Protokoły sieciowe

Revise the information about the tasks of a computer network. Today you will learn how your computer connects to the Internet.

What is a network protocolnetwork protocolnetwork protocol?

A protocol is a set of rules that specify the principles of communication. Over the years many various protocols have been developed, thanks to which different effects can be achieved, e.g.:

• the transmission of files,

• making telephone calls,

• synchronizing the game status in computer games,

• data encryption,

• data compression,

• money transfer.

Most computer applications operate based on the HTTP and HTTPS protocols. All protocols are treated as the stream of bytes by computer equipment and mediation devices and are transmitted to a location where they have been addressed to. Software is responsible for identifying a communication protocol. Computer systems usually do not use one protocol but a set of cooperative protocols which are called the protocol stack.

Data transmissiondata transmissionData transmission is the process of transferring data along a specified way between devices defined in a „language” which is understandable for all devices. More than one recipient can take part in the process. Communication systems communicate between one another by using transmission media. They can be classified as wired and wireless (radio or light waves).

Anyone who begins their education in the field of computer networks must learn the OSI and TCP/IP models and the packets of the TCP/IP protocol. Both models are based on layers. They are an architectural principle dividing that a task into smaller stages. At each stage a specified part of the task is completed, interacting only with the neighbouring layers. This enables to develop cooperative network solutions by different producers for various operating systems.

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Ilustracja przedstawia porównanie modeli TCP/IP i OSI. Grafika podzielona jest na trzy części: po lewej stronie informacje związane z modelem OSI (The OSI Model), po prawej stronie informacje związane z modelem TCP/IP (The TCP/IP Model). Środkową część zajmują pojęcia związane z oboma modelami. W modelu OSI warstwa 1 Phisical (Ethernet cable, fibre, wireless, coax, etc...) oraz warstwa 2 Link (MAC Address, Frame) odpowiadają warstwie Network Access w modelu TCP/IP. W modelu OSI warstwa 3 Network (IP Address: IPv4, IPv5) odpowiada warstwie Internet w modelu TCP/IP. W modelu OSI warstwa 4 Transport (TCP, UDP, Segment) odpowiada warstwie Transport w modelu TCP/IP. W modelu OSI trzy ostatnie warstwy 5 Session, 6 Presentation, 7 Application (DHCP, DNS, FTP, HTTP, HTTPS, POP, SMTP, SSH, etc...) odpowiadają warstwie Application w modelu TCP/IP.

A simplified layerlayerlayer model is divided into three sections:

• media,

• transport,

• applications.

A modemmodemmodem is a network device that modulates a signalsignalsignal in order to encode digital information so that it can be transmitted in a selected transmission medium and demodulates the signal in a receiving device to decode the transmitted data. It is used in point‑to‑point connections. We use modems at home, at school and at work. The modemmodemmodem is the first device your computer, laptop, tablet or telephone connects to when you want to access the Internet.

The types of modems:

• telephone modems,

• xDSL telephone modems,

• cable modems,

• radio modems.

Exercises

Glossary

Keywords

data transmissiondata transmissiondata transmission

layerlayerlayer

network protocolnetwork protocolnetwork protocol

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