Ashwin Gumaste

Indian Institute of Technology Bombay, Mumbai, Maharashtra, India

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Publications (130)84.19 Total impact

  • Deval Bhamare · Mohan Krishnamoorthy · Ashwin Gumaste ·
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    ABSTRACT: Carrier Ethernet has rapidly advanced to become an important technology in metro transport. However, the overlapping of control plane and data plane in contemporary Carrier Ethernet (CE) networks leads to complex and unmanageable networks. CE networks that use packet technologies ought to be more manageable, scalable and robust. Recently proposed network architecture, Omnipresent Ethernet (OE) recommends that the control and management plane in CE networks be decoupled from the forwarding and routing plane to overcome the problem mentioned earlier. In view of this, we investigate the possibility of a centralized control plane from OE perspective. A centralized control plane is a networking paradigm that abstracts and centralizes the control information of the network from the underlying distributed data-forwarding infrastructure. In this paper, we have focused on engineering and architectural issues related to the design of a centralized control plane for the networks built on OE Networking paradigm. Furthermore, the problem of control traffic overhead in managed networks is analyzed using an appropriate simulation model. A scheme to divide the network into smaller sub-networks is proposed so that the total control traffic is always below some threshold. An Integer Linear Program (ILP) for the controllers' placement in the partitioned network is presented. The ILP attempts to minimize the total control traffic, the total controllers' implementation cost and the overall response time in the network. Since the ILP solves the problem optimally for networks with a limited number of nodes, a heuristic approach is developed and presented for larger and real-time service-provider networks.
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    ABSTRACT: Segment routing has recently been proposed in the IETF toward making IP/MPLS networks service-oriented while simplifying network operations. Segment routing computes paths at the source node using node identifiers and adjacency identifiers conjoined together to create a source-routed path. We propose a scalable transport paradigm as an enabler toward implementing segment routing in provider networks. We propose omnipresent Ethernet, our modification of carrier Ethernet (which is based on source-routed, binary-routed labels embedded in an Ethernet frame), to implement segment routing. We identify some of the scalability issues of the segment-routing proposal in the context of source-routing overhead. To absolve scalability issues of segment routing, two routing schemes that implement multidomain source-routing techniques are proposed. The hierarchical segment-routing (H-SR) scheme is proposed, which deploys a limited number of special nodes called swap nodes that are capable of label swapping to implement routing. The swap-node placement problem is formulated as an integer linear program to minimize the total routing distance within a network. Three heuristic techniques for swap-node selection based on centrality paradigms are presented. The H-SR scheme is further improved by a proposed multisegment-routing (M-SR) scheme that assumes all nodes in the network to be capable of label swapping. The H-SR and M-SR schemes are shown to significantly enhance the scalability of segment routing. A test-bed is built using carrier Ethernet hardware to support segment routing that validates the implementation of the proposed schemes. A simulation model to evaluate the schemes from a scalability perspective and their associated trade-offs is presented.
    Journal of Optical Communications and Networking 05/2015; 7(5). DOI:10.1364/JOCN.7.000445 · 2.06 Impact Factor
  • Ashish Mathew · Tamal Das · Prasad Gokhale · Ashwin Gumaste ·
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    ABSTRACT: The multi-layer network design problem and the mobile backhaul problem are both interesting from the perspective of choosing the correct technology and protocol as well as choosing the appropriate node architecture to meet a wide variety of overlay traffic demands. Network operators encounter two variants of the multi-layer/backhaul problem: 1) For a given set of uncertain traffic demands, which set of technologies would minimize the network cost? 2) Would these technology choices be invariant to the changing traffic demands? This problem of technology choice can essentially be abstracted to a switching and grooming problem with the added complexity of unknown traffic demands, which at best may be approximated to some known statistical parameters. To solve this complex switching and grooming problem, our goal is to make use of the theory of robust optimization with the assumption of known boundary conditions on traffic. We present a comprehensive optimization model that considers technology choices in terms of protocols, physical layer parameters, link boundary conditions, and transmission layer constraints. Validated by simulations, our model shows the stand-off conditions between various technologies and how a network operator must take proactive steps to be able to meet requirements of the next-generation networks and services. Our main result showcases network design using two technology alternatives [1) Multi-Protocol Label Switching (MPLS) + Optical Transport Network (OTN) + Reconfigurable Optical Add–Drop Multiplexer (ROADM) and 2) Carrier Ethernet (CE) + OTN + ROADM] and the effect of robustness on these choices. A heuristic is used for comparative purposes as well as to exhaustively model the dynamic case of brownfield networks.
