What is a computer network

What Is Computer Networking?

The basics of networking and its uses

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Computer networking, not to be confused with social networking, is the practice of interfacing two or more computing devices for the purpose of sharing data. Computer networks are built with a combination of hardware and software.

Computer Network Classification and Area Networks

Computer networks can be categorized in several ways. One approach defines the type of network according to the geographic area it spans. Local area networks (LANs), for example, typically span a single home, school, or small office building, whereas wide area networks (WANs), reach across cities, states, or even the entire world. The internet is the world’s largest public WAN.

Network Design

Computer networks also differ in their design approach. The two basic forms of network design are called client-server and peer-to-peer.

Client-server networks feature centralized server computers that store email, web pages, files, and applications accessed by client computers and other client devices. On a peer-to-peer network, conversely, all devices tend to support the same functions. Client-server networks are common in business, and peer-to-peer networks are common in homes.

A network topology defines the network layout or structure from the point of view of data flow. In bus networks, for example, all computers share and communicate across one common conduit, whereas in a star network, data flows through one centralized device. Common types of network topologies include bus, star, ring, and mesh.

Network Protocols

Communication languages used by computer devices are called network protocols. Another way to classify computer networks is by the set of protocols they support. Networks often implement multiple protocols and each network supports specific applications. Popular protocols include TCP/IP—the one commonly found on the internet and in home networks.

Computer Network Hardware and Software

Special purpose communication devices (including network routers, access points, and network cables) physically glue a network together. Network operating systems and other software applications generate network traffic and enable users to do useful things.

computer network

A computer network, also referred to as a data network, is a series of interconnected nodes that can transmit, receive and exchange data, voice and video traffic. Examples of nodes in a network include servers or modems. Computer networks commonly help endpoint users share resources and communicate. They commonly appear all over the place, such as homes, offices and government administrations. The use of computer networks can overcome geographic barriers and enable the sharing of information. Computer networks enable the usage and sharing of any number of applications and services, including emails, video, audio and plenty of other types of data, over the internet.

Network devices use a variety of protocols and algorithms to specify exactly how endpoints should transmit and receive data. For example, the Ethernet standard establishes a common language for wired networks to communicate, and the 802.11 standard does the same for wireless local area networks (WLANs).

Computer networks have a variety of uses that many would see as essential today, including the following:

In addition, program design requires skills and knowledge in both computer network technologies and program requirements.

Computer networks operate using a varying set of hardware and software. All packet-switched networks use Transmission Control Protocol/Internet Protocol (TCP/IP) to establish a standard means of communication. Each endpoint in a network has a unique identifier that is used to indicate the source or destination of the transmission. Identifiers include the node’s IP address or Media Access Control (MAC) address. Endpoint nodes, which are used for routing purposes, include switches and routers, servers, personal computers, phones, networked printers and other peripheral computing devices, as well as sensors and actuators. The Open Systems Interconnection (OSI) model defines how data is transferred between computers.

A network’s capacity is how much traffic the network can support at any one time while still meeting service-level agreements (SLAs). Network capacity is measured in terms of bandwidth. Bandwidth is quantified by the theoretical maximum number of bits per second (bps) that can pass through a network device. Throughput is a measure of the actual speed of a successful transmission after accounting for factors like latency, processing power and protocol overhead.

Advantages of using computer networks include the following:

Networks are often categorized by the wired or wireless transmission technology they support, as well as the scope of their domains. Some examples of computer networks include the following:

Networks may also be divided into subnetworks, also called subnets.

Networks can be public or private. While anyone can access the public internet, access to private and virtually private networks requires the end user to be assigned access credentials.

In the enterprise, network access control (NAC) systems typically use security policies to control access to the organization’s network. This means that network devices are not allowed to connect unless they meet a predefined business policy, which is enforced by NAC products. When deployed, NAC systems immediately discover all the devices connected to a network, categorize them by type and then react to them based on preconfigured compliance rules implemented by the organization’s security team.

NAC products enable device access to a network based on a specific, per-device basis, with granular controls over what type and level of access is allowed. These controls are delivered by policies that are defined in a central control system. Most NAC systems can also integrate with Active Directory (AD) in order to control network access based on group policy, ensuring users only have the network access required to fulfill their jobs.

