Sayed Hussein

A comparative analysis of network dependability, fault-tolerance, reliability, security, and survivability

A number of qualitative and quantitative terms are used to describe the performance of what has come to be known as information systems, networks or infrastructures. However, some of these terms either have overlapping meanings or contain ambiguities in their definitions presenting problems to those who attempt a rigorous evaluation of the performance of such systems. The phenomenon arises because the wide range of disciplines covered by the term information technology have developed their own distinct terminologies. This paper presents a systematic approach for determining common and complementary characteristics of five widely-used concepts, dependability, fault-tolerance, reliability, security, and survivability. The approach consists of comparing definitions, attributes, and evaluation measures for each of the five concepts and developing corresponding relations. Removing redundancies and clarifying ambiguities will help the mapping of broad user-specified requirements into objective performance parameters for analyzing and designing information infrastructures.

Network Dependability, Fault-tolerance, Reliability, Security, Survivability: A Framework for Comparative Analysis

A number of qualitative and quantitative terms are used to describe the performance of what has come to be known as information systems, networks or infrastructures. However, some of these terms either have overlapping meanings or contain ambiguities in their definitions presenting problems to those who attempt a rigorous evaluation of the performance of such systems. The phenomenon arises because the wide range of disciplines covered by the term information technology have developed their own distinct terminologies. This paper presents a systematic approach for determining common and complementary characteristics of five widely-used concepts, dependability, fault-tolerance, reliability, security, and survivability. The approach consists of comparing definitions, attributes, and evaluation measures for each of the five concepts and developing corresponding relations. Removing redundancies and clarifying ambiguities will help the mapping of broad user-specified requirements into objective performance parameters for analyzing and designing information infrastructures

Performance analysis of VoIP codecs over multi-rate EDCA

Enhanced Distributed Channel Access (EDCA) is a mandatory part of the IEEE 802.11e standard which provides Medium Access Control (MAC) layer solution for Quality of Service (QoS) provisioning in Wireless Local Area Networks (WLANs). It is a contention based protocol which prioritizes channel access to QoS traffic using four Access Categories (ACs). In this paper, we introduce the performance evaluation of high priority Voice over Internet Protocol (VoIP) traffic over EDCA in multi-rate WLAN. In a multi-rate environment, the channel physical transmission rate is changed by the Access Point (AP) as the stations move towards or away from the AP. The AP performs rate adaptation on each frame according to the channel condition or signal quality that the frame is likely to experience when stations are considered mobile. We implement EDCA at the MAC layer over the physical layer of IEEE 802.11b radios using the network modeling and simulation tool QualNet. We simulate multiple VoIP nodes in a single QoS-enabled Basic Service Set (QBSS) with one QoS-enabled AP (QAP). The performance of each VoIP node is evaluated with three VoIP codecs. We first use codecs without jitter buffer and evaluate jitter with other performance parameters. The simulations are repeated for different codecs with jitter buffer. The effect of jitter buffer on Jitter, Delay and Mean Opinion Score (MOS) for each VoIP node is compared with other codecs in stationary and mobile environments. Simulation results show the effectiveness of using jitter buffer and its limitations in a multi-rate environment.

QoS Mapping: A Framework Model for Mapping Network Loss to Application Loss

Todays Internet provides only a single Class of Service (CoS) to all of its services (e.g., Multimedia, Data, Audio), namely the best-effort service. This service does not make any guarantees on the Quality of Service (QoS) an application receives. The continuous demands for QoS guarantees have led to the introduction of various network-layer mechanisms that provide some end-to-end QoS assurance including MPLS, Integrated Service Model (IntServ), and Differentiated Service Model (DiffServ). However, the QoS mapping between the network-layer and the application-layer is still a challenge and needs to be addressed. To guarantee and end-to-end QoS, it is essential to map QoS parameters between these layers. A framework for investigating the mapping of the packet loss rate as an important QoS parameter is presented here. The network QoS performance characteristic for the loss parameter is mapped from lower to upper layer in a quantifiable way.

Towards a Standardized Terminology for Network Performance

The integration of the products of diverse fields, including the human component, into complex systems has created major difficulties in the development of efficient mechanisms for analyzing system performance. One of the problems can be traced to the variety of terminologies used in describing performance across different fields. A designer or user is faced with vague terms that may be complementary, synonymous, or some combination thereof. There is a need to develop a common understanding of the meaning of widely used terms without reference to a specific discipline. The work described in this paper aims to develop a framework that helps identify a set of performance indicators for complex systems, such as information infrastructures. The objective is not to propose yet another concept, but rather to identify from the existing concepts the proper definitions, attributes, intersections, and evaluation measures. Dependability, fault-tolerance, reliability/availability, security, and survivability are used as representative examples for describing the proposed framework. This framework could eventually help furnish the basis towards adoption of standard terminology.

