The subject "Introduction to Computer Networks" (ICN) is a fundamental part of the training of future computer and communications engineers. The objective of the course is for students to understand the functioning of computer networks in general, and the Internet in particular, so that they will be able to develop, in the future, devices and applications with communication capabilities that make good use of these networks.



The ICN course is designed around the concept of "layered communications architecture": a large, complex problem is broken down into simpler "layers", starting with the transmission of a bit over a medium and ending with the development of distributed applications. At each layer, students will understand which problems are addressed and the corresponding solutions. The TCP/IP protocol and services architecture, which is the basis of the Internet, is used to exemplify all the concepts explained in the lectures.



Many of the devices in use today (computers, cell phones, tablets, smart-TVs, etc.) connect to the Internet, or to each other, using various link technologies: Bluetooth, 4-5G, Wi-Fi, Ethernet, cable, home fiber, etc. Thinking of an unconnected device is hardly conceivable today. IT engineers must know the characteristics (advantages, limitations) of these communication technologies in order to analyze their performance and cost. This information is decisive for selecting the most appropriate service for a given application, or for designing an application that takes full advantage of the services available.



This course will provide the theoretical foundations of computer networks, allowing students to understand current and future communication technologies. In addition, students will participate in laboratory sessions to carry out practical activities with real and simulated (but totally realistic) network equipment: computers, switches, routers, firewalls... These laboratory sessions are an essential complement to the theoretical classes, allowing students to consolidate the concepts examined there and to learn about the daily activities of a network professional.

The objective of this subject is to provide students with knowledge about the basic concepts and techniques used in TCP/IP-based computer networks, with special focus on the Internet.



Students will learn the internals of the TCP/IP protocol suite and its implementation in computers and other devices. They will learn how the Internet works and, from that knowledge, understand how network infrastructures and services can be implemented and managed.



Regular classes are mostly devoted to applied theory, with some sessions used to propose and solve problems. These classes are complemented with lab sessions. Lab activities have a dual purpose: (1) as training, using tools and equipment that will form part of their future professional duties and (2) as a way to enhance the comprehension of concepts and techniques described in the regular class sessions.



In relation to the coded skills for the degree in Informatics, this subject will focus on RI5 (Capacity to understand, manage and maintain systems, services and applications), RI11 (Ability to understand and apply the characteristics, functionality and structure of distributed systems, computer networks and the Internet in order to design, analyze and implement applications based on them) and RI13 (Ability to understand and apply the necessary tools and mechanisms to store, process and access information systems, including web-based ones). We will also develop skills coded as C4 (Capacity to define, evaluate and select hardware and software platforms for the development and implementation of systems, services and applications), C6 (Capacity to conceive and develop centralized or distributed computing systems and architectures integrating hardware, software and networks), C9 (Ability to solve problems with initiative, autonomy and creativity; efficient decision making; capacity to communicate and transmit knowledge; abilities and skills related to the profession of engineer in computer science) and C10 (Ability to carry out measurements, calculations, assessments, valuations, appraisals, studies, reports, planning of tasks and other similar works in the computing field).

CLASS SESSIONS

Chapter 1. Introduction.

What is the Internet. How to connect to the Internet. Internal structure of the Internet. Characteristics of communication channels. Communication protocol architectures. The TCP/IP protocol suite.

Chapter 2. Link layer.

The medium access layer. LANs and WLANs. Error correction and detection. Medium access control protocols. Physical addresses. Ethernet technologies. PPP. MPLS.

Chapter 3. IP networks.

The IPv4 protocol. IPv4 addressing. IP routing. Automatic host configuration (DHCP). Network address translation (NAT). IPv6.

Chapter 4. Transport protocols and services.

Reliable data transfer. Congestion control. UDP and TCP. Client-server communication.

Chapter 5. Network security

Firewalls. Cryptography. Certificates and digital signatures. Security at the different layers: WiFi security, VPNs, SSL/TLS.



