Computer networks can usually be attributed to one of three groups, depending on their size and functions. Local area network (LAN, Local Area Network, LAN) is the main class of computer networks. LAN architecture can vary between simple (two computers connected by a cable) and complex (hundreds of computers and peripheral devices, networked in a larger organization). The distinctive feature of BOS is that it exists within a limited geographical area, such as a building or a Department of the company (as a rule, does not exceed 5 km in diameter). If the computers in the network, are located in several buildings on a large urban area, the network is sometimes referred to as regional or city network (Metropolitan Area Network, MAN, usually located in diameter 5-50 km). In contrast to these classes, the global network of networks (Wide Area Network, WAN) has no geographic boundaries and can connect between computers and peripheral devices that are on different sides of the world. In most cases, the global network consists of several interconnected LANs. Perhaps the Internet can be regarded as the ultimate global network.
Advantages of computer networks
If the computers run independently, applications and resources (such as printers or scanners) need to duplicate for each of them. For example, if two analyst willing to work with an Excel spreadsheet and print out the results of its work to a printer, both of the computers must have its own copy of the Excel program and your printer. If users need to jointly apply their data, those data would have to be continuously transferred between computers using a floppy disk or a CD-RW drive. If users need to use their computers together, each of them would have to make an effort to understand the other system, because each of them has its own desktop and application organization, its folder structure and so on. If the network added more users, then all they could jointly use Excel, data, and resources in the same way. In other words, computers that are members of the network can share:
- documents (memos, spreadsheets, invoices, etc.);
- electronic mail messages;
- software text;
- software for project support;
- illustrations, photographs, video and audio files;
- live audio or video stream;
- CD-ROM drives and other removable storage devices (such as Zip drives and Jaz drives);
- hard drives.
Because a computer network is a set of computers, better manage the entire network from a central point (network administrator, network administrator). Take the above example and assume that our analysts gave the new version of Excel. If their computers are not networked, each system will have to upgrade and test separately. It’s not so difficult to do, if only the two systems. But if your company has tens or even hundreds of personal computers, to hold individual modernization of each, of course, is expensive and ineffective exercise. If you have a computer network, to upgrade the application, the upgrade is performed once on the server and all workstations of this computer network will be able to immediately begin using the updated software. Centralized administration allows you to manage the security of computer network and monitor its work.
But in addition to sharing information, computer networks provide other advantages. NET allows you to store and protect information. For example, it is very difficult to coordinate and manage the process of reservation information with a large number of independent PCs. The system organized into a computer network, can automatically create backup files in one central site (for example, tape device connected to a network server). If the information on a particular computer is lost, it can be easily found in the central nervous system backup and restore. In addition, the level of data security. Access to a personal computer, usually means access to all of the information contained in this computer. However, security capabilities, which provides computer network will not allow unauthorized users to gain access to important information or delete it. For example, every network user has your registration (“loginnoe”), the user name and password that give access only to a limited number of network resources. Finally, computer networks are ideal environments for communication between users. Instead of exchanging paper reminders and notes, electronic mail allows users to send each other letters, reports, images, almost all file types. It also allows you to save money on print materials and reduce delays with the delivery of the correspondence between divisions of the company. Email is a powerful tool that enables Internet users to exchange messages almost instantaneously, almost regardless of its location in the world.
Author: Jaringan Komputer
Today, enterprises and institutions have been widely used LAN, the main purpose of which provide access to network-wide (information, software and hardware) resources. In addition, LAN enterprises allow employees to quickly share information with each other.
LANs are used to solve such problems as:
- Data distribution. Data stored in a local network to a central computer and can be accessed by the workstations. In this regard, it is not necessary to have each workplace drives for storing the same information;
- Allocation of resources. Peripheral devices can be accessible to all users on the LAN. Such devices may be, for example, a scanner or a laser printer;
- Distribution programs. All users can share the LAN have access to programs that have been centrally installed on one computer.
