Networks A network of computers (also known as network computers or computer network) is a set of equipment (hardware and / or devices) connected by cables, signals, waves or any other method of data transport, which share information (files) resources (CD-ROM, printers, etc..) and services (Internet access, e-mail, chat, games, etc.). in other words A network is a data transmission system that enables the exchange of information between computers. A network is a set of interconnected devices to each other. The networks generally consist of "shared resources"

OBJECTIVES OF A NETWORK Is to make all programs, data and equipment are available to anyone on the network that requests it, regardless of physical location of the resource and user. A second objective is to provide a high reliability, to have alternative sources of supply. Another objective is the economic savings. Small computers have a better cost / performance compared to that offered by large machines. Another objective of establishing a network of computers is that you can provide a powerful means of communication between people who are very far apart from each other.

CLASSIFICATION OF COMPUTER NETWORKS BY LAYER NETWORK Computer networks can be classified according to the network layer in which they operate according to some basic reference models that are considered to be standard in the industry such as the OSI model of seven layers model and TCP / IP five layers.

THE SCALE Computer networks can be classified according to the scale or extent of reach of the network, such as personal area network (PAN), local area network (LAN), campus area network (CAN), network metropolitan area (MAN) or wide area network (WAN).

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

BY THE CONNECTION METHOD Computer networks can be classified according to the technology used to connect individual devices on the network such as HomePNA, online communications, Ethernet or wireless LAN power.

THE FUNCTIONAL RELATIONSHIP Computer networks can be classified according to functional relationships between network elements, such as active server of the establishment of a network, and client architectures of Peer-to-peer (workgroup). Also, computer networks are used to send data from one to another by the hardrive.

BY NETWORK TOPOLOGY Defined as being connected computers, printers, network devices and other devices. In other words, a network topology describes the arrangement of cables and devices, as well as the routes used for data transmissions. Greatly influenced by the topology of network operations. The topologies are: bus, ring or double ring, star, extended star, hierarchical and mesh.

SERVICES PROVIDED BY Computer networks can be classified according to the services they provide, such as store networks, server farms, networks, process control, value added network, wireless network of the community, etc.

FOR PROTOCOL Computer networks can be classified according to the communication protocol being used on the network. See the articles on the list of network protocol stacks and the list of network protocols for more information.

TYPE OF NETWORK FOR DIRECTIONAL DATA (TYPE OF TRANSMISSION) DIRECTIONAL SIMPLEX UNIDIRETIONAL HALF-DUPLEX FULL-DUPLEX

DEFINICION-CAPACIDADES A transmitter sends a receiver But not simultaneous bidirectional network (a single transmitter at a time) Network that allows bi-directional transmission and reception while

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

BY NETWORKS PROTOCOL Network standars IEEE 802.3, standard Ethernet IEEE 802.5, standardToken Ring IEEE 802.11, standard Wi-Fi IEEE 802.15, standard Bluetooth For scientific and engineering discipline studying computer networks. A computer network is the set of computers connected together with a telecommunications system to communicate and share resources and information.

TYPES OF NETWORKS INTERNAL NETWORK Two or more networks or network segments connected to devices that operate at layer 3 (layer of the "network") of the basic reference model of OSI, such as a router. Note: Any interconnection between networks of public, private, commercial, industrial, or government can also be defined as internal network. These networks can communicate to the outside using NAT.

INTERNET A specific network, is a global network of governmental, academic, public and private based on the Advanced Research Projects Agency Network (ARPANET) developed by Warren of the U.S. Department of the defense also home to the World Wide Web (WWW) and designated the "Internet" with a capital "I" to distinguish it from other generic Internetworks.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

EXTRANET An internal network that is limited in scope to a single organization or entity but which also has limited connections to networks of one or more generally, but not necessarily, trusted organizations or entities. Note: An extranet can also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet will not be a single LAN, because an extranet must have at least one connection to a network outside. Intranets and extranets may or may not have Internet connections. If you are connected to the Internet, Intranet or extranet is normally protected against being hit the Internet without proper authorization. The Internet itself is not considered to be part of an intranet or extranet, although the Internet can serve as a portal for access to portions of an extranet.