    Journal of Optical Communications and Networking 04/2015; 7(4). DOI:10.1364/JOCN.7.000352 · 2.06 Impact Factor
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    ABSTRACT: We demonstrate SDN in a service provider network using adapted Carrier Ethernet Switch Routers developed based on principles of segment routing. SDN based service composition and delivery is showcased and validated.
    Optical Fiber Communication Conference, Los Angeles; 03/2015
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    ABSTRACT: Software Defined Networking (SDN) has brought a paradigmatic shift in the networking industry and has led to significant benefits in the data-center and enterprise network domains. The service provider networks that form the largest segment of networking industry, are now evaluating SDN technologies for adoption. In this paper, we present a SDN framework for service provider networks and report the first field trial of SDN in a tier-1 service provider domain. The proposed SDN framework is built using Carrier Ethernet and augmented with recently proposed Segment Routing paradigm manifested through Software Defined-Carrier Ethernet Switch Routers (SD-CESRs). Carrier Ethernet on account of its distinct, programmable control plane and Segment Routing through its source routing capabilities facilitates SDN implementation. The SD-CESRs are deployed in a tier-1 service provider network in the metropolis of Mumbai. The SDN framework is extended through specific APIs to enhance revenue bearing services portfolio of the service provider and performance results from the field are shown to validate the benefits of SDN adoption.
    Global Communications Conferece (GLOBCOM) 2014, Tx, Austin; 12/2014
  • Sarvesh Bidkar · Saurabh Mehta · Rishiraj Singh · Ashwin Gumaste ·
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    ABSTRACT: The integration of layer-2 carrier-class packet technologies with optical transport network is termed as packet-optical integration and is being deployed by service providers for migration from legacy SONET/SDH systems. We present a state-of-the-art carrier-class switch router that facilitates packet-optical integration, thereby achieving best of both the optical and packet worlds. The premise of this switch router is the use of carrier ethernet technology as a packet enabler for achieving statistical multiplexing at fine granularities, while maintaining rich operations, administration, maintenance, and provisioning features. To this end, we proposed the omnipresent ethernet concept that uses binary routing and source routing to support: 1) layer 2 and layer 3 switching and routing, 2) low latency of the order of 1–5 μs even for layer 3 processing, and 3) low-energy consumption. The omnipresent ethernet framework leads to a software defined networking solution, whereby a centralized controller admits services and configures nodes based on homogenous networking parameters. In this paper, we report a commercial implementation of a packet-optical network demonstrated by our designed, fabricated, developed carrier ethernet switch router (CESR). We discuss the architectural considerations, design, and implementation of both the hardware and the control software. A switch architecture achieving 1-μs port-to-port delay across layers 1, 2, and 2.5 based on an opportunistic principle of virtual output queuing is showcased. The novelty is a scalable 96-Gbps cross connect fabric implemented in a field programmable gate array using a two-stage buffer system. A multistate software defined control plane is also reported. An exact analysis of the switch architecture using a combinatorial G/G/1 model is developed. An energy audit of the CESR is showcased. A test bed in the lab replicating a field deployment is presented. An e- haustive set of test cases are developed to test our designed CESR. Results are shown for latency, throughput, service support, frame-size stability, power, and bit error rate, thus validating our design.
