COMPUTER NETWORKS

Computer networks are an integral part of ICT systems, and are massively pervasive. It is essential that students have a thorough understanding of how they work and how they affect the performance of the software that is used at the application levels. Knowledge of how networks work is key both for those who want to pursue a career as a systems administrator, but also for developers who need to know how the network introduces delays, congestion, and exposes private information to third parties.

The course is divided in two, a first half about algorithms, communication fundamentals and security, a second about network protocols.

The student will achieve the following knowledge:
- network architectures and network stacks
- the challenges related to each layer of the network stack
- the way protocols are designed to address these challenges

The student will achieve the following skills:
- interpret traffic flows in a network, how to scale the network components.
- design a basic network architecture with address assignment and routing tables
- use known tools and primitives to create simple services

The student will obtain the following judgment and communication skills:
- interpret a network architecture proposal, evaluating its soundness, the presence of essential services, the security of the system components
- Communicate specific component and service support needs when dealing with industry experts and service suppliers.

Familiarity with C language provided by the coding exam.

Part 1: principles and algorithms.
- Packet Switching and Network Stack models
- Physical Layer: elements of the physics of communication, Nyquist and Shannon theorems
- Datalink Layer: parity, checksum, go-back-n, selective repeat. Network topologies, time-division and random access
- Network Layer: datagrams, addresses, distance vector and link-state routing
- Transport and Application layers: services, connectionless/connection-oriented, naming principles
- Security services and cryptography: Hash functions, Symmetric key cryptography, HMAC, public key cryptography, certificates

Part 2: Protocols implementing the principles (top-Down)
- The application Layer: DNS, SMTP, POP, e-mail Security Extensions, HTML, HTTP
- The Transport Layer: UDP, TCP
- The Network Layer: IPv4, routing tables, ICMP, OSPF, essentials of BGP
- The Data Link Layer: Ethernet, ARP, DHCP, 802.11, Spanning Tree
- Extra, socket programming and secure protocols: TLS

Recommended book:
O. Bonaventure, "Computer Networking : Principles, Protocols and Practice" third edition. Freely available on-line.
A.Tanenbaum, D. Wetherall, ‘Reti di Calcolatori’, 6yh edition, Pearson.

The exam consists of two written tests, which take place sequentially on the same day using the Moodle platform (in the lab), and an optional oral exam.

A first written test with multiple-choice questions (50% of the grade), a second written test with open-ended questions (50% of the grade).
The exam can be passed (even with the maximum score) based on the written tests alone; students who have obtained a grade higher than 24 may choose to take an oral exam to increase the obtained score.

The test consists of exercises that assess the acquired knowledge:
- principles underlying network communications
- essential components of existing network protocols
- the security characteristics of protocols

The exercises will also have to verify the skills:
- analyzing the performance of a network system
- verifying the correctness of a network system
- verifying the security characteristics of a network system

Finally, through the verification of language proficiency, the correct use of terminology, and familiarity with the use of some basic commands, judgment and communication skills will be assessed, to ensure that the student has developed not only practical and theoretical knowledge but also the ability to formulate problems and solutions using the correct technical language.

written and oral

The exam grading is formulated as follows:
18: The student is familiar with essential communication concepts, the basic characteristics of individual protocols, and estimating their performance.
19-25: The student demonstrates the ability to place principles and protocols within the context of a network architecture, explaining the interactions between components and summarizing the problems that each component solves.
25-30: The student demonstrates the ability to solve more advanced network design problems, which require greater detail and greater interactions between components.

Frontal course which also makes use of teaching modules available on the university e-learning platform moodle.unive.it and other platforms for the creation of online exercises.
The lessons will have a theoretical component and some exercises. If possible, extra activities will be proposed such as group exercises in the classroom, or presentations on topics chosen by the students.