[p2p-hackers] what really happened to Skype?

[André Panisson]

Hello Folks,
That's my contribution, it's only an hypothesis, but think about this:
Let's say that a researcher brings to a company the theory that all 
computers in the Internet have an average uptime of 'x', and that 75% of 
the computers have uptime of y=x/2. Let's say that this proposition has 
been proved by many studies and researches. Let's say that the system 
uses a DHT where 75% of the network are supernodes. So, the software 
architect find the 'y' value and fixes it as a parameter in the 
software, and all computers with more than 'y' of uptime are supernodes.
Let's suppose now that something new happened in the network, something 
that invalidates the above theory, and that reduces drastically the 
value of 'y'. The immediate results of this change are:
1. The number of nodes in the DHT are not enough to perform the needed work;
2. Without a software patch, the system will be stable again only when a 
good number of nodes have an uptime of 'y' or more
3. The architect that fixed the 'y' value in the software is fired;
4. The researcher that proved the above theory is fired;
5. A new patch with corrections is released.
The theory could be different, as I don't know de theory, but the lesson 
is the same: in a dynamic ambient as the Internet, some theories valid 
and very well proved yesterday can be invalidated tomorrow :)
- Panisson

David Barrett wrote:

>Reading the Skype blog post, it doesn't sound like the problem was due to
>lack of central resources, but rather some catastrophic bug in the P2P
>network itself -- like it was unable to reform the DHT (or whatever) in the
>wake of a massive churn event.
>
>I mean, it shouldn't take *2 days* to log in 9 million users, and unless
>this was coupled with servers actually suffering hardware malfunction (of
>which there's no indication), I can't see any reason why it'd take that long
>to simply deal with a big backlog of authentication requests.
>
>Does anyone know much about the Skype P2P/DHT/network algorithm, and can
>they hypothesize what sort of event could cause it to take so long to get
>back into operation?
>
>Also, was Skype 100% down for 2 days followed by it coming 100% back up
>(indicative of a central server problem), or was it suffering from varying
>levels of failure throughout that took a couple days to clear up (suggesting
>P2P network problems)?
>
>-david
>
>  
>
>>-----Original Message-----
>>From: p2p-hackers-bounces at lists.zooko.com [mailto:p2p-hackers-
>>bounces at lists.zooko.com] On Behalf Of Alen Peacock
>>Sent: Monday, August 20, 2007 1:39 PM
>>To: theory and practice of decentralized computer networks
>>Subject: Re: [p2p-hackers] what really happened to Skype?
>>
>>Absolutely true that Skype hasn't given us enough details to figure
>>out exactly what happened or why, but that doesn't prevent the looser
>>cannons among us from taking a shot:
>>http://flud.org/blog/2007/08/20/p2ps-skype-induced-blackeye-or-why-
>>diversity-is-good/
>>
>>Alen
>>
>>
>>On 8/20/07, zooko <zooko at zooko.com> wrote:
>>    
>>
>>>Folks:
>>>
>>>This is a fascinating case study, but we don't yet have enough
>>>information to really learn from it!
>>>
>>>http://heartbeat.skype.com/2007/08/what_happened_on_august_16.html
>>>      
>>>
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>>    
>>
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>  
>