Current Projects:

Trustworthy Peer-to-Peer Networks:

Peer-to-peer systems are rapidly maturing from being narrowly associated with copyright violations, to a technology that offers tremendous potential to deploy new services over the Internet. In many ways, peer-to-peer systems are beginning to herald a paradigm shift in this decade, in much the same way as HTTP in the 1990's. In this project, we are studying challenges in designing peer-to-peer systems in a safe, secure and robust manner, and considering new issues to Internet management due to the proliferation of peer-to-peer systems.

We are currently working in three areas of peer-to-peer systems design. (i) feasibility of generating DDoS attacks using widely deployed peer-to-peer applications and establishing design principles that could make these systems robust against such vulnerabilities, (ii) design and deployment of a monitoring system for automatic detection of malicious users in peer-to-peer applications; and (iii) enabling data confidentiality in an overlay broadcasting system. More..

Heterogeneity and Incentives for Peer-to-Peer Video Broadcasting

We propose the design of bandwidth-demanding broadcasting applications using overlays in environments characterized by hosts with limited and asymmetric bandwidth, and significant heterogeneity in outgoing bandwidth. Such environments are critical to consider to extend the applicability of overlay multicast to mainstream Internet environments where insufficient bandwidth exists to support all hosts, but have not received adequate attention from the research community. We leverage the multi-tree framework and design heuristics to enable it to consider host contribution and operate in bandwidth-scarce environments. Our extensions seek to simultaneously achieve good utilization of system resources, performance to hosts commensurate to their contributions, and consistent performance. We have implemented the system and conducted an Internet evaluation on PlanetLab using real traces from previous operational deployments of an overlay broadcasting system. More..

Abstractions for Enterprise Network Management

Our focus is on the management of enterprise networks.  Despite their critical importance, and their striking differences and diversity compared to carrier networks, enterprise networks have been largely unexplored by networking researchers. We envision a three-pronged research process that involves:
(i) capturing the goals operators have for their networks, through interactions with operators, and "bottom-up'' studies of actual network designs, (ii) elevating the design patterns we observe into abstractions; and (iii) demonstrating that abstractions can simplify both top-down network design, and validation of network properties.

A distinguishing feature of this research is its "white-box'' methodology to studying network designs. Rather than infer network characteristics with limited support from network operators as is common practice today, we will capitalize on our extensive ties with real network operators, and conduct studies using data such as router configuration files obtained with their support, and iterative interactions with them.

We are currently designing abstractions in two areas that are critically important, and widely prevalent in enterprises. (i) use of virtualization, in particular VLANs, to simplify management goals; and (ii) network evolution through planned maintenance. More..