INTRANET An intranet is a private network that uses Internet technology as a basic architecture. An internal network is built using the TCP / IP for Internet communication, which can run on many hardware platforms and cable projects. The hardware key is not in itself an intranet; protocols are essential for the software. Intranet technology can coexist with other local area network. In many companies, the "system property" to include existing central systems, Novell networks, mini - computers and databases, are integrated into an intranet. A wide variety of tools allowing to happen. The common interface (CGI) is often used to access databases from a proprietary intranet. The Java programming language can also be used to access proprietary databases. Security in an intranet is more complicated to implement, since it is providing security both internal and external users, who are supposed to have permission to use network services. An intranet or internal network is limited in scope to a single organization or entity. Usually provide services such as HTTP, FTP, SMTP, POP3 and other general use. In an intranet you can have the same services on the Internet, but they are only available to users of this private network, not to general users.

NETWORK CLASSIFICATION BY SCOPE: • Personal Area Network (PAN) (Personal Area Network) is a computer network used for communication among computer devices (phones, including personal digital assistants) close to a person. The devices may or may not belong to the person in question. The scope of a PAN is typically a few meters. The PAN can be used for communication between personal devices themselves (intrapersonal communication) or to connect to a high-level network and the Internet (up a link). Personal area networks may be connected with cables to the

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

computer buses such as USB and FireWire. A network of wireless personal area (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth. • Local Area Network (LAN): a network that is limited to a special area as a relatively small room, one building, a ship or an airplane. Local area networks are sometimes called a single network location. Note: For administrative purposes, large LANs are often divided into smaller logical segments called Workgroups. A Workgroups is a group of computers that share a common system of resources within a LAN. • CAMPUS AREA NETWORK (CAN): It results in a network that connects two or more LANs that must be connected to a specific geographic area such as a university campus, an industrial complex or a military base. • Metropolitan Area network (MAN): A network that connects a network of two or more local area together, but does not extend beyond the immediate boundaries of the city or the metropolitan area. Routers (routers) multiple switches (switch) and the cubes are connected to create a MAN.

• Wide Area Network (WAN) is a data communications network covering a relatively wide geographic area and often uses transmission facilities provided by common carriers such as telephone companies. WAN technologies generally operate at the three lower layers of the OSI reference model: physical layer, the layer of data transmission, and network layer.

• PUBLIC RED: a public network is defined as a network that anyone can use and not the networks that are configured with a personal password. It is a network of interconnected computers capable of sharing information and allowing users to communicate regardless of geographical location.

• PRIVATE NETWORK: A private network is defined as a network that only certain people can use and that are configured with a personal password.

METHOD FOR THE CONNECTION: • GUIDED MEDIA: coaxial cable, twisted pair cable, fiber optic and other cables.

 COAXIAL CABLE: He was a great value for its transmission of voice, audio, video, text and images. Is structured by the following components from the

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

inside out: • A core of solid copper or copper coated steel. • An insulating layer that reduces the kernel or driver, usually poly vinyl material. • A layer of metal lineage usually copper or aluminum from tissue whose function is to keep tight to eliminate the interference. • Finally has a layer of coating that normally chloride, and polyethylene xelón uniform to maintain signal quality.

 Twisted pair cable: It's the oldest in the market and some types of applications is the most common. It consists of two copper wires or sometimes aluminum, insulated and a thickness of about 1 millimeter. The wires are twisted to reduce electrical interference from nearby peers. An example is the twisted pair telephone system, now have become a standard in the field of local networks, the standard color for this purpose are: Orange / White - Orange Green / White-Green White / Blue-Blue White / Brown - Brown

 FIBER OPTIC CABLE: They are much lighter and smaller diameter. Furthermore, the density of information that are capable of transmitting is greater. The emitter is formed by a laser that emits a powerful beam of light which varies according to the electrical signal reaches the receiver consists of a photodiode that converts incident light into electrical signals again.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

Among its features are: • They are compact. • Light • Low signal loss • Large transmission capacity • High degree of reliability because they are immune to electromagnetic interference. • Finally has a layer of coating that normally chloride, and polyethylene xelón uniform to maintain signal quality.  NO MEDIA GUIDED: radio, infrared, microwave, laser and other wireless networks.

