Zafar Ayyub Qazi's Homepage
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Zafar Ayyub Qazi

Assistant Professor at LUMS

Email: zafar.qazi [at] lums [dot] edu

Here is my CV

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About Me

I am an Assistant Professor in the Computer Science Department at LUMS. My research interests are in computer networks and distributed systems. My research spans cellular networks, mobile/wireless networking and data center networking. Formerly, I was a Postdoctoral scholar in the EECS Department at UC Berkeley. Before that, I earned my PhD at State University of New York, Stony Brook.

Updates

  • 09/20: Our work on mobile Web browsing under memory pressure has been accepted to appear in ACM SIGCOMM CCR, October 2020
  • 05/20: Delighted to share that our work on a new control plane for cellular networks has been accepted in ACM SIGCOMM 2020. Congratulations to Neutrino team at LUMS!
  • 01/20: Our work deconstructing Google's Web Light Service to appear in WWW 2020.
  • 06/19: Our works on (1) a faster cellular control plane and (2) device-aware video adaptation accepted in ACM SIGCOMM 2019 poster session.
  • 12/18: Invited to serve in the Technical Program Committee of ACM SIGCOMM 2019.
  • 10/18: Our works on (1) understanding mobile web performance and (2) video streaming in developing regions to appear in ACM IMC 2018 poster session.
  • 06/18: Awarded Google Faculty Award for our work on making the web faster for users in developing countries.
  • 01/18: Joined LUMS CS Department as Assistant Professor.
  • 05/17: Our work on a new system architecture for cellular packet core accepted in ACM SIGCOMM 2017.
  • 02/17: Our work on flow scheduling over asymmetric topologies to appear in NSDI 2017 poster session.

    Selected Research

      A Low Latency and Consistent Cellular Control Plane [SIGCOMM'20]

      Neutrino


      5G networks aim to provide ultra-low latency and higher reliability to support emerging and near real-time applications such as augmented and virtual reality, remote surgery, self- driving cars and multi-player online gaming. This imposes new requirements on the design of cellular core networks. A key component of the cellular core is the control plane. Time to complete control plane operations (e.g. mobility handoff, service establishment) directly impacts the delay experienced by end-user applications. In this work, we design Neutrino, a cellular control plane that provides an abstraction of low latency and reliable access to user state. Our testbed evaluations based on real cellular control traffic traces show Neutrino provides an improvement in control procedure completion times by upto 3.1x without failures, and upto 5.6x under control plane failures, over existing cellular core proposals. We also show how these improvements translate into improving end-user application performance; for AR/VR applications and self-driving cars, Neutrino performs 2.5x and 2.8x better, respectively, as compared to existing EPC.

      Mukhtiar Ahmad, Syed Usman Jafri, Azam Ikram, Wasiq Qasmi, Ali Nawazish, Zartash Uzmi, Zafar Ayyub Qazi. A Low Latency and Consistent Cellular Control Plane. ACM SIGCOMM 2020 [PDF]


      A High Performance Packet Core for Next Generation Cellular Networks [SIGCOMM'17]

      PEPC


      Cellular traffic continues to grow rapidly making the scalability of the cellular infrastructure a critical issue. However existing EPC solutions scale poorly, in particular with increasing numbers of devices or signaling traffic. The key reason for this poor scalability is the manner in which EPC functions are decomposed which leads to device state being duplicated across multiple components, which in turn results in frequent interactions between these components. To address these limitations, we proposed PEPC, a new state-driven system architecture in which we slice EPC by user such that state for single user is consolidated in one location and EPC functions are (re)organized for efficient access to this consolidated state. We show that PEPC achieves 3-7X higher throughput than comparable software EPCs implemented in industry and enables efficient state migration and customization of processing pipelines.

      Zafar Ayyub Qazi, Melvin Walls, Aurojit Panda, Vyas Sekar, Sylvia Ratnasamy, Scott Shenker. A High Performance Packet Core for Next Generation Cellular Networks. ACM SIGCOMM 2017 [PDF]


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

      Firefly


      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]


      Simplifying Middlebox Policy Enforcement using SDN [SIGCOMM'13]

      SIMPLE


      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].