Basics of Local Area Networks
Local area network (LAN) is a compound with multiple PCs using appropriate hardware and software. In local networks the data rate is high in comparison with the protocols of the WAN protocols are relatively simple, there is no redundancy of communication channels.
LANs depending on the administrative relationships between computers are divided into:
- hierarchical or centralized;
Local network according to the physical and logical relationships between different computer architectures (Ethernet, Token Ring, FDDI, etc.) and topology (bus, ring, star, etc.).
In local area networks implemented technology “client – server”. Server – an object (computer or program) that provides maintenance services, and the client – an object (or computer program) that requests the server to provide these services.
In ad-hoc networks may be simultaneously server and the client, i.e. use the resources of another computer or the same PC, which he provides resources.
Server in hierarchical networks can be a client server only a higher level of the hierarchy. Hierarchical networks are called network with a dedicated server. Computers on the local area network, called nodes. Each node can be a server or workstation.
Peer to Peer (single level) LAN
- An ad hoc network – a network of peer computers (workstations), each of which has a unique name and password to log into the computer. An ad-hoc network does not have a central PC.
- An ad-hoc or one-tier LAN
In ad hoc network, each workstation can share all of its resources with other workstations network. The workstation can share some resources, but may not provide any resources to other stations. For example, some hardware (scanners, printers, hard drives, drives CD-ROM, and others.) Connected to a separate PC used together in all workplaces.
Each user is the administrator of an ad hoc network on your PC. Peer networks are used for networking a small number of computers – no more than 10-15. Peer network may be arranged, for example, using the Windows 95, 98, 2000, Windows XP or other operating systems.
For access to the resources of workstations in an ad hoc network log folder in My Network Places, double-click the My Network Places icon and select View workgroup computers. After this, the screen will display computers that are part of an ad hoc network by clicking on the icons of computers, you can open the logical drives and folders with a network-wide resources.
Hierarchical (multilevel) LANs
Hierarchical LAN – local area networks in which there are one or more special computers – servers on which information is stored, shared by different users. Hierarchical LANs – is usually a LAN with a dedicated server, but there are unallocated network and server. In networks with a listen server function workstations and servers combined. Workstations, included in a hierarchical network can simultaneously organize among themselves peer LAN.
Hierarchical or multilevel LANs
Dedicated servers are usually a high-performance computers with high-capacity hard drives. Installed on the server network operating system, connected to it all external devices (printers, scanners, hard drives, modems, etc.). Provisioning server in a hierarchical network is at the user level.
Each user must be registered with the network administrator with a unique name (login) and users must assign a password under which will be included in the PC and the network. In addition, when users log network administrator allocates to them the necessary resources on the server and access rights to them.
The computer from which the access to information on the server, called workstations, or customers. They installed a standalone operating system and the client part of the network operating system. In the local operating systems Windows 95, 98, 2000, Windows XP is on the client side such as network operating systems: Windows NT Server, Windows 2003 Server.
Depending on the usage of the server in the hierarchical LAN distinguish the following types of servers.
File server. In this case, the server are processed jointly shared files and programs.
Database server. Located on the server network database. The database server can be replenished from different workstations and provide information on requests from workstations.
Access Server – a dedicated computer on your local network for remote processing tasks. The server performs the job received from a remote workstation, and sends the results to a remote workstation. In other words, a server for remote access (e.g., mobile computer) to LAN resources.
Server – printing. For low-power computer connected enough performance printer that can print information from several workstations. The software organizes the print queue.
Mail server. The server stores information, send and receive both the LAN and external modem. The user can view his name entered the information or send via e-mail server your information.
Peer and hierarchical LAN has its own advantages and disadvantages. Selecting type LAN depends on the requirements imposed on its cost, reliability, processing speed, privacy information, etc.
Author: Jaringan Komputer
Ways To Build Local Networks
Computer network – a complex set of interrelated and coordinated functioning of software and hardware components.
Computer network model can provide a multilayer consisting of layers:
- communications equipment;
- operating systems;
- network applications.
The foundation of any network are PCs that are connected to the network using a network card. All computers local networks can be divided into two classes: servers and workstations.
