Zafar Ayyub Qazi's Homepage
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Zafar Ayyub Qazi

Ph.D Candidate
Computer Science Department
Stony Brook University
NY, 11794

Email: zaqazi [at] cs [dot] sunysb [dot] edu

Here is my CV

Home | Ph.D. Log | Research | Publications | Teaching | Miscellaneous

I am a Ph.D. candidate in Stony Brook University. I am advised by Prof. Samir Das and Prof. Vyas Sekar (Carnegie Mellon University). My broad research interests are in computer networks and distributed systems. My research spans data centers, software-defined networking, middleboxes, virtualization, and mobile/wireless networking.

Ph.D. Log

  • 10/15: Submitted my paper on cellular core redesign to SOSR'16.
  • 10/15: Will be attending HotNets'15 in Philadelphia in November. Looking forward to hearing about some exciting ideas.
  • 10/15: Started my blog "My PhD Journey". Will be reflecting over my experiences in the last few years. Check it out [here].
  • 10/15: Finalized my thesis committee. Will be defending my Ph.D. thesis at the end of this year -:).
  • 07/15: Attended NeTS Early Career Workshop. Interesting talks by speakers, you can find some slides [here].
  • 11/14: Attended the AT&T SDN summit.
  • 08/14: Fascinated by Nassim Taleb's new book [Antifragile]. Contemplating "how do we design anti-fragile computer networks?".
  • 08/14: Finished my internship at AT&T research. It was a fun and learning experience.

  • Research

      Simplifying Middlebox Policy Enforcement using SDN [SIGCOMM'13]


      Networks today rely on middleboxes (e.g., firewalls, VPN gateways, proxies, intrusion detection and prevention systems, WAN optimizers) to provide critical performance, security, and policy compliance capabilities. Achieving the performance and security benefits that middleboxes offer, however, is highly complex. In this project, we addressed algorithmic and system design challenges to demonstrate the feasibility of using SDN to simplify middlebox management. We propose SIMPLE, an orchestration layer for managing middleboxes using SDN. It ensures middlebox-specific policy enforcement and improves middlebox loading balancing by 6X compared to today's deployments.

      Zafar Ayyub Qazi, Cheng-chun Tu, Luis Chiang, Rui Miao, Vyas Sekar, Minlan Yu. SIMPLE-fying Middlebox Policy Enforcement Using SDN. ACM SIGCOMM 2013 [PDF] [Slides].

      Designing a Minimally Disruptive Elastic Cellular Core [Under Submission]


      Today's cellular core, which connects the radio access network to the Internet, relies on fixed hardware appliances placed at a few dedicated locations and use relatively static routing policies. As such, today's core design has key limitations---it induces inefficient provisioning tradeoffs and is poorly equipped to handle overload, failure scenarios, and diverse application requirements. To address these limitations, we propose KLEIN, a design that stays within the confines of current cellular standards and addresses the above limitations by combining network function virtualization with smart resource management. We address key challenges w.r.t. scalability and responsiveness and in realizing KLEIN via backwards-compatible orchestration mechanisms. We show that KLEIN can scale to billion of devices and is close to optimal for wide variety of traffic and deployment parameters.

      Zafar Ayyub Qazi , Phani Krishna, Vyas Sekar, Vijay Gopalakrishnan, Kaustubh Joshi, Samir Das. KLEIN: A Minimally Disruptive Design for an Elastic Cellular Core. [Under Submission]

      All-Wireless Inter-Rack Data Center Design Using FSOs [SIGCOMM'14]


      Designing data centers (DC) is hard. A robust data center network must satisfy several goals: high throughput, low equipment and management cost, robustness to dynamic traffic patterns, incremental expandability, low cabling complexity, and low power and cooling costs. We explored the vision of a flexible, all-wireless, inter-rack datacenter (DC) fabric. Towards this end, we proposed FireFly, which is a flexible, all-wireless, inter-rack datacenter fabric that uses free-space optics and achieves performance close to a full bisection bandwidth network but at only 40-60% of the cost.

      Navid Hamed Azimi, Zafar Ayyub Qazi, Himanshu Gupta, Vyas Sekar, Samir Das, Himanshu Shah, Ashish Tanwer. FireFly: A Reconfigurable Wireless Datacenter Fabric, using Free-Space Optics. ACM SIGCOMM 2014. [PDF] [Slides]

      Application Awareness in Software Defined Networks [SIGCOMM'13]


      Software-Defined Networking (SDN) is capable of L2/3/4-based policy enforcement but agnostic to higher layers. Designed Atlas, a system that enables accurate and scalable application classification in SDN. It employs a machine learning (ML) based traffic classification technique, a crowd-sourcing approach to obtain ground truth data and leverages SDN's data reporting mechanism and centralized control. Atlas achieved 94% accuracy for top 40 Android applications on HP Labs wireless networks.

      Zafar Ayyub Qazi, Jeongkeun Lee, Gowtham Bellala, Tao Jin, Manfred Arndt. Application-Awareness in SDN. ACM SIGCOMM (poster/demo session) 2013. [PDF] [Poster]

      Multi-Radio Multi-Vehicle System for Vehicular WiFi Access [VANET'13]


      One of the most vexing problems for vehicular WiFi access is intermittent connectivity. In this project, we address the problems of handoff latencies and coverage holes by using a Multi-Radio-Multi-Vehicle (MRMV) system. In the MRMV system, each vehicular client can associate with multiple road-side APs simultaneously thus masking handoff latencies. Also, when a client finds itself in a coverage hole, it can treat other vehicular clients in the vicinity as relays for its data and communicate with them over a relay link. Evaluation on a real metro-scale network showed that MRMV can substantially reduce coverage holes .

      Pralhad Deshpande, Zafar Ayyub Qazi, Samir Das. MRMV: Design and Evaluation of a Multi-Radio Multi-Vehicle System for Metro-WiFi Access. ACM VANET (MobiSys workshop) 2013. [PDF] [Slides]



    Teaching Assistant, Stony Brook University (Spring 2010 and Fall 2010)
    • CSE 150 : Foundations of Computer Science: Honors
    • CSE 160 : Computer Science A: Honors
    • CSE 260 : Computer Science B: Honors
    • CSE 350 : Theory of Computation
    Teaching Assistant, LUMS (Winter 2007)


  • My brother is also a computer scientist. He is a Professor in LUMS, Lahore, Pakistan. He does really cool research and has been a great mentor to me and many other students in Pakistan. Check out his webpage [here]
  • Excellent [advice] I received from my brother when I was starting my Ph.D. Also check out this excellent [advice] by my undergraduate mentor Nabil Mustafa on what it takes to succeed in graduate school.
  • My blog [here]
  • I love playing the piano. Recently I fell in love with Arvo Part's music. Check out [this] beautiful composition by him.
  • I love playing and watching cricket. If you are new to cricket, check out [this].