A Fast and Accurate Replica Selection Mechanism Using Explicit Multicast for CDNs

Server replication mechanism is widely used to improve the availability and real-time characteristic of distributed services in Content Delivery Networks (CDNs). When performing delay-sensitive and/or throughput-sensitive distributed applications such as P2P live streaming, a replica selection middleware that provides dependability and timeliness faces an important problem regarding the prevention of timing failures, which may occur either under normal conditions or when the quality of service degrades due to replica failures and transient overload on the server. To address this problem, we designed an explicit multicast based replica probing and selection mechanism that allows a middleware of client sides to choose a set of replicas to service a client based on their response time so as to meet the client's timeliness requirements. Compared to previous works, our simulation results prove that the proposed mechanism achieves better performance in terms of the replica probing and selection latency, connection establishment latency, protocol overhead, selection accuracy, and scalability of replica group under different scenarios. Besides, the deployment complexity of both clients and servers can be reduced.