1063, Morse Ave, Apt 9-111, Sunnyvale CA 94089. Phone: (518)-257-0027. E-mail: Web site:

Current Visa Status: H-1b

Doctor of Philosophy (Ph.D) (Computer Systems) Graduating in March 2008, Rensselaer Polytechnic Institute, Troy, NY. Advisor: Prof. Shiv Kalyanaraman Master of Science (M.S.) (Computer Science) December 2002, Arizona State University, Tempe, AZ. Bachelor of Engineering (B.E.) (Computer Engineering) June 2000, University of Bombay, India.

Publications /Patents
For a list of publications, patents and talks please see

 July 2009- current : Software Engineer - Currently employed at Cisco Systems in the Advanced Architecture and Research group as a researcher and engineer. - Worked on setting up the Cisco cloud computing lab and researched emerging cloud issues such as storage, services and networking on clouds. Worked extensively with Eucalyptus, Rocks, Xen and Vmware. - Developed a TCP variant called BLAST designed for high bandwidth-delay product networks and designed for tolerating packet losses. Patent filed. - Worked on developing a video architecture for bandwidth sharing using network feedback. Patent filed. Summer Intern Summer (2005, 2006, 2007) - Continued my doctoral research at AT&T- Labs (Research) in the Networking group with my thesis committee member Dr. K.K.Ramakrishnan. The research work involved studying the interactions of LT-TCP with link-layer mechanisms. Apart from the development of LT-TCP, I also developed a linklayer protocol (LL-HARQ) that can work well under high loss and disruption conditions. This work led to publications in conferences/workshops and was also presented at IETF 69 in Chicago. Graduate Teaching/ Research Assistant Spring 2001- Fall 2004 - Administered the course Embedded Control at RPI for 280 students. This included developing material, setting exams and assignments, managing 20+ Teaching Assistants and maintaining the lab. URL: - Graduate and undergraduate courses in networking and programming courses. - Assembly language programming (Intel microprocessors) course. - Research Assistant (Summer 2004, Spring 2006, Fall 2007 - current) Project Trainee – V.S.N.L. (Govt. of India enterprise). Aug 1999 - May 2000 - Created a web-based application „Traffic (Data) Information Management System’ for creating reports from an Oracle database using Java Servlets, HTML, Java Web Server, JDBC-ODBC Bridge, Advanced SQL and Session Tracking. Languages: Java, C++, C and Assembly Language (Intel x86 and Motorola HC6800 and HC6811), Tcl, Perl, Awk and various scripting languages. Platforms: Red Hat Linux, Unix (Solaris, HP), Mac OS, VMS/VAX and Windows 2000/NT.




 

    

Embedded Systems: VxWorks on Intel IXP-1200 based platform, Linux on Accelent IDP (SA-1100 processor) and SiLabs C8051F020 Microcontroller. Kernel skills: Familiar with Linux and OpenBSD/Freebsd kernel programming in the area of networking and drivers. Simulators: Highly proficient with Network Simulator (ns-2)., basic knowledge of OPNET. Wireless Drivers: Experience with Atheros-based chipset/ Madwifi driver hacking (net80211 stack). Other skills/ interests: Unix/Linux administration (maintained the Networks Lab in ECSE,RPI), Unix/Linux Kernel internals, Network Programming

 Current Research Work (Ph.D.) My thesis work involves understanding the performance of current state-of-the art transport and link protocols under high and severe loss conditions. The work identified performance problems of protocols such as TCP-SACK (current state-of-the-art). I showed how TCP-SACK collapses beyond an error rate of 5% and then designed a transport protocol called Loss-Tolerant TCP (LT-TCP) with significant performance improvements under a wide range of loss conditions (up to 50% average loss rate) with scalable overheads which implies that no penalty is paid under benign conditions. To complement this transport protocol in terms of functionality, I designed a link protocol called Link-Level(LL)-HARQ that delivers high goodput, low link latency and low loss rates even under high loss conditions. As users start expecting high application data rates with low latency in emerging wireless networks, I expect our contributions to be of value where wireless links play a large role in the end-end path in networks. More details can be found at - Loss-Tolerant TCP: Research involves augmenting TCP with reliability and congestion response enhancements that will enable TCP to perform well in wireless scenarios. Reliability is provided by adding a layer of Forward Error Correction (FEC) to TCP both in a reactive and proactive manner. TCP‟s congestion response is changed by adapting the segment size dynamically. The objective is to build a complete scheme to enable TCP to operate well in multi-hop error-prone wireless scenarios. - Robust Link-Level Hybrid FEC/ARQ: To complement LTTCP at the transport layer, similar mechanisms are added to the link-level to make it robust and resilient under extreme and high erasure regimes. The mechanisms are designed to provide a low residual error rate under the constraints of inorder delivery and low latency while being robust. Combined with LT-TCP, these mechanisms provide a robust solution for operating under paths exposed to high erasure conditions. It is capable of operating under not only high loss and bursty error conditions but also under conditions of outage. - Measurements and Traces: The LT-TCP protocol was tested with real-world data traces collected from airborne networks by our collaborators at MIT-Lincoln Labs and benefits over TCP-SACK were verified. We are also currently generating traces of wireless performance on the ORBIT wireless testbed. This involved modifying the Madwifi driver for Atheros chipsets under Linux (net80211 wireless stack) to run extensive experiments on the ORBIT wireless testbed. -Internet Engineering Task Force (IETF) Contributions: As a part of my doctoral research, I have contributed to the discussions in the standards body IETF in the Internet Congestion Control Research Group (ICCRG) working group. My presentation to ICCRG at IETF 69 (Chicago) is available at Based on the positive feedback, I am tuning LT-TCP to ensure backwards compatibility with current Internet protocols. I am also implementing the LT-TCP protocol in OpenBSD 4.1. to serve as a reference implementation. --Extension of LT-TCP to multiple-paths: The Loss-Tolerant TCP (LT-TCP) which I designed was extended by our research group to exploit diversity benefits offered by multiple (error-prone) paths between the sender and destination. Multi-Path Loss Tolerant TCP (MPLOT TCP) is designed to overcome not only high loss rates but also exploit path diversity to give superior performance even under highly lossy conditions by moving congestion-control to a per-path basis while providing reliability on a per-connection (over all paths) basis.