BY FUNCTIONAL RELATIONSHIP •

CLIENT-SERVER: Instead of building systems as a monolithic, there

is general agreement as to build client / server system. The client (a PC user) requests a service (such as print) that gives you a server (a processor connected to the LAN). Common approach to the structure of computer systems leads to a separation of the functions previously forms a whole. The details of the performance range from simple approaches to the real possibility to manage all the computers in •

MATCH-A-LIKE (P2P)

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

a

uniform

way.

NETWORK ARCHITECTURE BY NETWORK TOPOLOGY: BUS: This topology allows all stations receive the information transmitted; a transmitting station and all the others listen. It consists of a cable with a terminator at each end of that crash all the elements of a network. All network nodes are connected to the cable which is called the "Backbone Cable. ADVANTAGES: • Allows you easily increase or decrease the number of stations. • Failure of any node does not prevent the network continues to function normally, which can add or remove nodes without disrupting its operation. DISADVANTAGES • Any break in the bus prevents the normal operation of the network and the fault is very difficult to detect. • The control of information flow inconveniences due to several stations try to transmit at a time and there is a single bus, which only achieved a transmission.

TREE:

This structure is used in cable television applications, which could be based on the future structures of networks that reach households. It has also been used in applications of local analog.

MESH:

This involves or is made via a WAN, a mesh network provides multiple paths, if one path fails or is congested traffic, a packet may use a different path to the destination. Routers are used to interconnect separate networks.

RING:

The stations are linked with each other forming a circle using a common cable. The last node in the chain connects to the first closing of the ring. Signals traveling in one direction around the circle, regenerating at each node. Using this methodology, each node examines the information that is sent through the ring. If the information is not directed to the node that review, go to the next in the ring. The disadvantage is that if the ring breaks a connection, it drops the network.

ADVANTAGES: • This topology can increase or decrease the number of stations with ease. • The speed depends on the flow of data, as more stations attempt to use the network will be slower the flow of information.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

DISADVANTAGES: A failure in any part leaves blocked the whole network.

RED STAR: The star topology is characterized by all nodes connected to a central controller. All transactions pass through the central node, which is responsible for managing and monitoring all communications. For this reason, the failure of a particular node is easy to detect and does not harm the rest of the network, but a failure in the hub off the network. One way to avoid a single central controller and also increase the connection limit of nodes, as well as better adaptation to the environment, would be to use a star topology distributed. The disadvantage of this type of topology is that it increases the number of maintenance.

ADVANTAGES: • It has good flexibility to increase the number of computers connected to the network. • If the computer fails to the behavior of the network continues without problems, however, if the problem occurs in the central control affects the entire network. • Diagnosis of problems is simple, because all computers are connected to a central controller.

DISADVANTAGES: • It is not suitable for large installations due to the amount of cable to be grouped in the central controller. • This setting is for fast communications between stations or nodes and the controller, but the communication between stations is slow. Mixed (any combination of the above).

MIXED: (any combination of the above).

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

CRITERION WHEN CHOOSING A NETWORK TOPOLOGY: • Seek to minimize the cost of routing (need to choose the simplest path between the node and the others). • Tolerance or failure to ease location of these. • Ease of installation and reconfiguration of network.

CLASSIFICATION OF THE NETWORK ACCORDING TO DISTRIBUTION LOGIC: All computers have a client and server side: A server machine may be a service, but customer service. • SERVER: Machine that provides information or services to the rest of the posts in the network. The type of information or services offered determines the type of server it is: print server, file, web pages, and mail.etc. • CUSTOMER: Machine to access information from servers or use its services. Examples: Whenever we see a web page we are behaving like customers. Customers if we also use the print service on a remote computer network.

BASIC COMPONENTS OF COMPUTER NETWORKS THE COMPUTER Most of the components of a computer network half are single, also called host, usually work sites (including personal computers) or servers.

