What does a router do on a network? What additional protective measures are needed?

During the conference, questions often arise about setting up network storage devices and connecting multiple devices for collaboration. However, information for beginners is rarely provided in articles. With this series of materials, we decided to fill the gap and help users configure their equipment efficiently and conveniently. It does not claim to be exceptionally complete and deep, but we hope it will be useful to a wide range of users.

So, you already have a computer or laptop, but you decided that this is not enough and it’s time to get a few more interesting devices– wireless router, network storage, media player, IP camera. The idea is certainly not a bad one, but if you have only worked with one PC before, reading numerous instructions will take a lot of time. Yes, and it may require certain preparation. But in reality, it's not all that scary. Many devices have built-in “helpers” for quick setup, A network parameters often installed automatically.

General scheme

Let's start with a description of the participants and some general terms. We took the first illustration from the description of the ZyXEL NBG460. Here you can find a PC, network storage and printer, laptop, IPTV set-top box and a smartphone. The only thing missing is game console and media player.

It is the router (also often called a router) that ensures the connection of all devices into a single home local network and its connection to the Internet. Internet connection options may vary. For example, via Ethernet (“Internet Beeline”, Net-by-Net and others), via Wi-Fi or 3G/4G modem, via ADSL technology via telephone (“STREAM”) or via cable modem (“AKADO”). The last two options require a special modem. It can be made as a separate device with Ethernet port at the output or built directly into the router. In this case, the latter often has a corresponding prefix in its name.

The Internet connection port itself is usually called “WAN” - from Wide area network. That is, to connect to a “big” network. But the PC, network drive and other wired devices are located in the local/home network segment and are connected to the “LAN” ports ( Local area network). Depending on the router model, there may be a different number of them, most often four.

Except wired connections Using Ethernet technology, HomePlug can be used to connect devices - a network through standard electrical wiring or Wi-Fi - a wireless connection familiar to everyone (the combination WLAN - Wireless LAN is usually used to designate this network segment). They all differ in speed and other capabilities.

Note that to increase the number of wired ports (in some cases, the standard four may not be enough), you must use network switches. By installing an additional model with 8 ports, you connect one of them to the router, and the remaining seven remain for connecting devices. That is, the total number increases by six, since two ports are required to connect the router and switch. The switch can be either 100-megabit or gigabit. The second option can be used if you have a working network and a router with Fast Ethernet that suits the speed, but you want to ensure fast communication between your desktop PC and network storage without changing the router.

In general, today, if we talk about wired ports, then of course it is desirable to use gigabit connections as much as possible (especially if we are talking about a cabling project during a renovation). However, this will not directly affect the “Internet speed” in any way. The only place where a higher speed can be justified is the cable connection of high-performance devices (and there should be more than one of them) that require quick exchange large volumes information.

As for wireless communications, we would recommend buying routers today that support 802.11n technology, which, compared to 802.11g, shows 2-4 times higher results in performance tests and usually has better coverage.

For providers working via PPPoE/PPTP/L2TP and having a developed network of their own resources, it will be useful for the router to support simultaneous work on the Internet and access to the provider’s network.

A similar note concerns working with IPTV - if you require it, the router must support it. True, there are too many options for implementing the service and this question need to be clarified for each specific provider separately.

As for the general performance comparison in different modes connection, then depending on the model and type of connection, the user can expect speeds of up to 100 Mbit/s. Reviews on the site usually provide figures for test results in different modes (do not forget that with the release of new firmware they can change significantly).

In fact, the more significant issue when choosing a router is its compatibility with a specific provider. Unfortunately, it is impossible to answer this question with laboratory tests. In this case, we recommend that you turn to forums and recommendations from users of your network, but the most successful is to consider a purchase with the condition of testing the functionality in your specific apartment. The router option offered by the provider in this case has one undoubted advantage - if something does not work, the provider himself will deal with it. But they usually have a smaller selection of devices, the models themselves are less “interesting”, and the cost is higher.

Setting up the router

As an example, we use the ZyXEL NBG460N Internet center model, connected to the Beeline Internet provider. Before setting up any device of this class It is advisable to check on the manufacturer’s website for the availability of new firmware/firmware. Second important point– changing the administrator password to access the router.

We believe that the Internet itself is already configured on it. There are too many possible configurations to describe them here. We will mention only the main options:

• direct connection with a fixed or dynamic address (usually you need to change the MAC address on the external interface on the router or inform the factory provider);
• connection via PPPoE – username and password required;
• connection via PPTP/L2TP – requires specifying the address or server name, user name and password.