A network topology is the physical or logical structure of a network. Network topologies include the following:

Network topologies are the physical or logical structure of a network. The term network fabric describes the way each topology creates a particular type of crisscross pattern of connections, such as bus, ring and star topologies. The word fabric is used as an allusion to threads in a fabric. A good way to remember the difference is that network fabrics describe a network topology.

Related Terms

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6 types of enterprise networking topologies

network node

network topology

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What is Computer Networking?

A computer network is a system that connects numerous independent computers in order to share information (data) and resources. The integration of computers and other different devices allows users to communicate more easily.
A computer network is a collection of two or more computer systems that are linked together. A network connection can be established using either cable or wireless media. Hardware and software are used to connect computers and tools in any network.
A computer network consists of various kinds of nodes. Servers, networking hardware, personal computers, and other specialized or general-purpose hosts can all be nodes in a computer network. Hostnames and network addresses are used to identify them.

Criteria of good network:

Goal Of Networking:

Types of Networks

Division based on the communication medium

Division based on area covered

Point To Point: Connects two connecting devices through transmission media.

Switched: A switched WAN is a network with more than two ends.

Based on types of communication

Based on the type of architecture

Network Topology

1. Bus Topology: Every computer and network device is connected to a single cable in a bus topology network. Linear Bus topology is defined as having exactly two terminals.

Advantages

Disadvantages

2. Ring Topology: The topology is named ring topology because one computer is connected to another, with the final one being connected to the first. Exactly two neighbors for each device. A signal is passed along the ring in one direction. Each ring incorporates a repeater.

Advantages

Disadvantages

3. Star Topology: Each device in a star topology has a dedicated point-to-point link to a central controller, which is commonly referred to as the HUB. There is no direct connection between the devices. Traffic between the devices is not allowed in this topology. As an exchange, the controller is used.

Advantages

Disadvantages

Example: Used in high-speed LANs

4. Mesh Topology: Every device in a mesh topology has dedicated point-to-point connectivity to every other device. The term “dedicated” refers to the fact that the link exclusively transports data between the two devices it links. To connect n devices, a fully connected mesh network contains n *(n-1)/2 physical channels.

Advantages

Disadvantages

Example: connection of telephone regional office in which each regional office needs to be connected to every other regional office.

5. Tree Topology: The topology of a tree is similar to that of a star. Nodes in a tree, like those in a star, are connected to a central hub that manages network traffic. It has a root node, which is connected to all other nodes, producing a hierarchy. Hierarchical topology is another name for it. The number of Star networks is connected via Bus in Tree Topology.

Advantages

Disadvantages

Networking Devices

Basic hardware interconnecting network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers, are used in all networks. In addition, a mechanism for connecting these building parts is necessary, which is usually galvanic cable and optical cable are less popular (“optical fiber”)The following are the network devices :

Internet

The internet is a larger network that allows computer networks controlled by enterprises, governments, colleges, and other organizations all over the world to communicate with one another. As a result, there are a tangle of cables, computers, data centers, routers, servers, repeaters, satellites, and wi-fi towers that allow digital data to go around the world.

The Internet is a vast network of networks that functions as a networking infrastructure. It links millions of computers throughout the world, creating a network in which any computer can talk with any other computer as long as they are both linked to the Internet.

The Internet is a global network of interconnected computers that communicate and share information using a standardized Internet Protocol Suite.

Sample Questions

Question 1: List the advantages and disadvantages of the internet.

Solution:

Disadvantages of internet are,

Question 2: List the ways to connect to the internet.

Solution:

We can connect to the internet in the following ways:

Question 3: Compare the Internet & the World Wide Web

Solution:

Sir Tim Berners-Lee is credited with creating the World Wide Web. He came up with the core idea for the WWW while working at the European Organization for Nuclear Research in 1989. He wanted to combine the growing technologies of computers, data networks, and hypertext into a powerful and easy-to-use worldwide information system.

The Internet is a vast network of networks that functions as a networking infrastructure. It links millions of computers throughout the world, creating a network in which any computer can talk with any other computer as long as they are both linked to the Internet. The World Wide Web, or simply Web, is a method of gaining access to information over the Internet.

The World Wide Web, also known as the ‘www,’ is a collection of webpages that can be quickly published on the Internet and read by millions of people.

Question 4: What is the full form of www?

