Related topics: Wireless networks
A network consists of a set of computers or processing systems connected to each other through appropriate communication channels. Networks offer services obtained by integrating computer technologies and telecommunications to share resources, communicate, provide interactive entertainment, access remote information, and engage in various forms of electronic commerce. Networks can also be used to implement distributed computing systems.
Networks can be classified based on various criteria, including transmission technology, scale, architecture, topology, and transmission media.
The criteria of transmission technology and scale, which refers to the physical distance between connected processors in a network, represent the primary method of classification. In addition to these classifications, there are often mentions of public networks with technologies such as PSNT, ISDN, ADSL, FTTS, FTTH, PON, and GPON, as well as broadband networks, cellular networks, and satellite networks.
Classification based on transmission technology
The main transmission technologies used in computer networks are broadcast and point-to-point. Hence, we can talk about broadcast networks and point-to-point networks.
In broadcast networks, there is a single shared communication channel for all network resources. Packets are sent by each machine and received by all others, but only the machine that recognizes its address will process it, while the other machines, although listening, will ignore it.
In broadcast networks, there are two operational transmission modes: broadcasting and multicasting, although the latter is not always supported.
In broadcasting mode, packets are transmitted by specifying a special code in the address field that allows all listening machines on the network to recognize and process those packets.
In multicasting mode, the packet can be sent to a subset of machines on the network through a similar mechanism that uses one bit to specify multicasting and the remaining (n-1) bits to identify the group.
In point-to-point networks, connections occur between pairs of machines. In this type of network, it is important to choose the best path, which may involve multiple paths, to deliver packets from the source to the destination.
Unicast communication is used in point-to-point transmissions, where there is a transmitter and a receiver.
Classification based on scale
Networks classified based on scale or size use criteria such as the physical distance between processors and the surface area as classification factors.
Personal Area Network
These are networks where processors have a distance of up to 1 meter, and the maximum surface area is 1 square meter.
Local Area Networks (LAN)
Local Area Networks, or LANs, are small-sized networks corresponding to the surface area of a room, a building, or a campus. The physical distance between processors is typically 10m, 100m, or 1km. Examples of LANs include school computer labs, classrooms, and the computer systems of companies or corporate structures composed of adjacent buildings. The small size of these networks allows for high communication speeds.
Metropolitan Area Network (MAN)
Metropolitan Area Networks, or MANs, are characterized by a physical distance between processors of up to 10km and cover the area of a city.
Wide Area Networks (WAN)
Wide Area Networks, or WANs, are large-scale networks with a physical distance between processors ranging from 100km to 1000km, covering the territory of a nation or a continent. The implementation of this type of network typically relies on existing infrastructures such as public networks and the internet. Dedicated geographic networks are used by large companies and organizations to ensure better protection of their information systems.
The internet is a worldwide extended network with a processor distance of at least 10,000km.
Classification based on architecture
In the client/server architecture, computers that host programs providing services are called servers. Servers offer their services to other programs running on different computers, even if they can both be hosted on the same machine. Sometimes a program can simultaneously act as both a server and a client, blurring the distinction within the architecture.
Peer to Peer
In peer-to-peer networks, each computer functions as both a client and a server, offering shared resources to the entire network. These shared resources include mass storage such as hard disks and optical disks, as well as hardware and software resources. This network architecture is typically used when there is no need for administrative units or user access control with identification.
Classification based on transmission medium
This classification is based on the physical medium used to connect computer systems, including connectors, copper or fiber optic cables, and radio signals in the case of wireless installations.
The transmission medium consists of a thin glass wire through which light pulses travel from one end to the other.
Electrical signals are converted into light pulses by a modulator, then routed and transmitted at speeds close to that of light to the other end of the fiber, where the light signal is converted back into an electrical signal. The achieved speeds are in the order of Gbps, depending on the type of fiber optic and the technology used. Fiber optics are suitable for creating backbones for interconnecting networks and establishing data lines within cities. They are replacing UTP cables in telephone networks and LAN cabling, offering broadband capabilities at higher speeds with limited signal attenuation and dispersion.
Wireless networks utilize radio signals as the transmission medium, allowing for easy network creation without the need for any wiring. The IEEE 802.11 standard and its subsequent versions are the reference standards for wireless networks.