Re: [Sipping] FW:WGLC Review: draft-ietf-sipping-presence-scaling-requirements-01.txt

[Paul Kyzivat <[e-mail]>]

Christian,

Certainly DoS attacks need to be addressed in practice.
But I question whether they need to be included in the scaling analysis.
Perhaps it would be sufficient to state that the scaling analysis 
assumes the absence of DoS attacks.

Or, I guess, one could assume that in the kind of large scale 
deployments being considered there will *always* be some sort of DoS 
attack, and try to incorporate the cost of coping with that into the 
analysis. But I can't imagine how the statistical characteristics of 
such an attack could be incorporated.

	Paul

Schmidt, Christian 1. (NSN - DE/Munich) wrote:
> Hi Paul,
> 
> Sorry for the late reply, but the harddisk of my notebook has refused
> further service this week.
> 
> I like your new version of REQ-007, it covers the point I raises.
> 
> A related question: What about Denial of Service attacks? Should we
> provide requirements, to restrict the risk of DoS attacks? For example
> to restrict the number of watchers per presentity or to restrict the
> number of changes in presence status per time-unit?
> 
> Regards
> Christian 
> 
> 
> 
>  
> 
> -----Original Message-----
> From: ext Paul Kyzivat [mailto:[e-mail]] 
> Sent: Freitag, 19. September 2008 15:31
> To: Schmidt, Christian 1. (NSN - DE/Munich)
> Cc: ext Gonzalo Camarillo; [e-mail];
> [e-mail]; Mary
> Barnes
> Subject: Re: [Sipping] FW:WGLC Review:
> draft-ietf-sipping-presence-scaling-requirements-01.txt
> 
> 
> 
> Schmidt, Christian 1. (NSN - DE/Munich) wrote:
>> Hi,
>>
>> A short comment / queston, concerning a scalility requirement:
>>
>>    o  REQ-007: Presence systems (intra or inter-domain) SHOULD scale
> in
>>       linear proportion to the number of watchers and presentities in
>>       the system.
>>
>> This requirement takes not into account the relationsship between
> presentities
>> And watchers. Meaning for example in adding few presentities with a
> huge amount of watchers,
>> This linear proportion can not be achieved. Therefore I think, this
> has to
>> Be taken into account in this requirement.
> 
>>    o  REQ-007: Presence systems (intra or inter-domain) SHOULD scale
> in
>>       linear proportion to the number of watchers and presentities in
>>       the system. Precondition ist that the number of watchers of a
> presentity and the
>>       number of precentities a watcher can monitor is restricted.
> 
> How about:
> 
>     o  REQ-007: Presence systems (intra or inter-domain) SHOULD scale in
>        linear proportion to the number of watchers and presentities in
>        the system, so long as the average number of watchers per
>        presentity has a fixed bound.
> 
> Namely, its not necessary to bound any particular user's behavior so 
> long as the average is fixed rather than proportional to the number of 
> presentities.
> 
> Over the short term that is likely to be true by accident. Over longer 
> periods of time, as the system becomes ubiquitous, the average number is
> 
> likely to rise but maybe not in proportion to the number of users in the
> 
> system.
> 
> This behavior could probably be constrained if there was a cost to the 
> end user associated with having a buddy.
> 
> 	Thanks,
> 	Paul
> 
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