Sameer Qazi

Scalable Resilient Overlay Networks Using Destination-Guided Detouring

Routing policies used in the Internet tend to be restrictive, limiting communication between source-destination pairs to one path, when often better alternatives exist. To avoid route flapping, recovery mechanisms may be dampened, making adaptation slow. Unstructured overlays have been widely used to mitigate the issues of path and performance failures in the Internet by routing through alternate paths via overlay peers. The construction of such routing overlays often does not take into account the physical topology of the network, which necessitates that all overlay nodes aggressively probe paths to check performance, limiting scalability. In this paper, we analyze a topologically-aware architecture to estimate end-to-end path availability for service on the Internet. We propose destination-guided detouring via resilient overlay networks (DG-RON); a distributed coordinate-based overlay architecture, which uses landmark based heuristics for scalable end-to-end path discovery. Simulations show that DG- RON can predict alternate paths with a high success rate.

Cyber Security Backdrop: A SCADA testbed

Supervisory Control and Data Acquisition (SCADA) systems are traditionally proprietary and well protected. Due to increasing use of commercial/open source technology and communication protocols, there are growing concerns about the associated security threats. SCADA networks are usually employed in critical infrastructure, therefore, not much technical data of the actual systems is accessible to the research community. Most of the researchers simulate the SCADA functioning through development of testbed. Such projects are usually expensive and requiring financial sponsorship. In this paper we present a simple, inexpensive and flexible approach to develop a SCADA testbed utilizing TrueTime, a MATLAB/ Simulink based tool. The paper describes TrueTime simulation blocks, our control system, simulation of Denial of Service (DoS) attack and its effects. The main aim was to assess the effectiveness and suitability of TrueTime for the intended use in the development of a larger scale SCADA testbed. The results shown reflect that TrueTime can be effectively used for the purpose of SCADA network simulations and collection of necessary data for security analysis.

Using Type-of-Relationship (ToR) Graphs to Select Disjoint Paths in Overlay Networks

Routing policies used in the Internet can be restrictive, limiting communication between source-destination pairs to one path, when often better alternatives exist. To avoid route flapping, recovery mechanisms may be dampened, making adaptation slow. Unstructured overlays have been widely proposed to mitigate the issues of path and performance failures in the Internet by routing through an indirect-path via overlay peer(s). Choice of alternate-paths in overlay networks is a challenging issue. Ensuring both availability and performance guarantees on alternate paths requires aggressive monitoring of all overlay paths using active probing; this limits scalability when the number of overlay-paths becomes large. An alternate technique to select an overlay-path is to bias its selection based on physical disjointness criteria to bypass the failure on primary-path. In this paper, we show how type-of-relationship (ToR)-Graphs can be used to select maximally-disjoint overlay-paths.

On Issues of Multi-path Routing in Overlay - Networks Using Optimization Algorithms

Routing policies used in the Internet can be restrictive, limiting communication between source-destination pairs to one path, when often better alternatives exist. To avoid route flapping, recovery mechanisms may be dampened, making adaptation slow. Overlays have been widely proposed to mitigate the issues of path and performance failures in the Internet by routing through an indirect-path via overlay peer(s). Choosing alternate-paths in overlay networks is a challenging issue. Guaranteeing both availability and performance guarantees on alternate paths requires aggressive active probing of all overlay paths, which limits scalability when the number of overlay-paths becomes large. If path correlations could be determined, multi-media applications can benefit greatly if their traffic could be sent over multiple uncorrelated paths. Statistical approaches have been previously proposed for establishing path correlation for multi-path routing; In this paper we test the efficacy of such approaches in Internet scale overlay networks using real-world datasets.

Network tomography using genetic algorithms

Wide Area Network monitoring has become increasingly important to deliver QoS demanded by customers of Skype, Facebook, Twitter etc or to detect/prevent attacks on networks carrying out sensitive tasks e.g. SCADA networks controlling the electrical grid. Unfortunately the task of monitoring paths becomes increasingly prohibitive as the size of the network increases. Fortunately, recent research has devised interesting approaches for Network Tomography using dimensionality reduction to first simplify the scope of the problem by choosing vital network parameters that must be monitored and then applying statistical techniques to make accurate prediction for unmonitored network parameters from monitored; thus making the problem of monitoring large networks scalable. The latter part of network parameter prediction falls in the domain of optimization problems. Recent work on biologically inspired genetic approaches to solving such optimization problems offers much flexibility in finding an optimal solution. We investigate the feasibility on using genetic algorithms for the network tomography problem.

Evaluation of Performance of Genetic Algorithms for Network Tomography

Wide Area Network monitoring has become increasingly important to deliver Quality of Service (QoS). Fortunately recent research has devised interesting approaches for scalable network monitoring using Linear Modeling. However, such linear models involve an underdetermined or over-determined system of equations with no unique solution. Finding an optimum solution in such scenario involves posing the problem as a constrained optimization problem. However, such constructions can involve a variety of options of objective function selection. For example one approach in objective function selection is driven by pre-specifying traits in the desired solution; other approaches pose no such constraints. More recent approaches combine the merits of various approaches for best optimum solution. In this paper we propose the use of genetic algorithms to solve these optimization problems since they provide an ideal platform in using multiple pronged objective functions to bridge the dichotomy between the various methods available and come up with the best solution. Our findings in this paper are that genetic algorithms can surpass the conventional approaches (of convex optimization) in solution construction and often surpasses performance of conventional approaches while having acceptable computation times.

Migrate to IPv6 on 6PE with MPLS-TE: Questions on Feasibility and Reluctance in Deployment?

Due to the exhaustion of IPv4 addresses, the transition to IPv6 has already begun using various transition mechanisms. In this paper comparison between two transition mechanism 6PE and 6to4 tunneling over MPLS (Multiprotocol Label Switching) based network has been performed. The experimental platform used is based on GNS3/Dynagen using emulated routers on which multiple TCP and UDP flows were generated between separated IPv6 network traversing through IPv4 based core. Traffic were generated using both transition mechanism and are compared to native IPv4 based MPLS network. Performance metric used are end-to-end delay, jitter and throughput, these parameters are also analyzed statistically using ANOVA, F-Test and T-Test to support a conclusion. Further, MPLS Traffic-Engineering (TE) using RSVP-TE signalling is applied, describing the implementation and performance test and analysis of TE tunnels on 6PE for IPv6 traffic. The same test-bed is used to implement and observe MPLS-TE behavior and throughput of 6PE based MPLS-TE to that of native IPv4 based MPLS-TE. Concluding, throughput of 6PE and 6to4 is around 99% and 96%, respectively, as compared to that of native IPv4.

Lead Me, Follow Me, or Get Out Of My Way: Cluster Head Selection Algorithm for Mobile-WSNs

Cluster-based routing protocols have significant impact on the energy dissipation and lifetime of wireless sensor networks. In this paper, the basic Low Energy Adaptive Clustering Hierarchy (LEACH) protocol has been modified with our proposed LEACH-Mobile Average Energy-based (LEACH-MAE) protocol to overcome shortcomings in order to support mobility along with a new average energy?based cluster head selection technique. Our simulation in Network Simulator 2 shows that the proposed LEACH-MAE algorithm improves network lifetime up to 25% and helps to maintain equal distribution of energy resources among the sensor nodes.