In particular, for ZyXEL equipment, the easiest way to configure is to launch the bundled NetFriend program, specify the region, provider name and account information. In a few minutes your Internet will be working.

What are the next steps to take? Perhaps the very first action will be to set up a secure wireless network. By default, routers usually have an enabled radio block with open network. This means that anyone can connect to it and not only use your Internet channel, but also possibly gain access to computers.

So we recommend changing the network name to something original and setting the mode to WPA2-PSK AES. This is the safest option today. And for 802.11n equipment only it provides maximum performance. You should use other options only if some of your wireless equipment does not support it. Also, do not forget that WEP cannot be considered secure today and that the password must be complex - one and a half dozen random characters. Possible difficulties with its input on mobile devices are compensated by the high level of network security. And for laptops and PCs you can use WPS technology For quick connection– you just need to press a button on the router and on the client and in a few seconds a secure connection will be set up.

To improve 802.11n performance, it is recommended to enable the “40” (or “20/40”) mode in the access point settings, which means operation on two radio channels. You can select the most free channel using inSSIDer programs, launched on a PC with a wireless adapter installed.

Typically the router has a DHCP server enabled. It “distributes” IP address settings to all devices connected to it. So there is no longer any need to specifically point out anything about them. Despite the fact that the system works automatically, we would recommend programming fixed MAC-IP matches on the router for those devices that will subsequently need to be accessed from the Internet. This is necessary so that their IP addresses are permanent and can be registered in the port translation rules.

Most often, the range of addresses that is used in home network– 192.168.0.* or 192.168.1.*, where “*” is any number from 1 (usually for a router) to 254. You can check the current PC address either in the network connection status or by typing ipconfig in command line(for Windows systems).

Recall that a MAC address is a physical/hardware identifier that any network device has. Often they are even written on packages and cases. Formally, they are all individual on a global scale, but in many cases they can be changed through the device driver settings. It is represented as six bytes, written in the format hexadecimal digits, for example 001020AABBCC or 00:10:20:AA:BB:CC.

The next point that is worth understanding is the permanent/external/white address. These concepts are often confused, so it is imperative to put things in order. If you use a router to connect to the Internet, its WAN interface has a specific IP address. All devices that are outside your home network see exactly this address and know nothing about yours. internal devices. The network address translation (NAT) technology operating in the router automatically and transparently for the user replaces internal addresses with external ones and vice versa when transmitting and receiving network packets.

In turn, this address, which is issued by the provider or required to be specified in the router during its configuration, can be permanent or dynamic. The only difference between these options follows from their names.

But of greatest interest is the question of the external/white address. These terms usually mean “an address accessible from anywhere on the Internet.” An example is an office PBX with a single external number. All its subscribers can communicate with each other by dialing an internal number. Outside the office, these numbers have no meaning. At the same time, they can call landline phones, but it is impossible to directly reach each specific subscriber simply by dialing a landline number. In turn, this office with its own PBX can be located inside an office building with its own PBX and another switch.

This example shows one of the reasons for using NAT technology - you can have a local network with Internet access of almost any size, but “waste” only one address from the general global list. With the transition to new version With the IPv6 protocol, this problem may disappear, but no one knows when this will happen.

It would seem that if the Internet works like this, then why might you need an external address? The answer to this question is quite simple - if you want to have access to your local network from the Internet, its use is necessary. For example, you are planning to create an FTP server, place a Web server with a family photo album on your PC, or you want to have access from the office to files at home network storage. Note that these problems can be solved in other ways, but they are much more complicated and more expensive.

How to determine which address your provider provided you with? First, you need to look at the external address of the router on the corresponding page of its Web interface, if it looks like 10.*.*.* or 172.(16...31).*.* or 192.168.*.*, then it is definitely “ grey" and it is impossible to access your network from the Internet using normal methods.

The second test that can be done is to go to the website and compare the address that this service shows with your address on the router. If they match, then you're in luck.

Many providers provide users with an external dynamic address. In this case, another problem arises - the address, although external, is not permanent and it is impossible to find it out while outside the network. To solve this, you need to use the dynamic DNS service built into most routers - it allows you to get a permanent domain name that will automatically be configured to the router’s IP address when it changes, and it can be used at any time to access your network.

You can use the DynDNS.org service completely free of charge - one domain name is provided to everyone. A working email address is required to register.

In addition to accessing the local network, an external address can be useful for improving the efficiency of certain services, such as messaging programs or p2p networks. Note that here we are only talking about the fact of the presence of an external address, and the use of DynDNS in this case is not required. However, there are some steps worth taking.