    Journal of Lightwave Technology 09/2014; 32(17):3043-3060. DOI:10.1109/JLT.2014.2336374 · 2.97 Impact Factor
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    ABSTRACT: Carrier Ethernet is rapidly being deployed in the metropolitan and core segments of the transport network. One of the emerging flavors of Carrier Ethernet is the IEEE 802.1Qay PBB-TE or Provider Backbone Bridging—Traffic Engineering standard. PBB-TE relies on the assignment of a network-specific Virtual Local Area Network (VLAN) tag, called the Backbone VLAN ID or BVID that is used in conjunction with a backbone Media Access Control (MAC) address for forwarding. The 12-bit BVID along with 48-bit Backbone MAC address are used to forward an Ethernet frame. The assignment of BVIDs in a network is critical, given that there are only 4094 possible assignments, especially for those paths that are overlapping in the network graph and incident at the same destination. While the only way to scale is to reuse BVIDs, this method can lead to a complication if the same BVID is allocated to an overlapping path. To the best of our knowledge, this is the first instance of isolating this problem of limited BVID availability which rises only due to graphical overlap between services. We formulate and solve this as a constrained optimization problem. We present optimal and heuristic algorithms to solve the BVID problem. The optimal approach solves the 'static' case, while the heuristic can solve both the 'static' and the 'dynamic' cases of the BVID allocation problem. Results show that the developed heuristics perform close to the optimal and can be used in commercial settings for both the static and dynamic cases.
    IEEE Transactions on Network and Service Management 06/2014; 11(2):172-187. DOI:10.1109/TNSM.2014.022614.120358
  • Ashwin Gumaste · Shamim Akhtar ·
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    ABSTRACT: Network operators are currently in the midst of a situation in which there is doubling of bandwidth requirement every two years, although the growth in revenue is nearly flat. In this situation providers must plan their networks to optimize for future growth and take into consideration flat-to-declining operating margins. The OPEX benefits of keeping the data in the lower layers of the network stack can be leveraged to plan future networks. We focus on the impact of evolving standards in the lower layers of the telecommunications stack through the contributions of the IEEE, ITU, and IETF. Specifically, we focus on the WDM, carrier Ethernet, OTN, MPLS, and MPLS-TP set of transport standards. These standards have evolved and are being adapted to meet the requirements of next generation networks and currently being considered in the standard bodies. We show through a simulation study that by adopting the packet-optical integrated standard families, providers would benefit because of CAPEX reduction and thereby enhance margins - benefiting the e-community through better services.
    IEEE Communications Magazine 11/2013; 51(11):105-111. DOI:10.1109/MCOM.2013.6658660 · 4.01 Impact Factor
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    ABSTRACT: Service provider networks are becoming increasingly complex with multi-domain and multi-layer capabilities. Multi-layer optimization has been proposed as a mechanism for planning provider-networks focused on optimizing revenue and reducing capital expenditure. In this paper, we study multi-layer optimization from the perspective of deploying services so as to reduce the capital expenditure in provider-networks. To this end we propose a 3-layer network hierarchical model based on IP, OTN and DWDM technologies. In this paper, we propose an optimization model, a heuristic algorithm and their solution methods. While the optimization model deals with the network planning cases involving static traffic demands, the heuristic algorithm solves the dynamic case. We also develop a simulation model to validate our optimization and heuristic approaches.
    2013 IEEE 38th Conference on Local Computer Networks (LCN 2013); 10/2013
  • Source
    Xiaomin Chen · Admela Jukan · Ashwin Gumaste ·
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    ABSTRACT: The need for optical parallelization is driven by the imminent optical capacity crunch, where the spectral efficiency required in the coming decades will be beyond the Shannon limit. To this end, the emerging high-speed Ethernet services at 100 Gbps, have already standardized options to utilize parallel optics to parallelize interfaces referred to as Multi-lane Distribution (MLD). OFDM-based optical network is a promising transmission option towards the goal of Ethernet parallelization. It can allocate optical resource tailored for a variety of bandwidth requirements and that in a fundamentally parallel fashion with each sub-carrier utilizing a frequency slot at a lower rate than if serial transmission was used. In this paper, we propose a novel parallel transmission framework designed for elastic (OFDM-based) optical networks to support high-speed Ethernet services, in-line with IEEE and ITU-T standards. We formulate an ILP optimization model based on integer linear programming, with consideration of various constraints, including spectrum fragmentation, differential delay and guard-band constraints. We also propose a heuristic algorithm which can be applied when the optimization model becomes intractable. The numerical results show the effectiveness and high suitability of elastic optical networks to support parallel transmission in high-speed Ethernet. To the best of our knowledge, this is the first attempt to investigate the parallel transmission in elastic optical networks to support standardized high-speed Ethernet.
