I am starting a thread on the samrg mailing list entitled "Can Managed Overlays Prevent 2-Day Outages Such as Skype's in 2007" to discuss the engineering/econonic issues. Please join if you are interested in such a discussion.
Thanks, John On Wed, Mar 18, 2009 at 3:51 PM, Brian Rosen <[email protected]> wrote: > This sounds like a discussion for which the beer part is an order of > magnitude more important than the BOF part. > > I’m not sure we’re going to get anywhere arguing whether management is a > good or bad thing. > > Can we get back to the discussion about p2psip-diagnostics? > > Brian > > From: [email protected] [mailto:[email protected]] On Behalf > Of > Henry Sinnreich > Sent: Wednesday, March 18, 2009 3:37 PM > To: [email protected] > Cc: P2PSIP WG > Subject: Re: [P2PSIP] Comment on p2psip-diagnostics > > Well, maybe management of overlays works and also maybe it makes economic > sense (for who?). > This would have to be proven however not in papers, but in running systems > as well in market for acceptance. > Too bad the Skype and Bittorrent folks who have proven both do not care to > participate in this debate. > As an engineer, I may be excused for not believing in p2p management, until > I see the measurements and numbers. > > > no one knows what happens if the overlay population exceeds some large > number, say >100M, sinces no overlays have been deployed or simulated at > that size - does it degrade >gracefully or become inoperable > > My Skype panel shows right now 16,659,464 people on line and I believe they > have 400 million subscribers. > Skype works exceedingly well for our daily family a/v sessions, coast to > coast. > Does Skype have network management agreements with all the ISPs their p2p > is > crossing? :-) > > >but depending on user expectations for service quality and willingness to > pay > This alone is worth a good beer BOF. > Let’s plan for one. > > Henry > > > On 3/18/09 11:01 AM, "John Buford" <[email protected]> wrote: > > > 2009/3/16 Henry Sinnreich [email protected] > I fully agree, since some naïve folks out there (including me) think that: > 1. p2p is self organizing – not managed – unless fixing node software is > called management. > 2. p2p works across the Internet and crosses many ISP networks, several > times even for any one ISP. The p2p operator may not even be in friendly > relations with some the ISPs and compete with them. > Henry, > > Current overlays have limitations. Here's a partial list of problems, I > expect others on this list can add more: > > - potentially long delays to respond to and correct from network partitions > - inability to detect and correct load imbalance, such as flash crowd > effect > - inability to detect and respond to DDOS attacks > - inability to enforce different classes of service for different peers > - overlay instability at high churn rates, that might be caused by > increases in the number of mobile peers > - no one knows what happens if the overlay population exceeds some large > number, say 100M, sinces no overlays have been deployed or simulated at > that > size - does it degrade gracefully or become inoperable > While there are some research proposals to address some of these problems > individually, it is safe to say that no single design covers all of them. > > In general as long as there are overlay algorithm performance areas which > can not be automatically detected and corrected by self-organizing > algorithms, then there is a need for management agent(s) to be able to > monitor and intervene. > > Sure this boundary is likely to shift over time as algorithms get better. > And monitoring the overlay can help the development of better algorithms. > > Here's a detailed discussion of the limits of today's P2P systems w.r.t. > self-organization: > B. Biskupski, J. Dowling, and J. Sacha, Properties and mechanisms of > self-organizing MANET and P2P systems, ACM Trans. Auton. Adapt. Syst. 2, 1 > (March 2007), 34 pp. > > Here's a look at how overlay management might work: > > J. Buford, Management of peer-to-peer overlays, International J. of > Internet > Protocol Technology, Special Issue on Management of IP Networks and > Services, Vol. 3, No.1, 2008, 2–12. > > Bottom line, ideally P2P doesn't need to be managed, but depending on user > expectations for service quality and willingness to pay, there could be > deployments with overlay operators who provide this for users by managing > the overlay. > > John > > > >
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