Structuring topologically aware overlay networks using domain names

Overlay networks are application layer systems which facilitate users in performing distributed functions such as searches over the contents of other users. An important problem in such networks is that the connections among peers are arbitrary, leading in that way to a topology structure, which does not match the underlying physical topology. This topology mismatch leads to large user experienced delays, degraded performance and excessive resource consumption in Wide Area Networks. In this work we propose and evaluate the Distributed Domain Name Order (DDNO) technique, which makes unstructured overlay networks topologically aware. In DDNO, a node devotes half of its connections to nodes that share the same domain-name and the remaining half connections to random nodes. The former connections achieve good performance, because the bulk of the overlay traffic is kept within the same domain, while the latter connections ensure that the topology structure remains connected. Discovery of nodes in the same domain is achieved through on-demand lookup messages, which are guided by local ZoneCaches. Our technique is entirely decentralized making it appropriate for use in Wide Area Networks. Our simulation results, which are based on a real dataset of Internet latencies, indicate that DDNO outperforms other proposed techniques and that it optimizes many desirable properties such as end-to-end delays, connectivity and diameter.