Computer technologies greatly facilitate the life of mankind, and since we are talking about local networks, the specific application of a computer network is diverse, but the basis of everything is the simplification of familiar tasks. Local area networks facilitate many tasks in terms of transferring data within a company or in a private home network. This is what we will talk about today.
Advantages of LANs
Here you want to transfer a movie to a memory card of a tablet or smartphone, and you are too lazy to get up, but if you have a home local network, then you can easily use a video player that supports streaming using a local network, for example, VLC Media Player.
VLC Media Player you just need to start, select the "Stream" mode and calmly watch the movie without getting up from the couch, on another device, or through folder sharing, then you will need to select the local network in the program and the file, to open.
Or you are a business owner and you need all employees toworked with high productivity. You can constantly give them a scolding, but there will be more sense from highly qualified specialists if you provide them with modern technologies. Let's say you have a private enterprise for working with documents, any employee will get tired of dangling back and forth every time, and productivity drops. The local network will come to the rescue, with its help you can get rid of the "time eater" in the form of eternal running around between tables in search of the necessary information.
This is a small number of examples of LAN applications.
Let's look at the following concepts: local network, types of local networks, their advantages and disadvantages.
Computer network, it is also a computer or local network - a system for exchanging data between electronic devices, provided with transmission media. The latter can be optical fiber, radio waves, etc. Provides data transfer up to 10-15 kilometers between subscribers. Particularly useful when inside one large building or multiple adjacent buildings.
Pros of technology can be considered:
- Resource sharing is the rational use of devices within the network.
- Data sharing - access to files from other devices. Organize and share work paper and other files.
- Sharing applications installed on computers - using programs installed on neighboring computers.
Types of local networks
There are two models of localcomputer networks:
- Peer-to-peer network.
- Client-server network.
Start by explaining the first term.
In peer-to-peer, all information is shared between devices. Any user can change file permissions. The computers themselves serve as workstations.
Gives full access to any network user to any resources and device files.
- This type is easy to implement and affordable.
- Connect up to 20 devices (possibly more).
- Many devices - low performance (observed with old hardware and software).
- Lack of a unified infobase.
- Low security.
- Dependence of information on the state of the computer, i.e. if the device is turned off, then the information will be unavailable.
Client-server networks have only one main computer - the server. It stores information and processes it.
- Universal server - for simple tasks, data processing in the local network.
- Database server - processing requests sent to the database.
- Proxy server - connecting a local network to the Internet (VPN).
- File server - resource allocation and file access.
- Application server - execution of application processes.
- Mail server - answers to requests sent by e-mail.
- single information base;
- advanced security system.
- qualified service personnel needed.
Creating a local network
Hardware. The whole system is based on data transmission, so that they can be sent, the following devices are needed:
Network adapter - a board for transmitting and receiving information from the network. Computers can be connected using various cable types (fiber, twisted pair, coaxial).
Cable is the basis of a communication channel - the physical medium of data transmission. You should especially pay attention to the throughput (bps, kilobits/s, megabits/s, etc.). As an example, RJ45 cable.
- Hub - a device for transmitting a signal from one device to another. On average, 8 to 30 connectors (ports) for connecting a computer or other hub. Each port is dedicated to a different device. Due to them, the entire network works.
- Wi-Fi router is a device for wireless transmission of information that allows you to connect up to 10 devices. Suitable for home network or computer club. You can install many routers along with a router, then the network will be wireless, and the number of devices will be limited only by space and budget. Plus, you can connect external memory to the router.
Software. In addition to hardware, specialsoftware and setting up a computer or other device to work within the network:
- LAN capable system.
- Set up individual folders and data for external access.
All modern and older systems such as Windows XP support creating and accessing files on a local network. So the main search for network access programs is limited to individual devices, such as smartphones, tablets (not on Windows), devices based on the Linux kernel, etc.
The following varieties are distinguished:
- "Common bus" (bus).
- "Ring" (ring).
- "Star" (star).
- Physical "star" and logical "ring" (Token Ring).
Common bus topology.
Uses a single channel for data transmission over a cable (coaxial), termination resistors (terminators) are installed at the ends. Connection via T-connector. Information goes to all nodes, but only a specific one is accepted.
- Node failure will not affect the operation of the entire network.
- Easy setup.
- Stability in case of failure of individual nodes.
- Cable break affects the entire network.
- Restriction on cable length and number of workstations.
- Difficulty finding a defect in a connection.
All nodes are connected in an inextricable ring, which ensures the transfer of information. The transmission goes through every device on the network, from one point to another. Data moves in one direction.
The advantage is the ease of creation and customization. Among the disadvantages is that if the communication gap is damaged or the computer fails, the entire network will fail.
Topology of local networks "star".
Each PC or server is individually cabled to a hub or hub. The latter provides a parallel connection.
- Easy connection of new devices.
- Central management.
- Tolerance to failures of individual devices in the network.
- Failure of the repeater (hub) negatively affects the operation of the entire network.
- Need a lot of cable.
Token Ring topology.
Based on ring topology. The best topology, as it suggests that access is distributed evenly across all workstations and provides high reliability due to the resistance to discontinuities of individual stations. However, a very expensive option.
Classification of local networks is divided into just local and local extended networks.
Fields of application of local area networks
The following applications of the technology are known:
- Create personal localnetworks.
- Gaming clubs and LAN play with friends.
- Automation of management activities, organization of "electronic offices".
- Production automation.
- Learning automation.
Many types of local area networks can be hacked.
Since all computers are connected to one network with file sharing access to each other, it is likely that all this will allow any hacker to inject a virus, a Trojan into the network, which will spread to all computers and devices on the network (almost all) where there are security issues.
The same maintenance people can pose a threat to the company, because nothing really prevents them from influencing the network, especially if the server-client type system is not so dangerous for the peer-to-peer LAN option.
And you can do a lot:
- Steal all data, especially if they are not protected by anything and are accessible by the local network.
- Introduce a spy to investigate user activity.
- Where there are work computers, there are home ones. With a flick of the wrist, all malicious code will migrate to your home computer if no antivirus is installed on it.
- It is possible to stop network activity itself by causing a reboot.
- And much more.
So you need to worry about the security of the entire network.
Must haveuse anti-virus solutions from various companies, anti-spyware programs, monitor network activity, encrypt, apply DMZ creation - when a network fragment is not fully trusted, IDS - intrusion detection system, NAT - technology for translating one or more addresses to other addresses, firewall or Firewall, changing the file system to NTFS (for professionals), installing the latest system updates, not providing full access to employees on their computers, that is, delimiting their rights and administrator rights. Nobody usually needs a peer-to-peer local network, since they are used in schools and institutes, and there is nothing special to mine there.