BUILDING A NETWORK OF COMPUTERS

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

A SIMPLE NETWORK A simple computer network can be constructed from two computers by adding a network adapter (network interface controller (NIC) to each computer and connected via a special cable called a "crossover cable" (which is a cable network with some cables reversed, to avoid using a router or switch). This type of network is useful for transferring information between two computers that are not normally connected by a network connection or for a permanent home base for the establishment of a network. Alternatively, a network between two computers can be established without dedicated extra apparatus, using a standard connection such as RS-232 serial port on both computers, connected via a special crossover cable null modem. This type of network only you must configure an IP address, since there is not a server that automatically assigns IP.

PRACTICE NETWORK Networking practices usually consist of more than two interconnected computers and generally require special devices in addition to the network interface controller to each computer must be equipped. Examples of some of these special devices are hubs (hubs), multiplexers (switches) and routers (routers).

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

CHARACTERISTICS OF A NETWORK. • A network covering a limited area. • is confined to a limited area. • Share a more common means of transmission. • High-speed transfer. This is increased each day, using increasingly sophisticated technologies. • Flexibility. • An increasingly important concept, and should be understood by the network capacity to accommodate the needs of users • Reliability. • Term discussed it raises the level of data security, as expressed by the facilities and resources available networks. • Security. • The network infrastructure components and their environments within ei facilities. • Operations. • Supported on top of easy installation and handling of components of the computer network

TYPES OF WORK SITES There are many types of work sites that can be incorporated into a particular network, something which has exhibits of high-end systems with multiple CPUs, large amounts of RAM, large amounts of storage space on hard disk, or other components required for the work of special data processing, graphics, or other intensive uses of the resource. (See also computer network).

USE OF COMPUTER NETWORKS IN TEAMWORK Entities in the accelerated development of science and technology policy, organization and business improvement projects, create the conditions necessary for the implementation of the Integrated Management of Projects (DIP) with the support of the New Technologies of Information and Communication (NTIC) to obtain the goals, shortening the timeframe, within budget and with the quality required in investment projects.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

• DUMB TERMINAL: many networks use this type of equipment instead of jobs for data entry. These data will only be displayed or entered. Such terminals, working against a server, who actually processes the data and sends display data to the terminals. • OTHER DEVICES: there are many other types of devices that can be used to build a network, many of which require an understanding of advanced concepts of establishing a network of computers before they can be easily understood (eg, cubes , routers, bridges, switches, hardware firewalls, etc.).. In the mobile and home networks, which connect consumer electronics devices such as video game consoles are becoming increasingly common.

COMPONENTS OF A NETWORK • SERVER: The server is the machine's main network, which manages network resources and the flow of information. • STATION OF WORK: This is a computer that is physically connected to the server via some sort of cable. • Network Operating System: The system (Software) which is responsible for managing and controlling the network in general. • Communication protocols: These are a set of rules governing the transmission and reception of data over the network. • The Network Interface Card: Provides connectivity from the user terminal or the physical network, which handles the protocols and protocol specified topology.

NETWORK SERVICES. • ACCESS: The access services are responsible both for verifying the identity of the user • File: The file service is to offer the large storage capacity network to download or delete the records of the stations.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

PRINT: Allows you to share printers between multiple computers on the network, thus avoiding the need for a printer for each computer. • INFORMATION: The server can store information database for consultation by users or other information.

TYPES OF SERVERS • FILE SERVER: stores various types of files and distributes them to other clients on the network. • PRINT SERVER: control of one or more printers and accepts print jobs from other clients on the network, putting in the work queue print (although you can also change the priority of the different views), and performing most or all other functions in a work site would be done to achieve a print job if the printer is connected directly to the printer port from the work site. • MAIL SERVER: A store, sends, receives, routes, and performs other operations related to email clients on the network.

• FAX SERVER: stores, sends, receives, routes, and performs other functions necessary for the transmission, receipt and distribution of the fax.

