(Also crossposted from freenet-dev into p2p-hackers.) On Tue, 27 Feb 2001, Theodore Hong wrote:
> Peter Todd <retep at penguinpowered.com> wrote: < > > > Alpine is horribly inefficient. Being a all-to-all network topology > > where every search request is sent to *every* machine on the network > > it's bandwidth useage for any single node is n where n is the number > > of nodes in the network. Therefore the bandwidth usage for all of > > nodes is n^2, obviously horribly inefficient. > > Well, that's the point -- they claim they can do it: "The low overhead of a > DTCP connection means hundreds of thousands of concurrent connections can > be used by an application for direct communication with a large number of > peers." Can that be true? If capacity grows with n and the amount of messages with n^2, the it is easy enough to figure out how many nodes can be supported. If you want to support 1000 nodes, the amount of capacity added by each node must be 1000 times greater than the amount of messages generated by each node (per unit time) times the size of the message. If search messages are only 1 kB or so, and nodes in the network generate an average of 10 new searches per hour, then each node must make 10,000 kB of transfer capacity available per hour to handle that traffic. That is a comfortable background level for people with broadband connections (if not for the ISPs serving them). Continuing up, at 46,000 nodes you are saturating a 1 megabit connection - which would indicate (given that my numbers of 1 kB and 10 searches per hour were probably conservative) that the Alpine people are sprouting turkey excrement. If you turn it the other way of course - even if your search horizon contains only 1000 people, that is certainly enough for many uses of P2P (including filesharing). I think that if the people working on Gnutella clones would just get there acts together, do the math, and code their systems with recognition that the network cannot scale, but that the horizon can still be large enough to satisfy most users, we would have viable decentralized Napster alternative today... > > theo > > > _______________________________________________ > Devl mailing list > Devl at freenetproject.org > http://www.uprizer.com/mailman/listinfo/devl > _______________________________________________ Devl mailing list Devl at freenetproject.org http://www.uprizer.com/mailman/listinfo/devl
