Load balance algorithms for anycast

Increasingly, replicated anycast servers are being used to deliver network applications and service ever increasing user requests. Therefore, the strategies used to guarantee network bandwidth prerequisites and perform load balancing across the nodes of an anycast group are critical to the performance of online applications. In this paper, we model user requests, network congestion and latency, and server load using a combination of hydro-dynamics and queuing theory to develop an efficient job distribution strategy. Current, anycast research does not explicitly consider the system load of nodes within an anycast groups when distributing requests. Therefore, the performance of a heavily loaded anycast system can quickly become congested and uneven as jobs are routed to closely linked nodes which are already saturated with requests. In comparison, the nodes of further away systems remain relatively unused because of other issues such as network bandwidth and latency during these times. Our system redirects requests from busy systems to the idle, remotely linked nodes, to process requests faster in spite of slower network access. Using an empirical study, we show this technique can improve request performance, and throughput with minimal network probing overhead.<br /

Stable round-robin scheduling algorithms for high-performance input queued switches'

High-performance input-queued switches require highspeed scheduling algorithms while maintaining good performance. Various round-robin scheduling algorithms for Virtual Output Queuing (VOQ) crossbar-based packet switch architectures have been proposed. It has been demonstrated that they can operate at high speed (e.g., OC192), and are relatively simple to implement in hardware. In particular, a group of fully desynchronized round-robin scheduling algorithms, named SRR (static round robin matching), which have been proposed recently, achieve pretty, good delay, performance while easy to implement. The main problem with these arbitration algorithms is that they are not stable under non-uniform traffic. In this paper, based on the concept of both randomized algorithms and SRR, we propose a new scheduling algorithm, termed DRDSRR (derandomized rotating double static round-robin), which is shown to be stable under all Bernoulli i.i.d. admissible traffic and performs better than SRR.. In addition, we also propose a novel pipelining scheme for the hardware implementation of these scheduling algorithms which can achieve one more iteration within each cycle time, and hence better performance, when compared with the pipelining schemes used in conventional designs

Anycast services and its applications

Anycast in next generation Internet Protocol is a hot topic in the research of computer networks. It has promising potentials and also many challenges, such as architecture, routing, Quality-of-Service, anycast in ad hoc networks, application-layer anycast, etc. In this thesis, we tackle some important topics among them. The thesis at first presents an introduction about anycast, followed by the related work. Then, as our major contributions, a number of challenging issues are addressed in the following chapters. We tackled the anycast routing problem by proposing a requirement based probing algorithm at application layer for anycast routing. Compared with the existing periodical based probing routing algorithm, the proposed routing algorithm improves the performance in terms of delay. We addressed the reliable service problem by the design of a twin server model for the anycast servers, providing a transparent and reliable service for all anycast queries. We addressed the load balance problem of anycast servers by proposing new job deviation strategies, to provide a similar Quality-of-Service to all clients of anycast servers. We applied the mesh routing methodology in the anycast routing in ad hoc networking environment, which provides a reliable routing service and uses much less network resources. We combined the anycast protocol and the multicast protocol to provide a bidirectional service, and applied the service to Web-based database applications, achieving a better query efficiency and data synchronization. Finally, we proposed a new Internet based service, minicast, as the combination of the anycast and multicast protocols. Such a service has potential applications in information retrieval, parallel computing, cache queries, etc. We show that the minicast service consumes less network resources while providing the same services. The last chapter of the thesis presents the conclusions and discusses the future work