LABORATORY SESSIONS

2. Introduction to a network simulation environment. Switching. Device management.

1. Advanced switching and device management. Introduction to routing.

3. Interconnecting networks. Forwarding tables. Routing protocols.

4. Managing complex networks with DHCP and NAT.

5. Realistic traffic. Basic firewalling with access control lists.

REGULAR CLASSES

Class sessions will be used for

(1) Lectures by the instructor, using powerpoint slides. Interaction with the instructor is expected and encouraged. Students should, as follow-on activity, review and go deeper into the explained topics using the resources in the companion moodle site and in the bibliography.

(2) Some classes will be used to analyze some practical problems provided by the instructor. Students should complete the proposed exercises, which serve as training for the problem-based exams. The student will have available a larger collection of problems to complete as personal work, with orientation and help by the instructor. The moodle platform will be used to facilitate student-student and instructor-student interaction.

(3) A few class sessions will be used to carry out different tests and exams, which are part of the procedures for continuous evaluation of the course



LAB SESSIONS

The practical credits will be completed using a combination of homework using simulators, and lab sessions with actual equipment. A few days before a lab session, the instructor will provide a lab hand-out explaining what is to be done and how, and what is expected to be learned with the activity. As personal work, students will carefully study this hand-out and carry out, at home and using a simulator, the requested activities.



VISITS

Throughout the course we may be visited by network professionals working for large companies, who will talk to us about the networks they work with and their daily activity. We will plan these visits according to the epidemic conditions and the availability of professionals.

• Continuous Assessment System
• Final Assessment System
• Tools and qualification percentages:
  • Written test to be taken (%): 40
  • Multiple-Choice Test (%): 30
  • Realization of Practical Work (exercises, cases or problems) (%): 30

In the first (ordinary) call, all the students must pass the laboratories, by means of two examination sessions to be carried out using simulators.



For the theory and problems parts, students will be allowed to choose between continuous and global evaluation. The default option is continuous evaluation.



Global evaluation: it will be carried out by means of a single test+problems exam to be done at the date scheduled by the Faculty for this purpose. If a student does not take the global exam, it will be understood that he/she waives the ordinary call.



Continuous evaluation: it will be carried out by means of a collection of three multiple-choice tests and two problem exams, taken throughout the course. The last test and the last exam will be taken on the date of the global exam.



Weight of each part: 30% labs, 30% theory tests, 40% problem exams. A minimum of 3.5 points (out of 10) in each part, and an average mark of 5 (out of 10), are required in order to pass the subject.



Students will have the possibility to change from continuous evaluation to global evaluation once they have passed 60% of the evaluated activities. Requests for change will be managed through eGela. Students who do not request the change will remain in continuous evaluation.



In order to waive the ordinary exam, it is compulsory (1) to have requested the change to global evaluation and (2) not to take the final exam.

In the second (extraordinary) call the evaluation mechanism will consist of a global exam with three parts (tests 30%, problems 40%, laboratories 30%). Those students who passed one or more parts in the first call (passing a part means obtaining a minimum of 5 points out of 10 in that part), will be able to skip those parts and keep the corresponding partial grades.



As in the first call, a minimum of 3.5/10 points in each part, and an average grade of 5/10, is required to pass the course. If a student does not take the global exam, it will be understood that he/she waives the extraordinary call.

None of the recommended textbooks can be considered as compulsory. An extensive list of resources is provided for the benefit of the curious students. However, most of the theory lectures, and problems too, will be based on the Kurose & Ross textbook included in the basic bibliography.

Basic bibliography

Computer Networking: A Top-Down Approach, 8th ed. J.F. Kurose and K.W. Ross.

Pearson/Addison-Wesley 2021

Previous editions (7, 6, 5) are perfectly valid options.

In-depth bibliography

We do not consider additional bibliography necessary.

Web addresses

"The TCP/IP guide" electronic book, available for free at http://www.tcpipguide.com/free/index.htm

NetSimK web site: http://netsimk.com
IP calculator: http://jodies.de/ipcalc

Additional resources:
Internet Society tutorials at https://www.internetsociety.org/publications/
Information about assigned names and numbers in the Internet https://www.iana.org/ and http://www.icann.org/resources
Security-related resources from the NIST at http://csrc.nist.gov/publications