    Journal of Lightwave Technology 06/2013; 32(2). DOI:10.1109/JLT.2013.2291318 · 2.97 Impact Factor
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    ABSTRACT: Virtual Machines (VMs) form the central processing entity in data-centers and are key to facilitating cloud computing environments. To make cloud computing a reality in service provider domains, applicability of VMs to metropolitan networks is important. The technology in the metro domain is progressively moving from circuit switched SONET/SDH to packet based Carrier Ethernet. An interesting question that we seek to answer is how does Carrier Ethernet perform for VM migration in data-center and cloud environments. To this end, we perform an extensive simulation study measuring performance of VM migration over both flavors of Carrier Ethernet - namely PBB-TE and MPLS-TP. Our study concludes in the feasibility of Carrier Ethernet as a transport technology in data-centers and clouds.
    Communications (NCC), 2013 National Conference on; 01/2013
  • A. Gumaste · B.M.K. Bheri · A. Kshirasagar ·
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    ABSTRACT: We propose a framework called Fission that facilitates good scalability in terms of supporting large number of servers as well as a protocol that allows efficient, low-latency communication within the data-center. The Fission concept combines an optical backplane (using UDWDM - ultra dense wavelength division multiplexing based speedup in conjunction with a series of optical buses) to physically scale the data-center. The Fission framework uses an efficient protocol that is a modification of Carrier Ethernet. The working of the Fission architecture from a systems and a protocol perspective are described. Issues such as scalability, protocol working and support for services within the data-center are discussed. A simulation study validates our design for latency and scalability - two critical aspects of data-center design.
    Communications (ICC), 2013 IEEE International Conference on; 01/2013
  • A. Gumaste · B.M.K. Bheri ·
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    ABSTRACT: We have proposed the FISSION (Flexible Interconnection of Scalable Systems Integrated using Optical Networks) architecture for data-centers in [1]. The Fission architecture comprises of the creation of sectors that comprise of server systems and switches are backplane wired up using optical buses. These optical buses deploy ultra-dense wavelength division multiplexing (UDWDM). A modified Carrier Ethernet system provides protocol connectivity within the data-center that scales to support beyond a million servers. We delve into the architectural and protocol aspects of the Fission concept, particularly focusing on its scalability, working, wavelength-assignment and protection issues. The working of the Fission concept is further explained through numerical results achieved through rigorous simulation.
    Optical Network Design and Modeling (ONDM), 2013 17th International Conference on; 01/2013
  • S. Bidkar · S. Mehta · D. Bhamare · N. Bajaj · A. Medhekar · A. Gumaste ·
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    ABSTRACT: Circuit switched systems in the metropolitan and core networks are being steadily replaced by the packet optical integration brought about by the steady advances in Carrier Ethernet, Optical Transport Network (OTN) and Reconfigurable Optical Add-Drop Multiplexer (ROADM). We demonstrate a state-of-the-art Carrier Ethernet Switch Router (CESR) with integrated OTN function as a mechanism to better facilitate packet-optical integration leading to service and layer 2.5 routing support. The design, development of this CESR+OTN platform is described. The test-bed showcases an integrated high-speed optical network configured as an inter-connected ring topology of 16 nodes, multi-degree cross-connects and demonstrates next generation application services used for cloud computing and mobile backhaul. Performance results indicate that the packet optical technology proposed by us and showcased in a live test-bed compare similar to (or in some cases better than) a circuit switched network.
