A Performance Analysis of the Meshed Tree Protocol and the Rapid Spanning Tree Protocol

Loop avoidance is essential in switched networks to avoid broadcast storms. Logical Spanning Trees are constructed on the physical meshed topologies to overcome this issue and preserve the stability of the network. However, during topology changes as the result of a failure, frame forwarding latency or frame loss is introduced when re-converging and identifying new spanning tree paths. The Meshed Tree algorithm (MTA) offers a new approach. Meshed Trees support multiple tree branches from a single root to cut down on re-convergence latency on link failures. A Meshed Tree Protocol (MTP) based on MTA is currently under development as an IEEE standard. MTP is evaluated for convergence delay and frame loss in comparison with Rapid Spanning Tree Protocol (RSTP) on the GENI testbed

Tiered Based Addressing in Internetwork Routing Protocols for the Future Internet

The current Internet has exhibited a remarkable sustenance to evolution and growth; however, it is facing unprecedented challenges and may not be able to continue to sustain this evolution and growth in the future because it is based on design decisions made in the 1970s when the TCP/IP concepts were developed. The research thus has provided incremental solutions to the evolving Internet to address every new vulnerabilities. As a result, the Internet has increased in complexity, which makes it hard to manage, more vulnerable to emerging threats, and more fragile in the face of new requirements. With a goal towards overcoming this situation, a clean-slate future Internet architecture design paradigm has been suggested by the research communities. This research is focused on addressing and routing for a clean-slate future Internet architecture, called the Floating Cloud Tiered (FCT) internetworking model. The major goals of this study are: (i) to address the two related problems of routing scalability and addressing, through an approach which would leverage the existing structures in the current Internet architecture, (ii) to propose a solution that is acceptable to the ISP community that supports the Internet, and lastly (iii) to provide a transition platform and mechanism which is very essential to the successful deployment of the proposed design

Implementing and Testing VLANs in Meshed Tree Protocol

Meshed Tree Protocol (MTP)[1][2] is being developed to overcome the performance challenges faced with older loop avoidance layer 2 protocols like Spanning Tree Protocol (STP)[3] and Rapid STP (RSTP)[5] which have high convergence time, causing a significant delay during initial convergence and subsequent re-convergence in the event of topology change or link failure. This slow convergence is not suitable for the modern high speed and dynamic networks and is being addressed with better performing protocols like MTP which uses Meshed Tree Algorithm (MTA) to form multiple overlapping trees[1]. In this thesis we will implement Virtual Local Area Network(VLAN)[4] for MTP networks using the Global Environment for Network Innovation (GENI)[19] testbed. With the growing size and complexity of modern day networks it is essential to segment a larger network into isolated smaller sections which improve the security, reliability, and efficiency of the network. This is achieved by using VLANs which act as separate smaller networks within a larger network. In this thesis we will discuss the working and benefits of VLANs in the current implementations of STP and how can VLANs be introduced in MTP along with a basic implementation of VLANs in the code developed for MTP by extending it to support Multi Meshed trees, where each meshed tree would cover a VLAN

Root Failure Analysis in Meshed Tree Networks

Mesh topologies play a vital role in switched networks. Broadcast storms due to the loops in Mesh Networks are a major concern in switched networks. Logical spanning trees are constructed using algorithms like spanning tree algorithm to avoid loops and hence address the broadcast storm problem. However, in the event of a topology change or a link failure in the network, it takes time to converge and construct new spanning tree to forward frames. Link State routing and other protocols like Rapid Spanning Tree protocol[2][19] were introduced to address the problems of high convergence times in the basic spanning tree protocol(STP) in the event of network component failures. A much efficient and advanced approach was offered with Mesh Tree Protocol based on the Mesh Tree Algorithm. Mesh Tree Protocol constructs multiple tree branches from a single root and quickly falls back to an alternate path or switch in case of link or switch failures. This cuts down the convergence delays considerably. The Mesh Tree Protocol based on the Mesh Tree Algorithm is currently under development as an IEEE standard. Other major changes in the MTP compared to the already existing protocols is that the root is manually assigned instead of using the root election procedure. This will cut down the delays during instantiation of the protocol but also has risk concerning the action of the protocol if the manually assigned root fails. To address this concern, an enhancement to the Mesh Tree protocol is being researched in this thesis. The idea is to implement a Multiple Meshed Tree algorithm where meshed trees will be constructed from multiple roots. This thesis introduces root redundancy in the Mesh Tree Protocol and will be assessed for performance improvements on root failures in comparison with Rapid Spanning Tree Protocol (RSTP) which re-elects a root switch on the current root switch failure

An SDN controller-based framework for anomaly detection using a GAN ensemble algorithm

