4.2 THE BASICS OF NETWORKS 82 With a basic hub, the speed of the network is defined by the slowest network card connected. Ethernet is the traditional technology for connecting devices in a wired local area network (LAN). Can you name at least three ISPs? Do you remember what the main function of an operating system is? ONLINE RESOURCES Communication protocols: the ISO/OSI model amount: quantità suitable: adatto NETWORKS AND THEIR COMPONENTS What is a computer network? A computer network refers to a set of interconnected computers that can share resources, data and an Internet connection with each other. These computers use a system of rules called communication protocol that enables them to transmit data and information over physical or wireless technologies. Networks may be classified according to the way they operate into peer-to-peer or client server. Peer-to-peer networks Client-server networks All the computers have equal status. All the computers can share each other s resources. They are only suitable for small networks. As more people use the network, the whole network slows down. One more powerful computer (the server) is used to store the data and programs needed by the whole network. The network is totally dependent on the server; if this breaks down, the network cannot be used. They are the popular choice for networks that need many computers. Network components The components of a network can be grouped into two categories: hardware and software components. Hardware components Server: a powerful computer that stores data or applications and connects to resources that are shared by the users of a network. Client: the computer used by the users of the network to access the servers and shared resources (such as hard disks and printers), e.g. a workstation. Interface devices: the devices that connect clients and servers to the channel, e.g. modems and network interface cards (NIC). Hub : a small device used to connect multiple devices in a network. The common standard for hardware connectivity is ethernet . Switch: similar to the hub but it divides the network into independent segments which reduce the amount of data travelling. Router: a device which works as the central point between computers and wired or wireless networks and that manages communication traffic. Modem: a device that connects a home network to the Internet service provider, or ISP, which is a company that provides access to the internet . - Gateway: a device that connects networks belonging to different networking types. Software components Operating system : it enables computers connected by a network to exchange data, programs, peripherals, etc., and is usually installed on the server. Protocol suite: a set of rules and guidelines that are followed by each computer in the network for data communication. Nowadays, the most commonly used is TCP/ IP, which is the protocol for communication between computers on the Internet. 186 TelecoMMUNicaTioNs aND NeTWorKs Elettronica-Informatica.indb 186 25/01/24 16:09