Solution:

The full form of www is World Wide Web. It is the world’s most dominant software and is commonly known as the web.

Question 5: What is the basic difference between the Internet and the network?

What is a Computer Network?

Computer networks are the basis of communication in IT. They are used in a huge variety of ways and can include many different types of network. A computer network is a set of computers that are connected together so that they can share information. The earliest examples of computer networks are from the 1960s, but they have come a long way in the half-century since then.

What Do Networks Do?

Computer networks are used to carry out a large number of tasks through the sharing of information.

Some of the things that networks are used for include:

Types of Network

There are many different types of network, which can be used for different purposes and by different types of people and organization. Here are some of the network types that you might come across:

Network Design

Computer networks can have different designs, with the two basic forms being client/server and peer-to-peer networks. Client/server networks have centralized servers for storage, which are accessed by client computers and devices. Peer-to-peer networks tend to have devices that support the same functions. They are more common in homes, while client/server networks are more likely to be used by businesses.

Types of Network Connections

There are also different types of network connections that concern how elements in a network are connected to each other. Topologies are used to connect computers, with a collapsed ring being the most common type due to the Ethernet supporting the internet, local area networks and wide area networks.

Here are some of the topologies that are used to create networks:

Star Topology

A central node connects a cable to each computer in the network in a star topology. Each computer in the network has an independent connection to the center of the network, and one connection breaking won’t affect the rest of the network. However, one downside is that many cables are required to form this kind of network.

Bus Topology

In a bus topology network connection, one cable connects the computer. The information for the last node on the network has to run through each connected computer. There is less cabling required, but if the cable breaks it means that none of the computers can reach the network.

Ring Topology

A ring topology is similar to a bus topology. It uses a single cable with the end nodes connected to each other so the signal can circle through the network to find its recipient. The signal will try several times to find its destination even when the network node is not working properly. A collapsed ring has a central node which is a hub, router or switch. The device has an internal ring topology and has places for cable to plug in. Every computer in the network has its own cable to plug into the device. In an office, this probably means having a cabling closet, where all computers are connected to the closet and the switch.

Network Protocols

Network protocols are the languages that computer devices use to communicate. The protocols that computer networks support offer another way to define and group them. Networks can have more than one protocol and each can support different applications. Protocols that are often used include TCP/IP, which is most common on the internet and in home networks.

Wired and Wireless Networks

Many protocols can work with both wired and wireless networks. In recent years, however, wireless technologies have grown and become much more popular. Wi-Fi and other wireless technologies have become the favorite option for building computer networks. One of the reasons for this is that wireless networks can easily support different types of wireless gadgets that have become popular over the years, such as smartphones and tablets. Mobile networking is now an important thing to consider because it’s not going to go away anytime soon.

Key Networking Terms

Open system: an open system is connected to the network and prepared for communication.

Closed system: a closed system is not connected to the network and so can’t be communicated with.

‍IP (internet protocol) address: the network address of the system across the network, which is also known as the Logical Address).

MAC address: the MAC address or physical address uniquely identifies each host. It is associated with the Network Interface Card (NIC).

Port: a port is a channel through which data is sent and received.

Nodes: nodes is a term used to refer to any computing devices such as computers that send and receive network packets across the network.

Network packets: the data that is sent to and from the nodes in a network.

Routers: routers are pieces of hardware that manage router packets. They determine which node the information came from and where to send it to. A router has a routing protocol which defines how it communicates with other routers.

‍Network address translation (NAT): a technique that routers use to provide internet service to more devices using fewer public IPs. A router has a public IP address but devices connected to it are assigned private IPs that others outside of the network can’t see.

Dynamic host configuration protocol (DHCP): assigns dynamic IP addresses to hosts and is maintained by the internet service provider.

Internet service providers (ISP): companies that provide everyone with their internet connection, both to individuals and to businesses and other organizations.

Computer network

A computer network is an interconnection of a group of computers. Networks may be classified by what is called the network layer at which they operate according to basic reference models considered as standards in the industry such as the four-layer Internet Protocol Suite model. While the seven-layer Open Systems Interconnection (OSI) reference model is better known in academia, the majority of networks use the Internet Protocol Suite (IP) as their network model.

