A Computer Network defines a set of computer devices that share resources located on or provided by network nodes. The computers communicate with one another through standard communication protocols over digital connections. These connections are composed of telecommunication network technologies based on optical, physically wired, and wireless radio-frequency technologies and may be set up in several different network topologies. 

Personal computers, servers, networking equipment, and other specialized or general-purpose hosts can all function as nodes in a computer network. They can have hostnames and are identifiable by network addresses. After being assigned, hostnames act as recognizable labels for the nodes and are rarely updated. Communication protocols like the Internet Protocol use network address to locate and identify the nodes. Computer networks can be categorized using a variety of factors, including the signal transmission medium, bandwidth, communications protocols used to organize network size, network traffic, topology, traffic management system, and organizational goals. Computer networks allow users to access the World Wide Web, stream digital video and audio, share printers, fax machines, and application and storage servers, and use email and instant messaging software.

Communication Protocols

A communication protocol defines a set of rules governing data exchange through a network. Different communication protocols have different properties, and they can employ circuit mode or packet switching, be connection-oriented or connectionless, and have flat or hierarchical addressing.

A protocol stack is frequently built in accordance with the OSI model and divides communications functions into protocol layers. Each layer uses the services of the next layer until the lowest layer is in charge of the hardware that transmits data across the media. Protocol layering is widely used in computer networking. The World Wide Web protocol HTTP running over TCP over IP (the Internet protocols) over the WiFi protocol is a prime illustration of a protocol stack. When a user is browsing the internet at home, this stack is employed between the wireless router and the user's PC.

Computer Networking Protocols

• Internet Protocol Suite

The core of all contemporary networking is the Internet Protocol Suite, generally known as TCP/IP. Over a network that is intrinsically unreliable and is traversed by datagram transmission utilizing the Internet protocol, it provides connection-less and connection-oriented services (IP). The protocol's successor with significantly expanded addressing capabilities, the protocol suite's key specifications include addressing, identity, and routing for Internet Protocol Version 4 (IPv4) and IPv6. The Internet Protocol Suite is the Internet's defining set of protocols.

• Ethernet

Wired LANs employ the Ethernet family of technologies. 

• IEEE 802

A group of IEEE standards known as IEEE 802 deal with metropolitan and local area networks. The complete IEEE 802 protocol suite offers a broad range of networking capabilities. The addressing method used by the protocols is flat, and the OSI model's layers 1 and 2 are where they primarily function.

For instance, MAC bridging (IEEE 802.1D) deals with the Spanning Tree Protocol-based routing of Ethernet packets. In WLANs, it is what the home user sees when they have to enter a "wireless access key." IEEE 802.1X is a port-based Network Access Control protocol that serves as the foundation for the authentication procedures used in VLANs.

• Wireless LAN

The most popular component of the IEEE 802 protocol suite for home users is wireless LAN based on the IEEE 802.11 specifications, popularly known as WLAN or WiFi. Wired Ethernet and IEEE 802.11 have many similar characteristics.

• SONET/SDH

Standardized multiplexing systems like Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) use lasers to transmit multiple digital bit streams via optical fiber. They were initially created to facilitate circuit-switched digital telephony and convey circuit-mode communications from various sources. However, SONET/SDH was also the clear choice for transmitting Asynchronous Transfer Mode (ATM) frames based on its protocol neutrality and transport-oriented capabilities.

• Asynchronous Transfer Mode

Asynchronous Transfer Mode (ATM) is a switching method in communication networks. Data is encoded into tiny, fixed-sized cells using asynchronous time-division multiplexing. This contrasts with other protocols that use variable-sized packets or frames, like Ethernet or the Internet Protocol Suite. Circuit-switched networking and packet-switched networking are comparable to ATM. This makes it a wise choice for a network that manages conventional high-throughput data traffic and real-time, low-latency content like voice and video. In the connection-oriented approach used by ATM, a virtual circuit between two endpoints must be formed before the actual data transmission can start. ATMs continue to play a role in the final stage, or the link between an Internet service provider and the home user.

• Cellular Standards

Global System for Mobile Communications (GSM), CDMA2000, cdmaOne, Evolution-Data Optimized (EV-DO), General Packet Radio Service (GPRS), Enhanced Data Rates for GSM Evolution (EDGE), Digital Enhanced Cordless Telecommunications (DECT), Universal Mobile Telecommunications System (UMTS), Digital AMPS (IS-136/TDMA), and Integrated Digital Enhanced Network are a few examples of the various digital cellular standards (iDEN).

Routing

Routing is the process of choosing network routes for the conveyance of network traffic. Routing is used in various networks, including circuit-switching and packet-switched networks.

Routing protocols in packet-switched networks direct packet forwarding through intermediary nodes. Typically, intermediate nodes include switches, routers, bridges, gateways, firewalls, or other types of network infrastructure. Although they may have limited performance due to the absence of specialized hardware, general-purpose computers can also forward packets and conduct routing.
The routing procedure controls forwarding based on routing tables, which keep track of the routes to different network destinations. Routing algorithms typically use one network path at a time, and multiple alternative paths can be employed for multipath routing algorithms. 

In contrast to bridging, routing assumes that network addresses are organized, and comparable addresses indicate close proximity inside the network. Structured addresses make it possible to define the path to a collection of devices in a single routing table entry. Structured addressing, which routers employ, performs better in extensive networks than unstructured addressing, which bridging uses. The Internet uses structured IP addresses. On Ethernet and other local area networks, bridging is performed using unstructured MAC addresses.

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