On Fri, Mar 14, 2008 at 3:46 PM, Henning Schulzrinne <[EMAIL PROTECTED]> wrote: > There are many different ways to identify services and to identify > candidates. However, since the DHT structure generally has no > relationship to network or geographic topology, I don't see how this > relates to finding a (topologically) nearby server. >
We did some experiments using network position determined by a peer's ICS (internet coordinate system) coordinates, specifically using the Vivaldi algorithm. The relay determines its coordinates and indexes its service advertisement in the DHT using a key which includes its coordinates aligned to a grid. We tested this on three internet topology data sets with 1500+ nodes and also tested for coordinate stability given some churn. The benefit of the DHT is that it scales nicely for large overlays with large numbers of relay candidates to chose from. Also the key distribution is fairly uniform. Since existing ICSes are known to be innaccurate we ended up with a hybrid scheme that combines coordinate-based discovery followed by some probing. Details are in: J. Buford, A. Wang, X. Hei, Y. Liu, K. Ross. Discovery of In-Band Streaming Services in Peer-to-Peer Overlays. IEEE Globecom 2007, Nov. 2007. Here's the pdf of the paper: http://www.samrg.org/p2psip/RelayDiscovery-Globecom07-PID474604.pdf We also tested using the DHT to do location-based discovery using keys based on geographic position, which is potentially useful in location-based service discovery, but not relevant to relay selection. Again, scalable and good key distribution properties in the DHT. See: J. Buford, A. Brown, M. Kolberg. Meta Service Discovery. IEEE 3rd International Workshop on Mobile Peer-to-Peer Computing (MP2P) 2006, March 2006. John > > On Mar 14, 2008, at 11:39 AM, Victor Pascual Ávila wrote: > > > On Fri, Mar 14, 2008 at 4:28 PM, John Buford <[EMAIL PROTECTED]> wrote: > >> no modification to the DHT or overlay protocol was needed to > >> support these cases. as long as you can describe a service > >> with a key that all participating peers understand, the DHT should > >> work for service lookup. > > > > If I understand it correctly, do all peers need to know a Service-ID > > (exact matching search) to discover its associated service provider? > > What happens if a peer wants to publish a new (non-well-known) service > > into the overlay? > > > > Thank you, > > -- > > Victor Pascual Ávila > > _______________________________________________ P2PSIP mailing list [email protected] https://www.ietf.org/mailman/listinfo/p2psip
