changing the subject, since the previous subject is not relevant for the current discussion.
>>> (Plus everyone needs to hit *some* server to find the bootstrap nodes >>> anyway... keeping them connected to it and not moving anything but >>> keepalive traffic and the occasionally connection setup, as David points >>> out, is cheap) >> >> The problem comes when media must be relayed through a central server. This >> happens when nodes are behind restricted NATs. > > Bootstrapping, authentication, and rendezvous should be centralized, but > I agree other layers -- including relaying -- are best left to peers. > > The point is those p2p layers are far easier to build atop a solid > centralized core than on top of more p2p. Sure. Cost is usually the differentiator but it is probably decreasing. >> Also, I suspect that the >> administrative costs and pains for managing 15-20 servers may overshadow any >> per-month bandwidth costs for connectivity. > > Are you suggesting that it's easier to manage a 10-million node DHT than > 15-20 centralized servers? I think not. > > If you have 15-20 servers, that means you have millions of active users > and you are a massive success -- the centralized costs and > administration headaches are utterly trivial by comparison. Real numbers will be helpful here. I will like to compare the administrative/bw costs of running Skype, GTalk, MSN, and Yahoo messengers. Anyone with insights? > Also, I should clarify -- the 100K users / $100/mo box ratio I tossed > out is a rule of thumb because it's easy to remember and easy to > achieve. With some work you can find cheaper boxes ($50/mo) and get > them to support even more connections 250K seems pretty easy. Even > 1M/box seems achievable. As long as they only do presence. YouTube may not tell the same story. > Never underestimate the power of appropriate centralization, or your > competitors will beat you to the punch years early. Sure. However, there was nothing that prevented MSN or Yahoo, purely centralized solutions, from offering a good IM/VoIP solution. Skype's success is not solely attributable to p2p. However, the economic cost of their entry into VoIP/IM space was lowered by using a p2p solution for NAT traversal. I am not wed to a pure p2p or a pure centralized solution. The solution can be a hybrid one, as Skype has successfully demonstrated. > >> Nodes need to connect to a central server to get their identity signed by a >> central server. This must happen to prevent Sybil attacks. A bootstrap server >> can be co-located with this authentication server. > > That's one thing that's bothered me with a lot of discussions of P2P. > At the end of the day, real-world p2p systems utterly depend on > reliable, realtime access to centralized components. Successful systems > recognize and exploit this. BitTorrent, eMule, Skype are examples of successful distributed systems. They may not be 'purely' distributed, but work reasonably well. > Usability, security, decentralization. Pick any two. For Skype, can we pick all three? :) -salman _______________________________________________ p2p-hackers mailing list [email protected] http://lists.zooko.com/mailman/listinfo/p2p-hackers