We are talking about broadcasting network ports. This is sometimes called "port forwarding" or "port opening". This setting allows an external destination to connect to specific program, which is located on your PC behind the router.

Please remember that connecting to network services occurs with the indication of the IP address and port number. For example, for HTTP it is 80, for POP3 it is 110, and so on. But if it's not about standard programs, then the numbers can be almost any (from 1025 to 65535) and often they can be specified in the settings of the program itself.

Configuring port translation allows you to transmit a request incoming to the external address of the router and to certain ports to a PC located in the local segment. For example, you can create a Web server on a PC and “forward” port 80 for it. Depending on the router model, external and internal numbers may differ or must be the same. It is also worth mentioning that some of the ports (most often 80, 8080, 23, 25) are blocked by the provider for security reasons. After setting up port translation, the program installed on the PC begins to behave as if it has a direct connection to the Internet past the router. Check the operation of port translation in the program itself, if such an option is provided.

You may encounter the “protocol” parameter when configuring port translation. We are talking here about two protocols within TCP/IP - TCP itself and UDP. In most cases, the first one is used for Internet communications. The need for UDP is usually indicated in the program descriptions. If the router does not have such a parameter, then both protocols are broadcast at once.

Some programs support the UPnP protocol to automatically open ports for themselves. However, from a security point of view it is better not to do this, since “simplicity” has its own reverse side– lack of access control.

In some cases, it will also be useful to set up regular sending of log files of the device’s operation to your address at email. The truth here is that you need to understand that if there is no Internet connection, then nothing can be sent to an external server. To correctly display the date and time in the logs, the router has a built-in clock that can be synchronized via the Internet.

Another rather rarely used option is allowing access to the Web interface for configuring the router from the Internet. This should be done only in case of emergency and do not forget to really install complex password for access.

Total for at the moment we have:

• router connected to the Internet;
• secure Wi-Fi network;
• service for distributing addresses on a local network;
• configured DynDNS for accessing the network from the Internet;
• translation of ports for running services on a PC or other devices.

In the next article we will talk about setting up network storage drives.

A router (router) is network device, necessary to redirect data packets in one or more subnets using one or another principle. The router can analyze the data, determine the destination and select a route based on the information received. In part, the device resembles a computer, which, in general, is so. If a switch (switch) can create a local network between several computers, then a router can connect several networks simultaneously, with different IP addresses.

It’s interesting that if the first models of routers could determine routes only based on the information provided by the administrator, then modern models capable of automatic mode analyze technologies and current performance, determine traffic priority classes, build short routes, etc.

Please note that there are professional routers that work in large enterprises and are capable of supporting a huge network, up to entire cities. There are also more compact routers, which are used to create a network and distribute traffic in an apartment or company office.

Why do you need a router?

There are actually many reasons. Here are the main ones.

• Creation and unification of the network. For example, as in the example of a company office, where the administrator can have access to each of the computers.

• Internet connection. You can connect to the Internet directly (using a cable), or through a router. This method will also allow you to distribute the Internet (see the next point).

• Internet distribution. Actually, this is the main reason why routers are purchased for the home: they are capable of distributing the Internet to computers or other devices.

• Protecting your home network from online threats.

• Traffic control and prohibition of visiting certain resources.

How the router works

As for the operating principle of the router, it is quite simple, but if you start using various terms, I’m afraid you won’t understand anything. Therefore, I will try to explain everything in simple words.

Data on the Internet is transmitted using packets. Each package contains a delivery address. When a router receives a packet, it finds the address that is specified in the packet and sends it over specified address using one method or another. That's it in a nutshell.

Router appearance

Everything is simple here - most of you have probably seen routers, and many have them in their apartments or offices. It is usually a small device with a specific design. Since routers are usually in a visible place, designers try to embellish the device.

On the front side of the case there is usually nothing except indicators, of which there can be quite a few, for example, more than 10. On the front side there may sometimes be a button to turn the device on and off.

The back side is much more interesting. Here we can see a lot of interesting things.

• Antenna, if the device has one at all.

• Connector for power supply.

• Power button, if available.

• WAN port, which is used to connect to the Internet.

• LAN ports. Their number can be very diverse, but for small routers their number rarely exceeds 8 pieces.

• (Reset).

• Some models have a USB port.

It is worth noting that routers for home use very popular today. Not least because of their cost - some models can be purchased for less than 1 thousand rubles, professional ones are several times more expensive. Users experience the main problems when setting up a router, since all these numbers and letters that must be entered into the device interface can shock an unprepared person. Fortunately, they are being released today special firmware, which are used to configure the network for a specific provider. In addition, at the provider’s office, setting up a router is usually free of charge.

