Introduction to computer networks. Basic concepts of networking. The most important applications of computer networks. Network software: protocol hierarchy, the relationship of protocols and services, connection-oriented and connectionless services. The OSI reference model. The TCP/IP reference model. Comparison of the OSI reference model to TCP/IP. Individually, on layers of the OSI model. Application layer: DNS - domain name service; E-mail: architecture and service, formats and transfer of messages; WWW - world wide web: architecture, static and dynamic web files; HTTP; FTP - file transfer protocol. The transport layer: Transport-layer services. TCP and UDP protocol. Network layer. Services of the network layer: Virtual circuits and datagram circuits. Routing algorithms. Algorithms for controlling congestion. IP protocol. Medium access layer: the problem of channel allocation and multiple access to networks. The most important protocols for multiple access control: ALOHA protocol with carrier sense protocols for collision avoidance, WLAN protocols. Ethernet: cabling system, Ethernet features, Switched Ethernet, Fast Ethernet, Gigabit Ethernet. Error detection and error correction codes. Other protocols of the data transfer layer. HDLC. PPP.