Contents

By scale [ ]

Computer networks may be classified according to the scale: Personal area network (PAN), Local Area Network (LAN), Campus Area Network (CAN), Metropolitan area network (MAN), or Wide area network (WAN). As Ethernet increasingly is the standard interface to networks, these distinctions are more important to the network administrator than the end user. Network administrators may have to tune the network, based on delay that derives from distance, to achieve the desired Quality of Service (QoS). The primary difference in the networks is the size.

Controller Area Networks are a special niche, as in control of a vehicle’s engine, a boat’s electronics, or a set of factory robots.

By connection method [ ]

Ethernets use physical wiring to connect devices. Often, they employ the use of hubs, switches, bridges, and routers.

Wireless LAN technology is built to connect devices without wiring. These devices use a radio frequency to connect.

By functional relationship (Network Architectures) [ ]

By network topology [ ]

Network Topology signifies the way in which intelligent devices in the network see their logical relations to one another. The use of the term «logical» here is significant. That is, network topology is independent of the «physical» layout of the network. Even if networked computers are physically placed in a linear arrangement, if they are connected via a hub, the network has a Star topology, rather than a Bus Topology. In this regard the visual and operational characteristics of a network are distinct; the logical network topology is not necessarily the same as the physical layout.

By protocol [ ]

Computer networks may be classified according to the communications protocol that is being used on the network. See the articles on List of network protocol stacks and List of network protocols for more information. For a development of the foundations of protocol design see Srikant 2004 [1] and Meyn 2007 [2]

Types of networks: [ ]

Below is a list of the most common types of computer networks in order of scale.

Personal Area Network (PAN) [ ]

Template:Main A personal area network (PAN) is a computer network used for communication among computer devices close to one person. Some examples of devices that may be used in a PAN are printers, fax machines, telephones, PDAs or scanners. The reach of a PAN is typically within about 20-30 feet (approximately 4-6 Meters). PANs can be used for communication among the individual devices (intrapersonal communication), or for connecting to a higher level network and the Internet (an uplink).

Local Area Network (LAN) [ ]

The staff computers (bright green) can get to the color printer, checkout records, and the academic network and the Internet. All user computers can get to the Internet and the card catalog. Each workgroup can get to its local printer. Note that the printers are not accessible from outside their workgroup.

Typical library network, in a branching tree topology and controlled access to resources

All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbps Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called «layer 3 switches» because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks’ customer access routers.

Depending on the circumstance, the computers in the network might be connected using cables and hubs. Other networks might be connected strictly wirelessly. It depends on the number of PCs that you are trying to connect, the physical layout of your workspace, and the various needs of network. Not shown in this diagram, for example, is a wireless workstation used when shelving books.

The defining characteristics of LANs, in contrast to WANs (wide area networks), include their much higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 100 Gbit/s, and possibly 40 Gbit/s. Inverse multiplexing is commonly used to build a faster aggregate from slower physical streams, such as bringing 4 Gbit/s aggregate stream into a computer or network element with four 1 Gbit/s interfaces.

Campus Area Network (CAN) [ ]

Template:Main A network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, or a military base. A CAN, may be considered a type of MAN (metropolitan area network), but is generally limited to an area that is smaller than a typical MAN.

Metropolitan Area Network (MAN) [ ]

Template:Main A Metropolitan Area Network is a network that connects two or more Local Area Networks or Campus Area Networks together but does not extend beyond the boundaries of the immediate town, city, or metropolitan area. Multiple routers, switches & hubs are connected to create a MAN.

Wide Area Network (WAN) [ ]

Global Area Network (GAN) [ ]

Internetwork [ ]

Template:Main Two or more networks or network segments connected using devices that operate at layer 3 (the ‘network’ layer) of the OSI Basic Reference Model, such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.

In modern practice, the interconnected networks use the Internet Protocol. There are at least three variants of internetwork, depending on who administers and who participates in them:

Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet itself is not considered to be a part of the intranet or extranet, although the Internet may serve as a portal for access to portions of an extranet.

Intranet [ ]

Template:Main An intranet is a set of interconnected networks, using the Internet Protocol and uses IP-based tools such as web browsers, that is under the control of a single administrative entity. That administrative entity closes the intranet to the rest of the world, and allows only specific users. Most commonly, an intranet is the internal network of a company or other enterprise.

