times are expressed in seconds rather
> > than minutes, thus the rate at which the penalty decreases is far more
> rapid
> > (however the overall philosophy still holds).
> >
> > So if we take the worst case scenario, do we use a suppress of 3000 ?? If
> > so the interface would be dampened after 4 flaps and not 5. Anything used
> > as a suppress-threshold of less than 4000 will mean the interface could
> get
> > dampened after 4 flaps!!!, But also means that the interface could
> > potentially not get dampened after 30 seconds.
> >
> > And you are right regarding the reuse threshold, in the example I gave
> there
> > is potential for the route to get unsurpressed within that 30 second
> period.
> > However the question does not state how long it should be surpressed for,
> so
> > becoming unsurpressed within 30 seconds should not be an issue.
> >
> > My conclusion is that it is impossible to answer this question with values
> > that will meet every criteria for flapping. If I had this question in the
> > lab, I think I would argue the point with the proctor.
> >
> > I think the question would only make sense if it was geared to 2 flaps in
> 30
> > seconds or 3 flaps in 30 seconds.
> >
> > More thoughts ?????
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Milenko Markov
> > Sent: 24 October 2005 21:44
> > To: 'simon hart'
> > Cc: ccielab@groupstudy.com
> > Subject: RE: Route Dampening
> >
> >
> > Simon,
> >
> > lets observe "worst case scenario" (?) : 4 flaps "in" first second, and 1
> > flap in last (30').
> >
> > Penalty would be (4x1000/2)+1000=3000...route would not be suppressed ?
> >
> > I *think* that here two more values playes their role (marked with *) :
> >
> > 1. "Half-life-Once the route has been assigned a penalty, the penalty is
> > decreased by half after the half-life period (which is 15 minutes by
> > default). The process of reducing the penalty happens every *5 seconds*."
> >
> > and
> >
> > 2. " Reuse limit-As the penalty for a flapping route decreases and falls
> > below this reuse limit, the route is unsuppressed. That is, the route is
> > added back to the BGP table and once again used for forwarding. The
> default
> > reuse limit is 750. The process of unsuppressing routes occurs at
> > *10-second* increments. Every 10 seconds, the router finds out which
> routes
> > are now unsuppressed and advertises them to the world."
> >
> >
> >
> http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr
> > _c/ipcprt2/1cfbgp.htm#wp1002395
> >
> >
> > more ideas ?
> >
> > regards,
> > Milenko.
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > simon hart
> > Sent: 24. oktobar 2005 22:31
> > To: Charles Cahoon; ccielab@groupstudy.com
> > Subject: RE: Route Dampening
> >
> > Charles,
> >
> > You will get a penalty of 1000 for each flap. Your half-life will default
> > to 30 seconds (best to leave it there).
> >
> > You need to work out what to suppress at
> >
> > If you flapped immediately 5 times in the first couple of seconds you will
> > get a penalty of 5000, however a figure of 5000 does not work in the
> > following scenario:-
> >
> > If you flapped 2 times in the first second = 2000 and then flapped 3 times
> > in the last couple of seconds you will get a penalty of
> >
> > roughly 2000/2 = 1000 + 3000 Therefore you will need a
> suppress-threshold
> > of 4000 or above, but below 5000
> >
> > I would probably go for 4001 - any comments on this figure appreciated.
> >
> > So
> > Half-life = 30
> > Suppress-threshold = 4001
> > Reuse-threshold = Arbitary for this exercise, however I would go with
> Cisco
> > recommendation of suppress-threshold = reuse*2, therefore 2000
> > Max-suppress = leave at default (60)
> >
> > Simon
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Charles Cahoon
> > Sent: 24 October 2005 20:30
> > To: ccielab@groupstudy.com
> > Subject: Route Dampening
> >
> >
> > Looking for a simple explanation,
> >
> > I have read a great deal about how to dampen but it's not getting any
> > clearer
> > for me. I was hoping that someone can help.
> >
> > My question is if I want to remove a route if it flaps 5 times in 30
> > seconds?
> >
> > Using the "Half-Life, Suppress Threshold, Reuse Threshold and Maximum
> > Suppress
> > time" not sure these correlate, what am I missing?
> >
> > Thanks for the help
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> > --
> > No virus found in this incoming message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.344 / Virus Database: 267.12.4/146 - Release Date: 21/10/2005
> >
> > --
> > No virus found in this outgoing message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.344 / Virus Database: 267.12.4/146 - Release Date: 21/10/2005
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> > --
> > No virus found in this incoming message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.344 / Virus Database: 267.12.4/146 - Release Date: 21/10/2005
> >
> > --
> > No virus found in this outgoing message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.344 / Virus Database: 267.12.4/146 - Release Date: 21/10/2005
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
> --
> No virus found in this incoming message.
> Checked by AVG Anti-Virus.
> Version: 7.0.344 / Virus Database: 267.12.4/146 - Release Date: 21/10/2005
>
> --
> No virus found in this outgoing message.
> Checked by AVG Anti-Virus.
> Version: 7.0.344 / Virus Database: 267.12.4/146 - Release Date: 21/10/2005
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sun Nov 06 2005 - 22:00:55 GMT-3