• TELEPHONY SERVER: performs functions related to telephony, such as the answering machine, performing the functions of a system for interactive voice response, storing the voice messages, route calls and controlling the network or Internet, p. eg. The excessive entry of voice IP (VoIP), etc.. • PROXY SERVER: A certain type of functions on behalf of other clients on the network to increase the performance of certain operations (eg., Prefetching and deposit documents or other data requested very frequently), also serves as safety, this it has a Firewall. Allows Internet access in a computer network allowing or denying access to different Web sites. • REMOTE ACCESS SERVER (RAS) controls the modem lines of monitors, or other channels of communication network to connect calls to the network from a remote position, answered phone calls or acknowledge the incoming call and the network perform the necessary security checks and other necessary procedures to register a user on the network.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

• SERVER USAGE: Conducts the logic of science or business use of a customer accepting the instructions for the operations of a job and serving the results to turn the job site, while the work-site operator interface makes the GUI portion of the process (ie, the logic of the presentation) is required to work properly. • WEB SERVER: stored HTML documents, images, text files, scripts, and other web material composed of data (collectively known as content), and distributes this content to clients who request it on the network. • BACK SERVER: has the backup software installed on the network and has large amounts of network storage on hard drives or other storage (tape, etc..) Available for use to ensure that the loss of a primary server does not affect the network. This technique is called clustering. • OTHER DEVICES: there are many other types of devices that can be used to build a network, many of which require an understanding of advanced concepts of establishing a network of computers before they can be easily understood (eg, cubes , routers, bridges, switches, hardware firewalls, etc.).. In the mobile and home networks, which connect consumer electronics devices such as video game consoles are becoming increasingly common.

GLOSSARY • NETWORKING: A set of equipment (hardware and / or devices) connected by cables, signals, waves or any other method of data transport, which share information (files), resource (CD-ROM, printers, etc.. ) and services (Internet access, e-mail, chat, games)

• PACKET SWITCHING: The method consists in dividing all the information that comes from a computer to be transmitted over the network in fixed block length (packets) that contain information regarding the origin and destination of the package and the order holding conducted within the division. This allows each bundle to move independently of the network and arrive at your destination can be reassembled to build the information sent back. • HARDWARE: Physical components of a computer or a network, unlike the programs or software elements that make them work. • HUB (hub): Simulates a hub in the network that connects to the connected computers.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

• INTERNET: All networks and routers that use the TCP / IP to form a single virtual network cooperative. • MODEMS: Equipment used to adjust the digital signals from one computer to a telephone line or an integrated services digital network, through processes called modulation (for reporting) and demodulation (for information). • NODES: "Point of intersection or union of several elements that come together in the same place." Example: on a computer network, each machine is a node, and if the network is the Internet, each server is also a node. • PROTOCOL: formal description of message formats and rules that two or more computers must follow to exchange messages. Protocols can describe low-level details of the interfaces or from computer to computer exchanges between application programs. • PROXY: This refers to a program or device that performs an action of another, its purpose is the most common proxy used to allow Internet access to all computers in an organization where you can only have a single computer connected, this is a unique IP address.

• OPERATING SYSTEM: Set of programs or software designed to allow communication with a user's computer and manage its resources efficiently.

• SOFTWARE: All programs, documents, processes, and routines associated with the operation of a computer system, ie the intangible part of a computer or logic.

• SWITCH (switch or switch) device interconnected computer networks. A switch connects two or more network segments, moving data from one network to another, according to the destination address of the datagrams in the network. The switches are used when you want to connect multiple networks, given that they act as a filter in the network, improves performance and safety. • TCP / IP protocol that provides reliable transmission of packet data networks. The name TCP / IP protocols from two major families, the Transmission Control Protocol (TCP) and Internet Protocol (IP). Together they become over 100 different protocols.

Técnico en sistemas: Leidy Yohana Jaramillo Lenis

BIBLIOGRAPHY:  www.google.com  www.Monografias.com  www.tecnoconstruccion.blogspot.com  www.wapedia.com  www.wikipedia.com

Follow the links and learn more...

Técnico en sistemas: Leidy Yohana Jaramillo Lenis