    Computing, Networking and Communications (ICNC), 2013 International Conference on; 01/2013
  • Xiaomin Chen · Admela Jukan · Ashwin Gumaste ·
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    ABSTRACT: In elastic optical networks, the spectrum consecutive and continuous constraints may cause the so-called spectrum fragmentation issue, degrading spectrum utilization, which is especially critical under dynamic traffic scenarios. In this paper, we propose a novel multipath de-fragmentation method which aggregates spectrum fragments instead of reconfiguring existing spectrum paths. We propose an optimization model based on Integer Linear Programming (ILP) and heuristic algorithms and discuss the practical feasibility of the proposed method. We show that multipath routing is an effective de-fragmentation method, as it improves spectral efficiency and reduces blocking under dynamic traffic conditions. We also show that the differential delay issue does not present an obstacle to the application of multipath de-fragmentation in elastic optical networks.
    INFOCOM, 2013 Proceedings IEEE; 01/2013
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    ABSTRACT: A light-trail is a generalization of a lightpath allowing multiple nodes to be able to communicate along the path, leading to all-optical spatial traffic grooming. A light-trail exhibits properties of dynamic bandwidth provisioning, optical multicasting and sub-wavelength grooming, and architecturally is analogous to a shared wavelength optical bus. Arbitration within the bus is conducted by an out-of-band control channel. The bus feature results in a node that has a large pass-through loss, restricting the size of a light-trail to metro environments. Due to this limitation, it is difficult to extend the light-trail concept to regional or core networks. In this paper we exhaustively investigate the concept of multi-hop light-trails (MLTs) - a method to provide multi-hop communication in light-trails, thus enhancing their reach. Node architecture and protocol requirements for creating MLTs are discussed. We then discuss design issues for MLTs in regional area networks through a problem formulation that is solved using convex optimization. The problem formulation takes into consideration issues such as routing MLTs as well as assigning connections (defined as sub-wavelength traffic requests) to MLTs. Two polynomial-time heuristic algorithms for creation of MLTs are presented. One of the algorithms is a static implementation, while the other is a dynamic implementation - with unknown traffic. A detailed delay analysis is also presented that enables computation of end-to-end delay over MLTs using different flow assignment algorithms. A simulation study validates the MLT concept.
    Journal of Optical Communications and Networking 12/2012; 4(12):1046-1061. DOI:10.1364/JOCN.4.001046 · 2.06 Impact Factor
  • Ashwin Gumaste · Prasad Gokhale · Tamal Das · M.K. Purohit · Peeyush Agrawal ·
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    ABSTRACT: The growth of broadband services in India has been a fraction of the otherwise very impressive cellular growth of almost 500 million+ connections in the past decade. We extend our work in [1], in which we defined and analyzed the causes of the stagnation of broadband penetration in India, and propose a comprehensive solution. Specifically, we understand the problem from a business perspective, and then propose a novel techno-economic model that is shown to lead to enhanced broadband penetration. This model is based on a concept that we term global content balancing ¿ showcasing the relationship between content and the proliferation of broadband. We show the working of this model and postulate reasons for its acceptability and success. A simulations study evaluates our solution and compares it to usage-based approaches, showing a return on investment improvement.
    IEEE Communications Magazine 05/2012; 50(5):74-81. DOI:10.1109/MCOM.2012.6194385 · 4.01 Impact Factor
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    ABSTRACT: Next-generation passive optical networks (NG-PONs) promise significant bandwidth increase to end users. Research and standardization efforts are underway to enable enhancements from contemporary PONs to NG-PONs. An area that has not been much investigated from the context of NG-PON2 (as defined by the Full Service Access Networking [FSAN] body) is the medium access control. We showcase for the first time the open problem of MAC implementation beyond WDM PONs, in NG-PON2 with multiple-line-rate channels. We propose a solution called OLIMAC, or the Open Lambda Initiative Medium Access Control, as a mechanism to provision bandwidth and guarantee a services framework in flexible wavelength spaced systems. The article describes the implementation of OLIMAC. The OLIMAC solution is shown to work with different protocols showcasing backward compatibility with existing end-user technologies while facilitating voluminous bandwidth to end users. The OLIMAC concept is simulated, and results show the benefit of the proposal as well as how OLIMAC is instructive in the implementation of NGPON2, especially for multirate flexible wavelength-spacing solutions.