Network adapter – a special device that is designed for interfacing with a local computer network and to arrange a bi-directional communication network. The network card is inserted into a free slot on the motherboard and is equipped with its own processor and memory, and to connect to the network has a connector RJ-45. The most common type of card PCI, which are inserted into the PCI expansion slot on the motherboard. Depending on the technology used Ethernet, Fast Ethernet or Gigabit Ethernet network card and data transmission rate in the network may be 10, 100 or 1000 megabits / sec.
As a separate cable connects PCs and communications equipment used in local area networks:
- Twisted Pair – transmission line connection which consists of two wires twisted together with a certain pitch in order to reduce the effects of electromagnetic fields.
- Coaxial cable – cable, which consists of a central conductor and the second conductor insulator located on top of the insulator.
- Optical cable – a cable in which the information carrier is the light beam propagating through the optical fiber.
Furthermore, as a transmission medium in a wireless local area network using radio waves in the microwave range.
For communications equipment LANs include transceivers, repeaters, hubs, bridges, switches, routers, and gateways.
Part of the equipment (transceivers or transceivers, repeaters and hubs or repeaters or hubs) is used to connect several computers to the desired network configuration. PC connected to a hub to form a local network segment, i.e. Hubs are a means of structuring the physical network as well as breaking the network into segments that make it easy to connect to the network of a large number of PCs.
Another piece of equipment (bridges, switches) are used for logical structuring of the network. Since LANs are broadcast (Ethernet and Token Ring), then with an increase in the number of computers in a network built on the basis of hubs, increased latency access to computer networks and the emergence of conflicts. Therefore, in networks built on hubs or switches installed bridges between every three or four hubs, ie perform a logical structuring of the network in order to avoid collisions.
The third piece of equipment designed to combine multiple local area networks into a single network routers (routers), Gateways (gateways). This piece of equipment can be attributed, and bridges (bridges), and switches (switches).
- Repeaters – a device for recovery and amplification of signals in a network, serving to increase its length.
- Transceiver – a device for receiving packets from the network controller workstations and transfer them to the network. Transceivers (converters) can convert electrical signals into other signals (optical or radio) to use other transmission media.
- Hub – multiple-access device that combines one point separate physical cable lengths, form a common data transmission medium or network segments, ie Hubs are used to create segments and are a means of structuring the physical network.
- Bridges – a software – hardware devices that provide a combination of several LANs together. The bridges are intended for structuring the logical network connections or substantially identical networks having certain physical differences.
- Switche– software – hardware devices are fast analogue bridges that share a common environment data into logical segments. Logical segment formed by combining multiple physical segments via one or more hubs. Each logical segment is connected to a single port on the switch. When you receive data from the computer – send to any of the ports of the switch will transfer the data, but not on all ports in the Hub, but only to the port that is connected to a segment containing computer – the data receiver.
- Router – These devices provide data path selection between multiple networks having different architectures or protocols. They provide a sophisticated level of service as they can carry out “intelligent” functions: selection of the best route for the transmission of a message addressed to a different network; protection data; buffering data transferred; various protocol conversion. Routers are used only for communication homogeneous networks.
- Gateway) – device (computer), serving to consolidate disparate networks with different communication protocols. The gateways perform protocol conversion to the network, in particular the conversion of messages from one format to another.
The efficiency of the LAN is determined by the parameters defined for the network. Network configuration is based on existing technology and international expertise, as well as internationally accepted standards of building LAN and determined the requirements for it, as well as the financial capacity of organizations.
Based on the existing conditions and requirements in each case selected network topology, cabling, communications equipment, protocols and data transmission techniques, methods of interaction devices, network operating system
When the Computer network is needed
Look at today’s very busy state of the business, it seems that almost every merchant offers a network solution to increase sales, improve productivity and increase revenue. In many cases, companies simply are trying to persuade to invest in building a computer network without careful examination of costs and the proposed quality. If you are a Manager or responsible manager information services, then you may be wondering, how much will be justified by the material and technical costs related to the establishment of a computer network. Descriptions of the following problems will help you determine whether to build a computer network to bring your company’s benefit.
