COMPUTER NETWORKS

This is a brief introduction to network protocols, we will talk about the ISO/OSI model TCP/IP protocol by examining in detail each layer, the Internet infrastructure, physical means, application layer etc. A network protocol, in telecommunications, is a particular type of communication protocol used to operate a computer network or the formal a priori definition of the methods or rules of interaction that two or more electronic devices connected to each other must comply with in order to operate particular functions processing necessary for the performance of a certain network service. In a broader sense, a communication protocol can [...]

ISO/OSI AND TCP/IP MODEL COMMUNICATION BETWEEN HOST Even on the Internet, communication between Hosts can take place if they all adopt the same standard and the same protocols regardless of the differences. Communication takes place on layers, placed one above the other in a sort of stack or stack. At the lowest level we have the Host to Network level which deals with managing communication on the physical medium. In the upper layer we have another layer that manages other aspects of the connection but still very important and that will implement its own protocols and [...]

THE DEVICES CAN CONNECT TO THE NETWORK VIA RADIO OR BY WIRED MEANS. WIRELESS IEEE 802.11 STANDARD Registered trademark of the Wi-Fi Alliance group dedicated to certifying that Wi-Fi products comply with IEEE 802.11 wireless standards. Each new standard improves performance, reliability and safety. The hardware must be manufactured specifically to support a standard. WIRED NETWORK STANDARD IEEE 802.3 (ETHERNET): Speeds from 10 to 1000 Mbps on various physical media (coaxial, twisted pairs and optical fibers) Comparative table of the most popular 802.3 standards: The most commonly used are 100Base-TX (Fast Ethernet) which [...]

METHOD OF TRANSMISSION There are three ways: Unicast when there is a sender and a recipient; Multicast when sending a message from one sender to multiple recipients; Broadcast when a sender sends a message to all recipients for example in a WhatsApp group chat. UNICAST This connection mode creates contact only between interested parties. It does not matter whether the transfer is bidirectional or not: it does not matter if the recipient becomes the sender, giving rise to a bidirectional exchange of data, or if the connection remains unidirectional. As long as there is a flow of information between [...]

PHYSICAL LEVEL AND DATALINK PHYSICAL LEVEL In telecommunications in the context of computer networks, the physical layer is level 1 of the ISO/OSI model. In transmission, this layer receives from the datalink layer the packetized bit sequence to be transmitted on the channel and converts it into signals suitable for the transmission medium such as coaxial cable (BNC connector), STP or UTP twisted pair, optical fibers or radio waves. In particular, a physical layer standard defines: the physical characteristics of the transmission medium such as shape, size, number of pins of a connector and mechanical specifications; functional characteristics such [...]

RESIDENTIAL ACCESS ISP (Internet Service Provider) Residential access simply means how the Internet reaches our homes. In practice it is a PTP (Point-to-Point) connection between the ISP (Vodafone, Tim, Fastweb etc.) and the customer. The Internet Service Provider allows us to access a much wider network, the Internet, which we will see later. The most common access modes were Dial-Up, ISDN to get to the present day with: XDLS xDSL (Digital Subscriber Line) which is a family of technologies that allow you to use the copper twisted pair at the same time for both digital data and analog telephone [...]

NETWORK LEVEL In telecommunications and information technology in the context of computer networks, the network layer is level 3 of the ISO / OSI stack. This layer receives segments from the above transport layer and forms packets which are passed to the underlying data link layer. The task of the network layer is the logical transmission of packets between two arbitrary hosts, which in general are not directly connected (that is, they do not have a direct connection between them), i.e. essentially it deals with addressing and routing to the right destination through the most appropriate network path. NETWORK [...]

TRANSPORT LEVEL The transport layer, in telecommunications, information technology and in the field of computer networks, is the fourth of the layers in the ISO/OSI model. Its task is to provide services to the above level Application of the TCP/IP model and to achieve this it uses the services offered by the underlying level 3 (network level). The purpose of the transport layer is to provide an end-to-end logical communication channel for packets, essentially providing logical communication between application processes of different hosts. FUNCTIONALITY The following are the services that are generally offered by the transport [...]

In telecommunications, the application layer is the seventh and last layer of the ISO / OSI model for computer networks. Its function is to interface and provide services for application processes; in transmission, therefore, it forwards the requests to the underlying presentation level, while in reception it receives them. An application program interacts with one of the transport layer protocols to receive data or send it by passing it in the required form. Among the most common services offered by the application layer are semantic conversions between associated application processes. DYNAMIC HOST CONFIGURATION PROTOCOL In telecommunications and IT, the [...]

HOSTNAME AND IP ADDRESSES If I want to visit Google I will not write in the browser 216.58.205.78 but simply google.com. This can happen because a binding has been made between the Google IP and the name google.com. LOCAL TRANSLATION You can enter IP associations: Name manually in the hosts.txt (Windows) and /etc/hosts (Linux and MacOS) files: THE DNS In computer science and telecommunications, the Domain Name System  is a system used to assign names to network nodes (in English: hosts). These names can be used, by means of a translation, usually called "resolution", in place [...]