Application-level versus network-level proximity

We motivate in this paper the need for application-level proximity. This proximity is a function of network characteristics that decide on the application performance. Most of existing protocols rely on the network-level proximity as for example the one based on the delay (e.g., the delay closest peer is the best peer to contact). In this paper, we study how much the two proximity definitions differ from each other. The work consists of running extensive measurements over the PlanetLab overlay network and comparing different proximity definitions. Our major observation is that the delay proximity is not always a good predictor of quality and that other network parameters are to be considered as well based on the application requirements, Particulary, the best peer to contact is not always the delay closest one. This can be explained by our other observation, that of the slight correlation of network characteristics with each other.