- Is your company or department spends the money for the purchase of additional hardware and software?. Computer networks make it possible to achieve an extremely high level of sharing information and resources, so the purchase of additional equipment in the form of printers, disk drives and software can be (eventually) even more expensive than building a network for sharing these resources. For example, the purchase or upgrade of ten new printers can cost more than installing a network printer. The advantage of this solution is not only the installation and maintenance of a network printer is easier and faster, but also in the fact that this printer will be able to use multiple network users.
- Due to inconsistencies of software errors and loss of productivity. This often happens when different users use different versions of the software. Files created in the old version of the application, can be read in its later versions, but not vice versa. For example, a document created in Word 6, can be easily opened in Word 2000, but not the other way around — and certainly not in Word for DOS. This limits the range of users who can use each document. This can also occur when different users use applications created by different manufacturers (such as Word and WordPerfect). In the system of networked PCS, employees can use the same version of the application that provides file compatibility. In addition, a person who is engaged in computer network need only one time to update the network application, they are available to all, rather than multiple times to update it on each individual computer.
- Training and support costs are too high. Training costs are constantly rising, and even those manufacturers who have been doing it for free, now prescribe a fee for training and support. However, if there are many different versions of hardware and software costs are becoming prohibitive. Application in computer network “standardized” version software allows you to reduce the number of applications used in your organization, and this, in turn, will reduce the range of support services that are needed by your users. If any application requires training, this training will be able to get more users (which also would reduce the costs per user).
Performance is reduced because of the downtime waiting for resources. Performance may significantly fall if users have to wait until they can access a particular resource. For example, a user must complete the current account on the computer to another worker was able to download your data and print any document or report. Another example: the employees of Department on work with clients cannot from your personal computer to access the history of a customer’s service, account information, trends in orders and other information in other systems throughout your organization. Therefore, clients must wait for a query to other departments. In computer network any Department can get all the information about the client. If you can access through the Internet, customers can more effectively seek the information they need, make reservations and receive assistance.
Of course, there are plenty of other grounds on which one can understand that you want to use the computer network. For example, the data is lost because some users do not back up files regularly (if ever do). The loss of time and productivity due to manual transfer of files (also known as the “network of transportation information at its two”, “sneaker-net”) using floppies or CDs can also be reduced through the use of the computer network. Computer networks can replace notes in notebooks or piles of papers, as well as those that cannot be ignored or not noticed. Computer network can be used as itself internally and be connected with other computer network (or even the Internet), providing communication and interaction on a global scale.
Author: Jaringan Komputer
Let’s To Know ‘What is social networking‘
Start getting to know the site like this: a man goes to the site of a certain category, it is easy to register and enter your personal data in order to learn and to not respond to others ‘ questions is “Yes, it’s my Friendster page -add me as a friend!”. Then, after these simple procedures can search on the site of their relatives, friends or acquaintances with whom people studied or worked, resting or just recently met. Also, it is possible to perform a people search by criteria such as hobbies or interests. These resources are created with the purpose of bringing people together.
In ten years ago, many people have created for themselves personal blogs, forums, on which they placed their photos, personal information, contact details, address, location, marital status, employment and occupation , etc. today, now is not necessary to make or create such a site, because social networks have gained rabid popularity and online. All simply elementary and visually understandable. You don’t have to learn any language programming to make a site for socializing and dating.
What are social networks?
The first thing that comes to mind is communication of different people by using status, personal and public messages. That is, in order to gather around one person a group of like-minded people with whom you can talk on an interesting topic. For example, you can find an old friends, you can find an old friend, classmate. Find people who will share with you a hobby, recreation or just talk about topics of interest.in high school. Find people who will share with you hobby, leisure or just talk on interesting topics.
Why do we need a social network
First of all, social networks need to communicate. That is, to find the right person or group of people and discuss topics of interest. For example, you can find a childhood friend, who parted ways. Or odnoklassnicu, which was in love. And you can find like-minded people. Butterfly collectors or fans of rare music, for example.
