Computer Networks


Educational goals

The aim of the course is to introduce the student to the basic principles of the TCP / IP protocols and to issues related to the specifications and the provision of Internet services. Sub-objectives of the course are (a) knowledge of Internet addressing (b) calculation of station addresses using sub-networking and over-networking procedures (c) knowledge of Internet reporting and error correction procedures using the ICMP protocol (d) understanding of problems that arise in the process of transferring information packets end-to-end (e) knowledge of the procedures of the IP network protocol that achieve the transfer of information packets end-to-end (f) understanding of transport layer services problems (g) knowledge of the procedures of the TCP and UDP transfer protocols and (h) an understanding of the most important internet applications (electronic mail, FTP, World-Wide-Web, etc.)

  • Indicate Internet addressing procedures for successful and efficient communication of connected Internet stations
  • Evaluate the importance of TCP / IP model
  • Distinguish the functionality of Link layer and Network layer addressing
  • Report the problems that arise during the implementation of the IP Network protocol and the TCP and UDP transfer protocols
  • Indicate the procedures implemented by the IP protocol for successful packet transfer over the Internet
  • Evaluate the performance of IP Network protocol procedures compared to alternative protocols
  • Distinguish the important decisions taken in the design of network layer and transport layer protocols for efficient computer communication over the Internet
General Skills
  • Practical training in the laboratory
  • Autonomous work for the elaboration of the laboratory exercises
  • Search for information on the internet

Course Contents

Introduction: Internetworking, open system interconnection, Internet services and applications, historical data.

Protocol layering: Layering principle, ISO reference model, X.25 protocol, TCP / IP reference model.

Architectural modeling Internetworking: Interconnectiong application and network levels, properties and architecture of the Internet.

Internet addressing: Classful addressing model, subnetting and supernetting, special IP addresses (directed broadcast, restricted broadcast, return loop).

Address Resolution Protocol (ARP): Converting IP addresses to physical addresses, direct mapping, dynamic assignment, cache, ARP enhancements, ARP implementation, ARP message format, Reverse Address Resolution Protocol (RARP).

Internet Protocol (IP): Connectionless packet delivery system, purpose of the IP protocol, standalone IP packet format, IP packet header fields, packet segmentation and reassembly, Time-To-Live, IP packet options (record route, loose and strict source routing), routing of standalone IP packets (direct and indirect delivery, next hop routing).

ICMP protocol: Error reporting and correction, ICMP message delivery, ICMP message format, ping command, congestion, source suppression.

Internet Routing: Static and Dynamic Routing, the Concept of Autonomous Systems, Metric and Routing Performance, Routing Tables, Routing Algorithms (Short Path, Flooded, Distance Vector, Link State), Routing Information Protocol (RIP), Open Shortest Path First (OSPF) protocol, Border Gate Protocol (BGP).

User Datagram Protocol (UDP): Definition of final destination, UDP message format, UDP encapsulation and layering, multiplexing / demultiplexing, UDP ports.

Transmission Control Protocol (TCP): Reliable data stream service, properties, sliding windows, TCP ports, passive / active opening functions, sequence numbers, variable window size and flow control, TCP header format, maximum segment size TCP, acknowledgements, timeout and retransmission time, Round Trip Time, congestion control (congestion window, congestion avoidance with multiplicative decrease, slow start, queue drop, random early drop), silly window syndrome, delayed acknowledgements.

Domain Name System (DNS) Naming: Internet domain names, hierarchy and domain name server architectures, performance optimization, domain name shortening.

Internet services and applications: E-mail. File transfer and access. Worldwide web. Teleconnection. Internet Telephony.

Teaching Methods - Evaluation

Teaching Method
  • Face to face theoretical teaching (lecture, discussion, problem solving).
  • Face to face teaching in the laboratory (lecture, discussion, problem solving).
Use of ICT means
  • Use of the educational version of the RIVERBED simulator to analyze the efficiency of networks and directly examine the efficiency of alternative network proposals.
  • Use of Wireshark Computer Network Protocol Analysis Software for the process of encapsulating and disencapsulating information.
  • Support of the learning process through the electronic platform Moodle
Teaching Organization
Activity Semester workload
Laboratory exercises26
Preparation for laboratory exercises26
Individual study and analysis of literature76
Total 180
Students evaluation

Ι. Written final exam (60%) in the theoretical part of the course which includes:
- Exercises concerning the architecture of the TCP / IP model, the operation and improvements of the ARP protocol, the Internet routing protocols and the naming using the domain name system
- Subnetting process in real conditions with variable size masks
- Exercises in Internet services and applications
- IP protocol queries that include the functionality of the IP packet header fields, packet segmentation and reassembly procedures, and the IP packet option fields.
- Questions including the Transmission Control Protocol (TCP) functionality, sliding window procedure, TCP ports, active / passive opening functions, flow control, and congestion window.

ΙΙ. Practice in the laboratory (40%)

- Exercises for practical training, on weekly basis
- Final exam in the laboratory part of the course with exercises (a) in the educational version of the RIVERBED simulator in Ethernet, IP protocols and packet routing and (b) exercises in the Wireshark computer network protocol analysis software on the process of encapsulation and disencapsulation of information.

The above assessment scheme in the theoretical and laboratory parts of the course is communicated to the interested students (a) through the website of the department, (b) through the pages of the course on the Moodle electronic platform, and (c) with announcements during the first lecture and meeting in the laboratory at the beginning of each academic semester.

Recommended Bibliography

Recommended Bibliography through "Eudoxus"
  1. Book [77106973]: Computer Networking, 7th Edition, James F. Kurose, Keith W. Ross
  2. Book [13637]: Internetworking with TCP/IP Vol. 1: Principles, Protocols, and Architecture, 4th Edition DOUGLAS E. COMER
Complementary greek bibliography
  1. Larry L. Peterson, Bruce S. Davie, “Computer Networks: A Systems Approach”,4η american edition, Klidarithmos Publications.
  2. Emad Aboelela, “Network Simulation Exercises”, Klidarithmos Publications, 2010.
  3. S. Tanenbaum, “Computer Networks”, 5th american edition, Klidarithmos Publications, 2010.
  4. Α. Alexopoulos and G. Lagogiannis, “Telecommunications and Computer Networks”, 10th Edition, 2016.
Complementary international bibliography
  1. Douglas E. Comer, Internetworking with TCP/IP, 6th Edition, Addison-Wesley, 2013
  2. Douglas E. Comer, Computer Networks and Internets, 6th Edition, Addison-Wesley, 2014
  3. James F. Kurose, Keith W. Ross, Computer Networking: A Top-Down Approach, 6th Edition, Pearson, 2012
  4. Larry L. Peterson, Bruce S. Davie, Computer Networks, Fifth Edition: A Systems Approach, The Morgan Kaufmann Series in Networking, 2011.
  5. Emad Aboelela, Network Simulation Experiments Manual, 5th Edition, The Morgan Kaufmann Series in Networking, 2011.
  6. Andrew S. Tanenbaum, David J. Wetherall, Computer Networks, 5th Edition, Prentice Hall, 2010
Scientific journals
  1. IEEE Communications Magazine
  2. IEEE Transaction on Communications
  3. IEEE Communications Surveys & Tutorials