Specificity of the Internet

In this section we present some of the important characteristics of the Inter-net Inter-network that will support or constrain its study with a Causal approach as presented in Chapter 3.

A causal approach to the study of Telecommunication networks

14 1. INTRODUCTION AND BACKGROUND The Internet has grown very fast since its creation in the 1980s as a world wide network of interconnected networks. According to the International Telecom-munication Union (ITU) 44% of the households in the world have an Internet access in 2014 and more than 40% of the world uses Internet daily. For the developed countries these two percentages are close to 80%. Consequently, these numbers are very likely to increase in the coming years with the different projects led by societies like Google or Facebook to improve the connectivity for developing countries. According to ITU the percentage of people using Internet has doubled in the last seven years.

The deployment and adoption of the Internet network has been supported by the development of several access technologies (ADSL, Mobile, Fiber, Satel-lite), the multiplication of actors participating in its development (ISP, Content provider, Online service companies, Developers) and in its growth. Most im-portantly, an important number of applications, services and usages exist and is being created to help Internet network users in their daily life, with new appli-cations being designed every day.

Technologies

In this section, we briefly present some of the common technologies used by the Internet users to access Internet. The aim of this section is not to give an ex-haustive list but, through the presentation of some of the common technologies supporting the Internet, to show the heterogeneity of the Internet technologies and of the models of user Internet access.

Along with the Internet expansion, the number of technologies to access the Internet has also grown very fast and heterogeneous. For wired connections, European countries, like France, often use Asynchronous Digital Suscriber Line (ADSL) while in U.S. there exists a common alternative based on tele-vision service infrastructure called Cable Internet access. In the past years, we have seen the different Internet Service Providers (ISPs) proposing to their cus-tomers Fiber To The Home (FTTH) accesses that allow higher transfer speed.

Alternative solutions such as power-line Internet also exist that allow access to the Internet in areas where the installation of new equipment is often compli-cated. Most companies and universities use Local Area Network (LAN) solu-tions where Ethernet is the most spread wired access technologies.

In addition to wired access, there exist several wireless technologies a very common one being the WiFi (802.11) technology. However, with the advent of smart phones, mobile broadband access has become the technology most commonly used to access the Internet network. According to ITU 2014 report 84% of the people living in a developed countries has an active mobile broad-band subscription and 21% for the developing countries. According toCisco Vi-sual Networking Index: Global Mobile Data Traffic Forecast Update, 2014 – 2019,

1.2. TELECOMMUNICATION NETWORKS 15 the global mobile data traffic grew 69% in 2014. The comScore company™

announced in February 2014 that mobile telephone usage overtook laptop in Internet usage. Finally, there are cases where remote areas rely on Satellite broadband access to access Internet. This solution is known to be expensive and implies important delays.

Actors

The understanding of all the actors participating in the existence, diffusion, evo-lution and usage of the Internet network is out of the topic of our work. Inter-net evolution is guided by the rule of supply and demand in terms of services and contents. There should exist more economical agreements than there exist telecommunication operators, all these agreements define service level agreements (SLA) between the different parties and impact the quality of ser-vice of the end users. Obviously, the evolution of the Internet network is also supported by the evolution of the different technologies supporting its com-munication (Physical links: Fiber, Broadband access, WiMax, Internet nodes:

Routers, Servers, Super computers, End user devices: Tablets, Connected Devices, Cars manufacturers). On the other hand, in addition to the “connectiv-ity providers´´, there is an increasing number of content, or service, providers developing new solutions for all the use cases that one could need or think of (Home automation, Cloud Computing, Online Gaming, Video On Demand, Social Networks, News,. . . ). It is then not possible to list all the actors that, altogether, form the Internet network in its global definition.

However, it is important to notice that from the Internet Service Providers to the Online Content providers there is an important number of entities working together to provide to end users an access to the different resources available on the Internet. Each of these actors plays a role in the Quality of Experience (QoE) of the end users. It is the ability and quality of the interactions of these actors that defines the end user QoE. Understanding how the service of an actor of the network impacts the service of another and finally the end user experience is a complex, if not impossible, problem that will be discussed later in this chapter.

Usage

There is a large number of services based on the Internet network. Some of the most common services fall in the following categories: Mail, File exchange, Web browsing, or Video Streaming. However, the Internet users being more and more numerous, new categories of services appear very often. An example is the paradigm of the cloud computing (lie Amazon Web Service) that has A causal approach to the study of Telecommunication networks

16 1. INTRODUCTION AND BACKGROUND seen its evolution and adoption boosted by the distributed databases and the computing power of computer clusters.

It is interesting to notice that different usages of the Internet network require different qualities of service. For example telephony (Voice Over IP) is more sensitive to delay and delay variations than it is to packet losses. On the op-posite, while a user is concerned by the delay while accessing a file, a special care is taken in file transfers to recover from packet losses.

The point that we try to stress here is the increasing number of services de-veloped in the Internet network, each of which having different requirements in terms of performance and reacting differently to network failures or malfunc-tioning.