Rice Networks Group Research Project Archive

Rice Packet Ring

End-to-end performance bottlenecks are increasingly encountered at the network edges. In metropolitan backbones, such networks are most often configured as rings due to their fault tolerance properties. While widely studied through the 1980's in the context of token protocols, circuit switching, and fault tolerance, today's packet rings are formed via point-to-point packet-based duplex connections of Gigabit Ethernet or protocols such as Resilient Packet Ring (IEEE 802.17). Our goal in this project is to devise distributed ring scheduling algorithms which are able to ensure a traffic class (perhaps with multiple access points) fair and/or guaranteed rate access throughout the ring. We have devised a new protocol termed DVSR and developed a 1 Gb/sec network processor prototype and testbed implementation.

Denali: Scalable Services for the Internet

Realizing new services on the Internet requires edge-based solutions for both deployability and scalability. In this domain, we are exploring (1) QoS management. We are studying the effectiveness of real-time flow aggregation and edge-based admission control to simultaneously achieve high utilization and scalability. We have developed a simple model of aggregation to show that it is an effective replacement to per-flow reservations provided that the time scale of demand variation and the time scale of signaling are separated by at least two orders of magnitude. Moreover, we have shown that end-point admission control via host probing also represents a compelling alternative to IntServ. (2) Bandwidth inference and traffic control. We are developing new techniques to infer a network or system's available bandwidth from the endpoints, with applications to both QoS control and performance optimization.

Wide Area Redirection of Dynamic Content

Traditional approaches to mirroring, caching, and content distribution have an underlying assumption that minimizing network hop count minimizes client latency. However, with uncongested backbones and potentially high-latency service times for dynamic content, such techniques are of limited effectiveness. In this work, we are developing an architecture in which dispatchers at an overloaded Internet Data Center (IDC) redirect requests for dynamic content to a geographically remote but less loaded IDC. We show with both analytical modeling as well as testbed experiments that the delay savings of redirecting requests to a lightly loaded IDC can far outweigh the overhead in inter-IDC network latency. Consequently, client end-to-end delays are significantly reduced without requiring modifications to clients, servers, or DNS.