Career
Jain began his career working at Digital Equipment Corporation in Littleton, Massachusetts, from 1978 to 1994, becoming a Senior Consulting Engineer. During his time at Digital, Jain was also a visiting scholar and honorary lecturer at the Massachusetts Institute of Technology in 1983–84, 1985, and 1987.
In 1994, Jain joined Ohio State University as a professor in the Department of Computer and Information Sciences, where he remained until 2002. He co-founded Nayna Networks, Inc. in San Jose, California, in 2000, and served as its Chief Technology Officer until 2007.
In 2005, Jain joined Washington University in St. Louis as a professor of Computer Science and Engineering. In 2016, he was named the Barbara H. and Jerome R. Cox, Jr. Professor.
Research
Congestion control and the DECbit scheme
Jain has worked on network congestion management. He is a co-inventor of the DECbit scheme, a binary feedback congestion avoidance mechanism that was implemented in DECnet and later influenced standards for OSI, Frame Relay, and ATM networks. The scheme allows network switches to signal impending congestion to end hosts by setting a bit in packet headers, enabling hosts to adjust their transmission rates proactively. The paper describing this work, "Analysis of the Increase and Decrease Algorithms for Congestion Avoidance in Computer Networks," received the ACM SIGCOMM Test of Time Award in 2006.
Jain is the author of The Art of Computer Systems Performance Analysis (John Wiley & Sons, 1991), which became a standard textbook on the subject. The book won the Computer Press Association's "Best Advanced How-to Book, Systems" award in 1991. The book introduced several widely used concepts and metrics, including Jain's fairness index, a quantitative measure for evaluating the fairness of resource allocation in computer systems and networks.
ATM Networks
Jain served as the Editor of the ATM Forum Performance Testing Specification. He was involved in the work that led to the development and adaptation of the explicit forward congestion indication (EFCI) scheme for traffic management in ATM networks.
WiMAX 4G Networks
Between 2006 and 2009, Jain served on the Application Working Group at the WiMAX Forum, which was developing the first 4G standard. He was the editor of the WiMAX Systems Evaluation Methodology document. In 2008, he received the WiMAX Forum Individual Contribution Award.