    IEEE Network 03/2012; 26(2):49-56. DOI:10.1109/MNET.2012.6172275 · 2.54 Impact Factor
  • Source
    Xiaomin Chen · Admela Jukan · Ashwin Gumaste ·
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    ABSTRACT: Parallel transmission in the optical layer can enable a scalable network migration from low speed interfaces to high speed serial interfaces, such as 100Gbps Ethernet, as they become available. It is based on the principle of inverse-multiplexing which distributes high speed data stream into multiple low rate optical paths. The main challenge in parallel transmission is the differential delay experienced by different paths. Thus so far, electronic buffering has been widely used to compensate for differential delay. However, at very high speed line rates, such as 40Gbps or even 100Gbps, electronic buffering maybe a challenge. In this paper, we study the usage of Fiber Delay Lines (FDLs) for compensation of differential delay in optical parallel transmission in support of high speed Ethernet services. To this end, we formulate the problem of optimal usage of FDLs in optical networks an Integer Linear Programming (ILP) problem. The results are encouraging as they show that discrete nature of delay provided by FDL buffers is not as limiting as expected, and that FDLs carry potential to enable optical parallel transmission without the need to provide large electronic buffers.
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    ABSTRACT: The OpenFlow concept was recently proposed primarily to facilitate policy routing in large enterprise/service provider networks. Carrier Ethernet technologies such as MPLS-TP and PBB-TE are currently considered to be the forerunners in such transport networks. Both these technologies specify the need for a managed control plane. Carrier Ethernet Switch Routers (CESRs) are being proposed for transport functionality in service provider networks. The future of the transport network is to provide for cloud-like services whereby policy routing would be a key enabler technology. The OpenFlow specification is quite in accordance with the implementation of a centralized, unified control plane that is mandatory for Carrier Ethernet. In this paper, we demonstrate the OpenFlow paradigm implementation over CESRs to support next generation cloud applications and services. We showcase architecture, modifications and protocol performance with specific focus on OpenFlow in operator networks. The main novelty of this work is in transforming the OpenFlow controller to co-exist with the network management system of a CESR thus facilitating the CESR to control and interface with the OpenFlow protocol. We adapt the OpenFlow paradigm to an implemented CESR. Hardware results for service performance, network utilization, latency behavior across the network and protection switching are shown. We conclude for the first time, the feasibility of adapting the OpenFlow standard to service provider equipment.
    Networks and Optical Communications (NOC), 2012 17th European Conference on; 01/2012

Publication Stats

827 Citations
84.19 Total Impact Points


  • 2006-2015
    • Indian Institute of Technology Bombay
      • • Department of Computer Science & Engineering
      • • Gigabit Networking Laboratory
      Mumbai, Maharashtra, India
  • 2008-2014
    • Maharashtra Institute of Technology
      • Department of Computer Engineering (MAE)
      Poona, Maharashtra, India
    • University of California, Davis
      Davis, California, United States
  • 2011-2012
    • Nokia Siemens Networks
      Esbo, Uusimaa, Finland
  • 2010
    • Iowa State University
      • Department of Electrical and Computer Engineering
      Ames, Iowa, United States
  • 2007-2010
    • Indian Institute of Technology Ropar
      • Department of Computer Science and Engineering
      Rūpar, Punjab, India
    • Tennessee Technological University
      • Department of Electrical and Computer Engineering
      كوكفل, Tennessee, United States
    • Vidyalankar School of Information Technology
      Mumbai, Mahārāshtra, India
  • 2009
    • University of New Mexico
      Albuquerque, New Mexico, United States
  • 2008-2009
    • Massachusetts Institute of Technology
      Cambridge, Massachusetts, United States
  • 2004-2006
    • University of Texas at Dallas
      • Department of Computer Science
      Richardson, Texas, United States