Research work (M.S.) Research involved improving TCP efficiency in ad hoc mobile networks and sensor networks. The idea was to recognize limitations of TCP in multi-hop wireless environment and make changes to improve throughput and performance in an ad hoc setting. Implementation involved modifying DSR protocol used for ad hoc networks to improve TCP performance. The improvements were simulated on the ns-2 simulator. M.S. thesis is available at

Other Projects Community Wireless Networks: Project funded by Intel Corp. with the aim of providing broadband access to users using a wireless infrastructure meshed network. The idea is to implement an infrastructure of low-cost routing devices in a mesh structure that will provide homes in a community with high-speed broadband access. My contribution was in setting up and administering the wireless nodes/antennas in the wireless testbed deployed at RPI. Co-operative Networks: In this project, I helped in designing a cross-layer optimization scheme between the MAC and networking layers. The idea is to use antenna diversity in the MAC layer in combination with clustering based routing algorithms to obtain synergistic benefits. The relevant publication is available at Multicasting in Wireless Environment: Research involved analyzing and simulating a hierarchical caching model in a wireless environment. This model was selected out of various models from literature and simulated in C++. Project involved modifying the existing caching model to optimize it for mobile networks by taking into account user mobility characteristics. Selective Denial of Service: - S-DoS is a subtle variation of Denial of Service (DoS) attacks and are relatively much more difficult to detect. Denial is of certain services to certain users at certain times. - Project also involved building a prototype for a tool that helps in detection of “denial of service” (DoS) attacks over the Internet. Detection Tool has been developed into a web-based application that helps monitor traffic on a web site. Embedded Systems: - Experience with Vxworks Real-Time OS.I wrote a Joystick driver under Vxworks for a Gravis Destroyer analogue joystick to read joystick positions. Course included other experiments with concepts like scheduling, booting and process admissibility on an IXP-1200 Strong Arm processor. - Embedded Linux on Accelent IDP board with Strong Arm 1110 processor. Studied several aspects of embedded Linux systems including network drivers, parallel ports and scheduling. Modified the kernel slightly to experiment with parallel ports. Unix-based Projects: - Lock Server Implementation: Implemented a centralized lock server responsible for queuing lock requests from clients and granting locks on availability of resources. - Load sharing system (process migration): Implemented a distributed system wherein four servers receive a continuous stream of processes which are migrated to another server that is relatively less loaded where the process is completed. Java-based projects: - Have completed several projects in Java. These include an online game, a chat server and client /application using RMI and JMS and others. Have experience with Java Web Server, Apache and Tomcat web servers. Affiliations / Professional contributions - Peer-reviewed numerous papers for various journals, conferences and workshops.

- Contributed to IETF discussions. - IEEE Student Member References Prof. Shivkumar Kalyanaraman: Professor in Dept. of ECSE, Rensselaer Polytechnic Institute. Address: JEC 6042, 8th street, Troy, NY 12180. Email: Ph: 518-276-8979 Web site: Dr K.K. Ramakrishnan: IEEE Fellow and AT&T Fellow at AT&T Labs (Research). Address: 180 Park Ave, Bldg 103, Florham Park, NJ 07932 Email: Ph: 973-360-8764 Web site: Prof. Koushik Kar: Asst. Professor in Dept. of ECSE, Rensselaer Polytechnic Institute. Address: JEC 6048, 8th street, Troy, NY 12180. Email: Ph: 518-276-2653 Web site:

To top