Of recent, a handful of machine learning techniques have been proposed to handle the task of intrusion detection with algorithms taking charge; these algorithms learn, from traffic flow examples, to distinguish between benign and anomalous network events. In this paper, we explore the use of a Generative Adversarial Network (GAN) ensemble to detect anomalies in a Software-Defined Networking (SDN) environment using the Global Environment for Network Innovations (GENI) testbed over geographically separated instances. A controllerbased framework is proposed, comprising several components across the detection chain. A bespoke dataset is generated, addressing three of the most popular contemporary network attacks and using an SDN perspective. Evaluation results show great potential for detecting a wide array of anomalies

Modelling and Design of Resilient Networks under Challenges

Communication networks, in particular the Internet, face a variety of challenges that can disrupt our daily lives resulting in the loss of human lives and significant financial costs in the worst cases. We define challenges as external events that trigger faults that eventually result in service failures. Understanding these challenges accordingly is essential for improvement of the current networks and for designing Future Internet architectures. This dissertation presents a taxonomy of challenges that can help evaluate design choices for the current and Future Internet. Graph models to analyse critical infrastructures are examined and a multilevel graph model is developed to study interdependencies between different networks. Furthermore, graph-theoretic heuristic optimisation algorithms are developed. These heuristic algorithms add links to increase the resilience of networks in the least costly manner and they are computationally less expensive than an exhaustive search algorithm. The performance of networks under random failures, targeted attacks, and correlated area-based challenges are evaluated by the challenge simulation module that we developed. The GpENI Future Internet testbed is used to conduct experiments to evaluate the performance of the heuristic algorithms developed

MultiPaths Revisited - A novel approach using OpenFlow-enabled devices

This thesis presents novel approaches enhancing the performance of computer networks using multipaths. Our enhancements take the form of congestion- aware routing protocols. We present three protocols called MultiRoute, Step- Route, and finally PathRoute. Each of these protocols leverage both local and remote congestion statistics and build different representations (or views) of the network congestion by using an innovative representation of congestion for router-router links. These congestion statistics are then distributed via an aggregation protocol to other routers in the network. For many years, multipath routing protocols have only been used in simple situations, such as Link Aggregation and/or networks where paths of equal cost (and therefore equal delay) exist. But, paths of unequal costs are often discarded to the benefit of shortest path only routing because it is known that paths of unequal length present different delays and therefore cause out of order packets which cause catastrophic network performances. Further, multipaths become highly beneficial when alternative paths are selected based on the network congestion. But, no realistic solution has been proposed for congestion-aware multipath networks. We present in this thesis a method which selects alternative paths based on network congestion and completely avoids the issue of out of order packets by grouping packets into flows and binding them to a single path for a limited duration. The implementation of these protocols relies heavily on OpenFlow and NOX. OpenFlow enables network researchers to control the behavior of their network equipment by specifying rules in the routers flow table. NOX provides a simple Application Programming Interface (API) to program a routers flow table. Therefore by using OpenFlow and NOX, we are able to define new routing protocols like the ones which we will present in this thesis. We show in this thesis that grouping packets together, while not optimal, still provides a significant increase in network performance. More precisely we show that our protocols can, in some cases, achieve up to N times the throughput of Shortest Path (SP), where N is the number of distinct paths of identical throughput from source to destination. We also show that our protocols provide more predictable throughput than simple hash-based routing algorithms. Todays networks provide more and more connections between any source- destination pair. Most of these connections remain idle until some failure occurs. Using the protocols proposed in this thesis, networks could leverage the added bandwidth provided by these currently idle connections. Therefore, we could increase the overall performance of current networks without replacing the existing hardware

A survey of Virtual Private LAN Services (VPLS): Past, present and future

Virtual Private LAN services (VPLS) is a Layer 2 Virtual Private Network (L2VPN) service that has gained immense popularity due to a number of its features, such as protocol independence, multipoint-to-multipoint mesh connectivity, robust security, low operational cost (in terms of optimal resource utilization), and high scalability. In addition to the traditional VPLS architectures, novel VPLS solutions have been designed leveraging new emerging paradigms, such as Software Defined Networking (SDN) and Network Function Virtualization (NFV), to keep up with the increasing demand. These emerging solutions help in enhancing scalability, strengthening security, and optimizing resource utilization. This paper aims to conduct an in-depth survey of various VPLS architectures and highlight different characteristics through insightful comparisons. Moreover, the article discusses numerous technical aspects such as security, scalability, compatibility, tunnel management, operational issues, and complexity, along with the lessons learned. Finally, the paper outlines future research directions related to VPLS. To the best of our knowledge, this paper is the first to furnish a detailed survey of VPLS.University College DublinAcademy of Finlan