Hi, In the draft “Self-tuning DHT for RELOAD” (http://www.ietf.org/id/draft-ietf-p2psip-self-tuning-00.txt), which is nowadays a WG item, we specify how a P2PSIP overlay can adapt to changing operating conditions. The main idea is that each peer collects statistical data about the network and dynamically adjusts its stabilization rate, neighborhood set size, and finger table size based on the analysis of the data. In order to do this, each peer produces an estimate of the current network size, leave rate, and join rate. In the simulations we (the authors of the draft) have run, we have observed that an easy way to improve the accuracy of these estimates is to allow peers to share their estimates. We can imagine at least two ways to do this:
(1) Peers piggyback their estimates in RELOAD messages. (2) Each peer asks a subset or all of the peers in its routing table to return their current estimates. In alternative (1), a new ForwardingOption could be used for instance in messages sent as part of the Chord stabilization routines (e.g., Ping). Every peer forwarding such a request or response could add a new ForwardingOption containing its current estimates to the message. The source node, intermediate nodes, and the destination node would store all estimates carried in the ForwardingOptions structures. When the stabilization timer fires, each peer would calculate the final estimate by taking an average (or median) over the estimates received during the stabilization interval and its own estimate. In alternative (2), when the stabilization timer fires, every peer sends a request (e.g., Probe or Inspect) to all or a subset of the peers in its routing table (e.g., to all fingers), asking them to return their current estimates. This would require extending the Probe/Inspect messages. Again, the average or median of the received estimates and the peer's own estimate would be used to calculate the final estimate. Any opinions on which alternative would be the preferred one? We would like to propose using (1) since it does not add any additional messages to the overlay. Also, if using (1), peers can most likely obtain more shared values and thus be able to produce more accurate estimates than by using (2). However, it might also be interesting to allow both approaches. Cheers, Jouni _______________________________________________ P2PSIP mailing list [email protected] https://www.ietf.org/mailman/listinfo/p2psip
