Virendra Singh Shekhawat

A Novel Packet Switch Node Architecture for Contention Resolution in Synchronous Optical Packet Switched Networks

Packet contention is a key issue in optical packet switch (OPS) networks and finds a viable solution by including optical buffering techniques incorporating fiber delay lines (FDLs) in the switch architecture. The present paper proposes a novel switch architecture for packet contention resolution in synchronous OPS network employing the packet circulation in FDLs in a synchronized manner. A mathematical model for the proposed switch architecture is developed employing packet queuing control to estimate the blocking probability for the incoming traffic. The switch performance is analyzed with a suitable contention resolution algorithm through the computer simulation. The simulation results substantiate the proposed model for the switch architecture.

Weight Based Edge Disjoint Path Routing and Wavelength Assignment (WEDP-RWA) Algorithm for WDM Networks

In this paper the problem of routing and wavelength assignment (RWA) in optical wavelength division multiplexing (WDM) networks has been addressed and a new weight based edge disjoint path (EDP) algorithm for RWA has been proposed to optimize the wavelength resources in a wavelength routed WDM networks. The simulation results reveal that the network topology characteristics and link utilization factor have a significant impact on light path selection for traffic routing to minimize the required number of wavelengths. The weight based RWA solution reports significant improvement in wavelength utilization in particular for large network with increase in the call request for a source destination pair.

MPLS based hybridization in SDN

The new paradigm of Software Defined Networking (SDN) although has great potential to address the complex problems presented by enterprise networks, it has its own deployment and scalability issues. Further, a full SDN deployment has its own business and economic challenges. A smooth transition from legacy networks to SDN (disruption free, accommodating budget constraints, with progressive improvement in network management) requires a hybrid networking model as an inevitable intermediate step; that allows heterogeneous paradigms to function together while the full transition is realized in phases. Therefore, the need of the hour is to develop an incremental deployment strategy that caters to the needs of the organization. We present here a class-based hybrid SDN model for Multi Protocol Label Switching (MPLS) networks. We discuss the model, design, components, their interactions, advantages and drawbacks. We also present a n implementation and evaluation of a prototype. In legacy networks, MPLS architecture closely resembles SDN paradigm in terms of separation of control and data planes, flow-abstraction etc. Moreover, ISPs have preferred MPLS over the years due to benefits of virtual private networks and traffic engineering. The central idea is to partition traffic using forwarding equivalence classes at the ingress router, the rules of which can be updated via a centralized controller using OpenFlow. Therefore, we aim to use the standard MPLS data-plane together with a control-plane based on OpenFlow to come up with a systematic incremental deployment methodology as well as a hybrid operation model

Latency and Routing Efficiency Based Metric for Performance Comparison of DHT Overlay Networks

The general method available for comparison between the Distributed Hash Table (DHT) based structured overlay networks are average latency per successful lookup and percentage of successful lookups. For a DHT based lookup service with lookup retries for failed lookups, both average latency per successful lookup as well as percentage of successful lookups are key to evaluate the performance. Although, average latency per successful lookup may be less for a DHT overlay protocol, failure of lookups at high churn rates may degrade the protocols performance if its routing efficiency is less. On the other hand, just routing efficiency is not sufficient to measure the performance of a DHT since an overlay network having higher routing efficiency may not have a good performance due to high average latency per successful lookup. We have developed a metric for DHT comparison which incorporates both average latency per successful lookup and routing efficiency in scenarios where applications do lookup retries. We have also modeled three different timeout mechanisms while developing the performance metric. The paper also incorporates a model where the probability of failure of a lookup is increasing at every retry of lookups.

A token passing approach for circle formation by multiple mobile robots

This paper proposes a weakly centralized distributed approach for positioning multiple mobile robots in a circular formation based on token passing. The problem of the circle formation with multiple robots which are arbitrarily placed on a 2D plane requires all robots to be uniformly positioned (i.e., at an equal angular distance of 2π/N, where N = number of robots) on the circle circumference. The suggested approach is a leader-follower approach wherein it is the leader robot which computes the uniform positions on the circle circumference for all the follower robots. The problem of circle formation is divided into two sub-problems (a) leader selection and (b) finding enviable positions for the follower robots from the set of uniform positions computed by the leader robot. Both these problems are solved by token passing so as to reduce communication load on both the leader and the follower robots. The introduction of token passing makes it a weakly centralized framework thereby reducing the burden on the leader robot.

Resource efficient survivability approach for resilient WDM optical networks

This paper presents an overview of various existing network survivability techniques implemented in optical WDM networks and proposes an efficient network survivability approach. The proposed approach works on the principle of preplanned protection which adopts dynamic restoration strategy to improve the wavelength usages and call connection rate under single link failure scenario. The resiliency in the network is achieved through backup paths utilizing pre-provisioning at the time of connection establishment process and also by reserving wavelengths during the failure recovery time. The proposed approach has been analyzed and compared with the preplanned protection and dynamic restoration method through simulation to confirm an improvement in call acceptance ratio.

A novel multi-path data transmission algorithm for wavelength routed optical WDM networks

This paper investigates the traffic handling capability of wavelength routed optical WDM (Wavelength Division Multiplexing) network, exploiting multi-path transmission under a proposed adaptive link weight algorithm. Data transmission through multiple paths improves the connection probability by reducing the wavelength hold time on a link. Further it reduces traffic load on bottleneck links by distributing traffic over multiple paths in the network. The proposed algorithm uses multiple edge disjoint paths to mitigate the congestion problem through load balancing and improves the reliability. We study the effectiveness of the proposed algorithm using network simulation and estimate the call blocking probability for the given resources through a single and multi-path transmission to establish the superiority of the latter approach.