Prototype Genomics-Based Keyed-Hash Message Authentication Code Protocol

The evolving nature of the internet will require continual advances in authentication and confidentiality protocols. Nature provides some clues as to how this can be accomplished in a distributed manner through molecular biology. Cryptography and molecular biology share certain aspects and operations that allow for a set of unified principles to be applied to problems in either venue. A DNA (Deoxyribonucleic acid) inspired hash code system is presented that utilizes concepts from molecular biology. It is a keyed-Hash Message Authentication Code (HMAC) capable of being used in secure mobile Ad hoc networks. It is targeted for applications without an available public key infrastructure. Ad hoc does not mean the users are completely unknown to each other. They could be part of a military unit, police, emergency workers, mobile vendors, or any collection of users in a common geographical area that wish communicate in a region lacking a Public Key Infrastructure (PKI). Mechanics of creating the HMAC are presented as well as a prototype HMAC protocol architecture.

A Comparative Overview IEEE 802.16e QoS Scheduling Algorithms

One of the most significant promises in today’s integrated packet-switched broadband wireless networks (such as WiMAX) is providing Quality of Service (QoS) guarantees to data, voice and video applications. These applications range from real-time applications with stringent QoS requirements, to best effort applications with no required guarantees. These applications with different QoS requirements interact with one another when they are multiplexed at the same output links. Lack of control during packet interactions will degrade network performance. Using scheduling algorithms to provide QoS, wireless networks are able to integrate applications with a wide range of traffic characteristics. We present an overview of QoS mechanism in the media access control (MAC) sublayer of WIMAX wireless networks and provide a comparative overview of scheduling schemes architecture proposed in WIMAX research literature.

Adaptive Self-Correcting Floating Point Source Coding Methodology for a Genomic Encryption Protocol

the problem of creating an adaptive source coding algorithm for a genomic encryption protocol using a small alphabet such as the nucleotide bases represented in the genetic code. For codewords derived from an alphabet of N plaintext with probability of occurrence, p, we describe a mapping into a floating point representation of the codewords which are translated into genomic codewords derived from a novel modification of the Shannon-Fano-Elias coding process. Errors in the reverse decoding process are processed through an adaptive, self-correcting codebook to determine the best fit codeword decoding solution. A genetic algorithmic approach to error correction within the source coding is also summarized.

A framework for network reliability through QoS mapping between lower and upper layers

The majority of todaypsilas infrastructures are vulnerable to various disruptions that affect their essential services. Consequently, different research programs have been aiming at lowering such disruptions. In fact, the problem of designing systems with dependability, reliability, or security characteristics has long been acknowledged as an area for further research, and has received a substantial amount of attentions in the last few years by many different organizations and institutes. However, there are various inconsistent concepts and terminologies that are commonly used to describe the performance of systems (e.g., high-confidence, survivable, trustworthy, and robust). Some of these concepts are quantitative while others are qualitative, and it is a challenge to analyze and evaluate the performance of systems subjectively. Therefore, in this research, we are relating the various subjective concepts to a simple measurable concept which is the reliability concept, and based on analyzing this concept in the high-speed IP-based network environment, the reliability concept is further expressed by the quality of service (QoS). A QoS mapping between the lower and upper layers loss rate performance parameter has been developed. Further, the impact of the lower layer packets loss on the upper layer frames quality has been investigated. This mapping allows better understanding of the technical network parameters from the applicationpsilas perspective of the service level agreement (SLA) and it balances the reservations of the right resources.

Toward A Reliable Network Design: A QoS Mapping Framework

No doubt that the information technology field is filled with various qualitative and quantitative concepts that are used to describe the desired performance for the network user or designer. The most common performance indicator concept is the reliability concept. Based on analyzing this concept in an IP network environment, the reliability concept is further expressed by the quality of service (QoS). Any regular network user definitely cares about the reliability of the services he perceives. This reliability in fact depends on the reliability of the underlying network. Therefore, the upper layer subjective requirements need to be transparently translated into lower layer objective ones. This paper presents a systematic framework for mapping the lower-layer network QoS performance parameter embodied by the packet loss rate into the upper-layer application QoS in an objective quantifiable way. In fact, currently with the advanced highspeed networks, the focus of the IP network performance is shifting from scalability, throughput and utilization benchmarks to guaranteeing loss bounds for different applications and users. Thus, this mapping will surely allow better and reliable system design and understanding of the technical network parameters from the applications perspective of the service level agreement (SLA).