Extranet [ ]

Template:Main An extranet is a network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g. a company’s customers may be given access to some part of its intranet creating in this way an extranet, while at the same time the customers may not be considered ‘trusted’ from a security standpoint). Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.

Internet [ ]

Basic Hardware Components [ ]

Network Interface Cards [ ]

Repeaters [ ]

Template:Main A repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.

Because repeaters work with the actual physical signal, and do not attempt to interpret the data being transmitted, they operate on the Physical layer, the first layer of the OSI model.

Template:Main A hub contains multiple ports. When a packet arrives at one port, it is copied to all the ports of the hub. When the packets are copied, the destination address in the frame does not change to a broadcast address. It does this in a rudimentary way, it simply copies the data to all of the Nodes connected to the hub. [4]

Bridges [ ]

Template:Main A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do not promiscuously copy traffic to all ports, as hubs do. but learns which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.

Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.

Bridges come in three basic types:

Switches [ ]

Overemphasizing the ill-defined term «switch» often leads to confusion when first trying to understand networking. Many experienced network designers and operators recommend starting with the logic of devices dealing with only one protocol level, not all of which are covered by OSI. Multilayer device selection is an advanced topic that may lead to selecting particular implementations, but multilayer switching is simply not a real-world design concept.

Routers [ ]

Template:Main Routers are the networking device that forward data packets along networks by using headers and forwarding tables to determine the best path to forward the packets. Routers work at the network layer of the TCP/IP model or layer 3 of the OSI model. Routers also provide interconnectivity between like and unlike media (RFC 1812) This is accomplished by examining the Header of a data packet, and making a decision on the next hop to which it should be sent (RFC 1812) They use preconfigured static routes, status of their hardware interfaces, and routing protocols to select the best route between any two subnets. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP’s network. Some DSL and cable modems, for home use, have been integrated with routers to allow multiple home computers to access the Internet.

Building a simple computer network [ ]

Practical networks generally consist of more than two interconnected computers and generally require special devices in addition to the Network Interface Controller that each computer needs to beuipped with. Examples of some of these special devices are hubs, switches and routers.

Ancillary equipment used by networks [ ]

To keep a network operating, to diagnose failures or degradation, and to circumvent problems, networks may have a wide-ranging amount of ancillary equipment.

Providing Electrical Power [ ]

A network as simple as two computers linked with a crossover cable has several points at which the network could fail: either network interface, and the cable. Large networks, without careful design, can have many points at which a single failure could disable the network.

When networks are critical the general rule is that they should have no single point of failure. The broad factors that can bring down networks, according to the Software Engineering Institute [6] at Carnegie-Mellon University:

Dealing with Power Failures [ ]

One obvious form of failure is the loss of electrical power. Depending on the criticality and budget of the network, protection from power failures can range from simple filters against excessive voltage spikes, to consumer-grade Uninterruptible Power Supplies (UPS) that can protect against loss of commercial power for a few minutes, to independent generators with large battery banks. Critical installations may switch from commercial to internal power in the event of a brownout,where the voltage level is below the normal minimum level specified for the system. Systems supplied with three-phase electric power also suffer brownouts if one or more phases are absent, at reduced voltage, or incorrectly phased. Such malfunctions are particularly damaging to electric motors. Some brownouts, called voltage reductions, are made intentionally to prevent a full power outage.

To help standardize approaches to power failures, the Advanced Configuration and Power Interface (ACPI) specification is an open industry standard first released in December 1996 developed by HP, Intel, Microsoft, Phoenix and Toshiba that defines common interfaces for hardware recognition, motherboard and device configuration and power management.

Monitoring and Diagnostic Equipment [ ]

Networks, depending on their criticality and the skill set available among the operators, may have a variety of temporarily or permanently connected performance measurement and diagnostic equipment. Routers and bridges intended more for the enterprise or ISP market than home use, for example, usually record the amount of traffic and errors experienced on their interfaces.

Diagnostic equipment, to isolate failures, may be nothing more complicated than a spare piece of equipment. If the problem disappears when the spare is manually replaced, the problem has been diagnosed. More sophisticated and expensive installations will have spare elements that can automatically replace a failed unit. Failures can be made transparent to user computers with techniques such as the Virtual Router Redundancy Protocol (VRRP), as specified in RFC 3768.

See also [ ]

References [ ]

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