8. Specify End devices, data transfer devices, transmission medium.

A computer network is a collection of computers and devices connected via communication devices and transmission media.

The main purpose of the network - a convenient and fast data exchange (of information) between devices.

Network components:

- End Devices

- Intermediary Devices

- Network Media.

The network devices that people are most familiar with are called end devices. These devices form the interface between the human network and the underlying communication network. Some examples of end devices are:

• Computers (work stations, laptops, file servers, web servers)

• Network printers

• VoIP phones

• Security cameras

Mobile handheld devices (such as wireless barcode scanners, PDAs

• Intermediary Devices network component or intermediate device is such a device that combine endpoints in local (or global) data network.

For intermediate devices include hubs (hubs), switches (switches, switches), routers (routers, routers), modems (modems), wireless access point (Wireless Access Point) and firewalls (firewalls, brendmauers).

Network Media - is a metal wire (copper twisted pair telephone cable), glass (glass), or even "air” (Bluetooth, Wi-Fi, 3G, LTE). By "air" shall mean the data transmission medium without wires, that is "wireless."

• When we go to the website, we (or rather, our browser) first sends a request to a web server where you store the files of the requested site, and have a special service (program the HTTP server) processes the request and sends us back the web page file which (web page) and we will see in the browser.

Services: Web server, mail-server, ftp-server.

Processes, unlike services are invisible to us, but they (the process) is much more important for us and our network. This process works day and night on the routers, switches, wireless access points and other network equipment.

Processes: special service network processes running on network equipment.

Local-area network (LAN)A network that connects a relatively small number of machines in a relatively close geographical area

Types of Networks

Various configurations, called topologies, have been used to administer LANs

• Ring topology A configuration that connects all nodes in a closed loop on which messages travel in one direction

• Star topology A configuration that centers around one node to which all others are connected and through which all messages are sent

• Bus topology All nodes are connected to a single communication line that carries messages in both directions

• Wide-area network (WAN) A network that connects two or more local-area networks over a potentially large geographic distance

Often one particular node on a LAN is set up to serve as a gateway to handle all communication going between that LAN and other networks

Communication between networks is called internetworking

The Internet, as we know it today, is essentially the ultimate wide-area network, spanning the entire globe

• Metropolitan-area network (MAN) The communication infrastructures that have been developed in and around large cities