With social networks, there are lots of useful things and interesting features. You can download your favorite music or videos, to find out the latest news, photo albums, to organize and join interest groups, play games, recording important events and much more.
Author : Jaringan Komputer
Network Definition And Explanation of Computer Networks
The generic term of ‘network’ defines a set of entities (people, objects ,etc.) interconnected with each other. A network allows you to circulate immaterial or material l elements between each of these entities according to well defined rules.
Network (in English network): all computers and devices connected to each other. Note that two computers connected together to them constitute only a minimum network. Networking (in English networking): implementation of the tools and tasks to link computers so that they can share resources of the network.
Depending on the type of entity concerned, the term will be so different:
- Transportation Network: A set of infrastructure and allowing to transport persons and goods between various geographical areas
- Telephone network: infrastructure to circulate between several telephones
- Neural network: set of interconnected cells between them
- Crime Network : set of crooks who are in contact with each other (a crook cached usually another!)
computer network Definition: a set of computers connected through physical lines and exchanging information in the form of digital data (binary values, i.e. in the form of signals that can take two values: 0 and 1)
A computer network can serve several different purposes:
- The sharing of resources (files, applications, or hardware, internet connection, etc.)
- Communication between people (e-mail, discussion online, etc.)
- Cross-process communication (between industrial computers for example)
- The guarantee of the uniqueness and universality of access to information (network database)
- The multiplayer video game
The networks also allow to standardize applications, generally referred to groupware to qualify the tools allowing multiple people to work in network. For example e-mail and group agendas to communicate more effectively and more quickly. Here is an overview of the benefits of such systems:
- Reduction of costs through shared data and devices,
- Standardization of applications,
- Access to data in a timely manner,
- Communication and more efficient organization.
Today, with the internet, there is a unification of the network. Thus, the interests of the establishment of a network are multiple, whether for a company or an individual.
Similarities between different types of networks
- The different types of Computer networks usually have points in common:
- Servers: computers that provide shared users by a network server resources
- Customers: computers that access to shared resources provided by a network server
- Connection support: determines how the computers are connected in
An additional Application to face-to-face (webcam application) has been released by facebook into room links included are Video applications such as vChatter, People Roulette, Bando Chat, ChatVibes and Chat rounds which finally release end of 2011. This application comes with additional features such as the Calling person (without using headphones), as well as chat messager personal. However this application is still a lot of drawbacks which can only be used for the link to this application into facebook as well, and can only be used if the personal calling is being used/activated the application (Video Chatting). To enter the link and it’s application, Please log in to your facebook and register your identity, then it would be like the picture above.
How to use Android mobile phone as webcam
Today I’m going to tell you how to use the Android mobile phone as webcam “as many of us use and desktop in general do not have a webcam, so what if you want to make a video call, don’t worry you have Android Smartphone that will let you make a video call on your computer so there’s plenty of online applications available making Android webcam but the I’m going to tell you so easy.Let’s start it:
- Step 1: first of all install the webcam IP downloaded Android mobile phone, as well as to install the adapter IP camera on your computer.
- Step 2: open IP camera application which installed on your phone, then Setting up the options such as user name, password, screen resolution and many more which you can adjust according to your choise, after doing so just click Start Server.
Note: this app uses rear camera in better quality default enemy but you can also change the status of the front camera but it lowers the quality of your videos.
- Step 3: now when you click the start server , you will see the IP at the bottom of the screen of the laptop now open IP browsers chrome or Firefox for your laptop if none of these browser in your mobile browser and nstalled select Android’s built-in Viewer option.
- Step 4 open and install the downloaded IP camera adapter on your computer now in “enter address” only camera goes your IP and port you have the application installed on your phone and remember not to delete/videofeed and then click autodetect.
Step 5: now that your done to open any application in video conference calls on Skype, Facebook-like Messenger, Yahoo! Messenger and you will see the streaming video on your Android mobile phone.