    Publications

    • Mobile Web Browsing Under Memory Pressure [PDF]
      Ihsan Ayyub Qazi, Zafar Ayyub Qazi, T. Benson, Ehsan Latif, Abdul Manan, G.Murtaza, Abrar Tariq
      ACM SIGCOMM CCR, October 2020

    • Low Latency and Consistent Cellular Control Plane [PDF]
      Mukhtiar Ahmad, Syed Usman Jafri, Azam Ikram, Wasiq Qasmi, Ali Nawazish, Zartash Uzmi, Zafar Ayyub Qazi
      ACM SIGCOMM 2020

    • Deconstructing Google's Web Light Service [PDF]
      Ammar Tahir, Muhammad Tahir Munir, Shaiq Munir Malik, Zafar Ayyub Qazi, and Ihsan Ayyub Qazi
      WWW 2020

    • Fast EPC: A Low Latency Cellular Control Plane [PDF]
      Mukhtiar Ahmad, Wasiq Qasmi, Syed Usman Jafri, Ridah Naseem, Ali Nawazish, Azam Ikram, Zartash Uzmi, Zafar Ayyub Qazi
      ACM SIGCOMM 2019 (poster)

    • Device-Aware Adaptive Video Streaming [PDF]
      Arsalan Ali Gohar Jumani, Fizza Zafar, Zafar Qazi, Ihsan Ayyub Qazi
      ACM SIGCOMM 2019 (poster)

    • Unraveling Poor Video Streaming Experiences in the Developing World [PDF]
      Arsalan Ali Gohar Jumani, Fizza Zafar, Zafar Qazi, Ihsan Ayyub Qazi
      ACM IMC 2018 (poster)

    • Forward to the Past: Untangling Web Browsing on Low-end Mobile Devices [PDF]
      Ihsan Ayyub Qazi, Zafar Qazi, Theophilus Benson, Zaid Ahmed Farooq, Abdul Lateef Haamid, Sohaib Ahmad, Bismah Babar, Syeda Fatima Naqvi
      ACM IMC 2018 (poster)

    • A High Performance Packet Core for Next Generation Cellular Networks [PDF]
      Zafar Ayyub Qazi, Melvin Walls, Aurojit Panda, Vyas Sekar, Sylvia Ratnasamy, Scott Shenker
      ACM SIGCOMM 2017

    • DRIBS: Flow Scheduling over Asymmetric Datacenter Topologies [PDF]
      Tooba Ahsen, Fatima Tariq, Muhammad Tirmazi, Ifrah Idrees, Zafar Ayyub Qazi, Ihsan Ayyub Qazi, Zartash Afzal Uzmi
      USENIX NSDI (poster/demo session)

    • The View from the Other Side: Understanding Mobile Phone Characteristics in the Developing World [PDF]
      Sohaib Ahmad, Abdul Lateef Haamid, Zhenyu Zhou, Zafar Ayyub Qazi, Theophilus Benson, Ihsan Ayyub Qazi
      ACM IMC 2016

    • KLEIN: A Minimally Disruptive Design for an Elastic Cellular Core [PDF]
      Zafar Ayyub Qazi , Phani Krishna, Vyas Sekar, Vijay Gopalakrishnan, Kaustubh Joshi, Samir Das
      ACM SOSR 2016

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

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

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

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

    • Practical and incremental convergence between SDN and middleboxes [PDF] [Slides]
      Zafar Ayyub Qazi, Cheng-chun Tu, Luis Chiang, Rui Miao, Vyas Sekar, Minlan Yu
      Open Network Summit (Research Track) 2013


    Teaching

    Assistant Professor, LUMS
    • CS 582 : Distributed Systems (Fall 2020)
    • CS 382 : Network-Centric Computing (Spring 2020)
    • CS 678 : Topics in Internet Research (Spring 2020)
    • CS 6312 : Privacy in Digital Age (Fall 2019)
    • CS 582 : Distributed Systems (Fall 2019)
    • CS 678 : Topics in Internet Research (Spring 2019)
    • CS 582 : Distributed Systems (Fall 2018)
    • CS 4713 : Introduction to the Internet: Architecture and Protocols (Fall 2018)
    • CS 678 : Topics in Internet Research (Spring 2018)

    Services

  • [A collection of advices for junior faculty] by Jean Yang
  • [Advice] I got when I started my Ph.D.
  • On what it takes to succeed in graduate school [advice]