Systems and Network Infrastructure Integration

Design, Implementation, Safety and Supervision

Saida Helali

• Éditeur: Wiley-ISTE
• Année: 2020
• ISBN:
  9781119779940
• Édition: 1
• Sujet: Computer Science
• Sous-sujet: Computer Engineering

IT infrastructures are now essential in all areas and sectors of human activity; they are the cornerstone of any information system. Thus, it is clear that the greatest of care must be given to their design, implementation, security and supervision in order to ensure optimum functionality and better performance. Within this context, Systems and Network Infrastructure Integration presents the methodological and theoretical principles necessary to successfully carry out an integration project for network and systems infrastructures. This book is aimed at anyone interested in the field of networks in general. In particular, it is intended for students of fields relating to networks and computer systems who are called upon to integrate their knowledge and skills, gained throughout their academic study, into a comprehensive project to set up a complete infrastructure, while respecting the necessary specifications.

8
Quality of Service and High Availability

“Quality is never accidental; it is always the result of intelligent effort.”

John Ruskin

– Understanding the concept of QoS and its objectives, as well as its usefulness for current IT infrastructures.

– Understanding the basic principles of QoS in networks (needs, structure, configuration options).

– Learning how to use data flow classification, improved enqueuing, and advanced load management techniques.

– Differentiating between QoS protocols or standards in the link and network layers.

– Understanding high availability mechanisms, in this case redundancy and backup.

– Describing the objectives and main protocols of level 2 and 3 redundancies.

– Understanding the general functioning of load balancing and data replication.

8.1. Introduction

These days, IT infrastructures offer more and more diverse services and serve as a framework for a wide range of applications. This varied offer must be accompanied by a service quality of assurance in order to ensure end-user satisfaction.

In reality, and in a context of convergence, services with different characteristics and different requirements must be provided by a single infrastructure that must ensure their proper functioning consistent with the levels of service required, or SLA (Service Level Agreement). Therefore, any plan to set up a network infrastructure must include and address the service quality aspect.

In the same vein, an effort to achieve high availability of the various components of the network infrastructure, mainly through redundancy, is certainly in order. This high availability helps to avoid crashes and to balance loads in order to optimize the functioning of the network infrastructure.

8.2. Quality of service

8.2.1. Motivation

Quality of Service (QoS) played a secondary role in the original design of the TCP/IP protocols, designed to transport data from asynchronous applications, that is, services such as file transfers, e-mail and terminal access.

However, some applications, such as VoIP and Video IP, require an adequate network QoS: controlled latencies, low jitter and low packet loss, as well as guaranteed bandwidth. This is the only way quality is guaranteed for the end-user. QoS relies on defined control mechanisms that are linked to traffic management in order to influence transport network metrics in relation to flows of information transmitted.

QoS is not a supplementary functionality like an extension for a network infrastructure, then, but the result of a large number of coordinated measures that must be anchored in the basic design of a network infrastructure. It is important to note here the interaction of the various layers of the OSI model and their requirements; indeed, it is useful to determine whether it is possible to have mechanisms in a layer that enable tolerance against malfunctions in the underlying layers.

The methods required will be discussed in this chapter. The functional elements of a network that are necessary for good QoS, and how they can be implemented with current technologies, will also be presented.

Prioritization or configuration of ...