Research On Key Issues In Application Of P2P Techniques Within IPv4-IPv6 Hybrid Network

With the fast development of Internet, the exhaustion problem of IPv4 addresses has become more and more serious, which makes the transition of Internet from IPv4 to IPv6 be more urgent. Whether the next generation of Internet protocol--IPv6 can be successfully deployed globally or not, directly affect the future expansion of the Internet. However, IPv6 global deployment has not proceeded as quickly as its designers expected. IPv6 is not backwards compatible, and so far there is no single best IPv4/IPv6 transition mechanism has been widely deployed or effectively used. Therefore, the usage of IPv6 requires that both clients and servers deploy IPv6. However, most of the current traditional servers don't support IPv6; in addition, because the scale of IPv6 networks, users and contents are still relatively small, which forming a negative network effect, this serious obstructs the development of IPv6 deployment. As a result, if the above problems can not be resolved effectively, the future development of the Internet would be restricted.Based on thoroughly studying Peer-to-Peer (P2P) technology, we found that the P2P could provide a new opportunity to solve the above problems. Thus, this dissertation focuses on P2P-related techniques within the IPv4/IPv6 hybrid network. Our research is beneficial to the IPv6 adoption; therefore, it will boost the IPv6 deployment and development, and make the transition from IPv4 to IPv6 smoothly. The main contents and contributions of this dissertation are as follows:(1) BitTorrent, one of the most popular P2P file sharing systems, has attracted wide attention lately. Many earlier researches have verified that the BitTorrent system could provide excellent download performance. However, current implementations of BitTorrent are oblivious to the underlying Internet topology or ISP link costs, resulting in a large amount of cross-ISP traffic. To address the cross-ISP traffic problem caused by BitTorrent, we propose a tracker-side biased neighbor selection algorithm based on landmark clustering. In this approach, clients generate global proximity-aware information by using landmark clustering, and then the tracker uses this information to maintain all peers in an orderly way and provide a biased subset by tracker-side biased neighbor selection algorithm. The simulation results show that our approach can reduce unnecessary cross-ISP traffic significantly, also make downloads fast.(2) In general, studies on the BitTorrent traffic only consider the single IPv4 network. However, with the exhaustion of IPv4 addresses and the development of IPv6, the Internet is being converted from IPv4-only into IPv4/IPv6 hybrid. Therefore, a novel BitTorrent system for IPv4/IPv6 hybrid network is presented in this dissertation. It can further reduce cross-ISP and the backbone traffic by using tracker-side biased neighbor selection algorithm. In order to verify the performance of the above BitTorrent, we design and implement a BitTorrent simulator, using a special IPv4/IPv6 hybrid network topology based on CERNET and CERNET2. The simulation results show that our approach can effectively transfer BitTorrent traffic from IPv4 network to IPv6 network, and significantly reduce the backbone traffic via tracker-side biased neighbor selection algorithm. Besides, it is adaptive to the change in IPv4 and IPv6 network load.(3) In order to alleviate bandwidth shortages of IPv4 networks caused by P2P applications, a P2P resource sharing mechanism based on Hierarchical Distributed Hash Table (DHT) for IPv4/IPv6 hybrid network is proposed in this dissertation. The IPv4/IPv6 inter-operation involved in of P2P applications is solved since both IPv6-only and IPv4-only nodes can look up and obtain the P2P resources in each other's DHT overlays. The simulation results illustrate that such P2P resource sharing mechanism accords with the properties of IPv4/IPv6 hybrid network and leads to good scalability and load balance.(4) In order to promote the transition to IPv6 smoothly, DHTLayer, a novel IPv4/IPv6 transition mechanism based on DHT, is presented in this dissertation. It can fully support IPv4 and IPv6 inter-operation. DHTLayer employs a DHT overlay to maintain the routing information between IPv4 and IPv6. It decouples path selection from packet delivery. In DHTLayer, the Looking-Up Route Path is responsible for selecting paths, and then Delivering Process takes charge of delivering IP packets along the path selected above. Simulation results show that the idda of our transition mechanism cannot be immediately dismissed.(5) During the above studies, we found that the verification of designed system necessary and complex. Although simulations have been widely used in P2P research, the lack of a consensus on the common platform for P2P simulations puts forward challenges to validating research and reproducing results. Based on our preliminary work on the P2P simulations, we design and implement a general discrete event-driven P2P simulator, which provides some P2P simulation examples for IPv4/IPv6 hybrid network. Moreover, the modular and hierarchical design of simulator can greatly improve the flexibility of simulation. We expect that our simulator can contribute to the research on IPv4/IPv6 hybrid network and P2P.