Router (router) is an electronic device that forwards network data packets between segments, guided by certain rules. Home often simply separates two domains. Local network IP addresses are invisible from the outside. Formally, the router sets the direction of traffic. Gradually the packet reaches the destination.

Organizing complex, branching topologies for economization and increasing speed requires filtering the moving flow of information. Because the Ethernet protocol by and large broadcast. Imagine: a request to a search engine would be broadcast to everyone, to all earthlings who turned on their personal computer. Formal DDoS attack. This state of affairs will greatly reduce the efficiency of the Internet, practically reducing the speed to zero. Routers protect communications against such collisions.

Purpose

The router is designed to relieve network traffic by thoughtfully sending messages. Further optimization is carried out by a well-thought-out policy of the administrator and the software of the router itself. Details are provided below.

The professional definition says: a router implements the third (network) layer of the OSI protocol. Unlike:

• Switches (level 2).
• Concentrators (1st level).

Operating principle

The device receives the packet, decrypts the address, and, if necessary, replaces the specified field in accordance with the requirements of the network segment where the target PC is located. For example, the local combination 127.0.0.1 is clearly not accessible from outside. In order for the packet generated by the server of a real website to reach the browser, the hardware will carefully determine the route and insert the required numbers. The substitution rules are briefly described:

1. Routing tables.
2. Routing policy.

Household scrap metal simply pushes packages (forwarding). The core of enterprise hardware solves more complex problems. The presence of heterogeneous routers communicating with the network will require the creation of a packet conversion protocol. Each builds a routing table containing the preferred paths for transmitting traffic between any two subsystems. Network elements are usually divided into 2 planes:

1. Control - draws the network topology, or contains a table showing the processing order of each type of incoming packet. Each function of the plane is implemented by a dedicated architectural element. For the most part, the table contains destination addresses broken down by port. Directives for constructing a route can be specified in advance (static) or generated by the protocol (dynamic). The information is saved. Elements that have lost their relevance are gradually cleared out, and a database is built for the functioning of the forwarding plane.
2. Forwarding – deals with the forwarding of packets between input and output ports. Sometimes structures have to be transformed according to the topology. The table formed by the control plane helps to perform the necessary operations.

Static addressing

Typically, static routing is assigned by a human. The installer enters network address values ​​using the equipment configuration interface (address 192.168.0.1 and so on). The administrator fills out the table himself (not always). A tangible disadvantage is the inability of the equipment to track current changes in the network configuration. Static routing does not exclude dynamic routing; rather, both complement each other’s functionality.

In addition to the home-grown principle of using a browser, a professional admin is endowed with knowledge of other ways to set settings. The professional interface is designed to simplify the function of updating databases at the corporate network level.

Advantages

• It’s easier to set a fixed route that cuts off unnecessary device ports. Brings orderliness to communications.
• Ideal for small networks using 1-2 routes. Eliminating dynamic table generation traffic greatly improves performance.
• Sometimes routes are statically set in case of failure, ensuring uninterrupted operation of the network.
• Nonsense, but fixed paths are often a reliable means of distributing protocol information.

A list of routes generated in advance significantly relieves the router processor. The administrator gets full control.

Flaws

• Human factor. On purpose or intentionally, the operator is capable of disrupting the operation of the equipment.
• Inability to handle failures. If the equipment breaks down, the delivery of packages is completely disrupted. You'll have to wait for the problem to be fixed.
• Dominance is common static addresses. The above may disrupt the operation of protocols. The administrator can easily correct the problem by changing the distance in the equipment settings.
• The complexity of the configuration change process. The administrator has to manually make adjustments. The process sometimes takes a long time.

The conditions for promoting the package are determined by the current prevailing conditions. The setup is done automatically. Flexible adjustment of databases helps “surviving” routers continue to do their work, and users continue to enjoy the benefits of civilization. In simple words:

• Dynamic routing is automatically implemented by the equipment, maintaining the functionality of even a damaged, sometimes failed network.

It is worth mentioning the original purpose of attempts to link computers together. The American military assumed the failure of some combat computers. The purpose of communications is to preserve opportunity effective management line of air defense even in such barbaric conditions. Skynet from Terminator is not entirely fiction (as is commonly believed)…

We believe that dynamic routing became the first in evolution. However, the veil of military secrecy hid the details of the implementation of the algorithms.

Protocols

A special protocol helps transmit information from a router to a neighboring one. Several of them have been developed (a tribute to competition).

1. RIP implements a distance vector algorithm (devoid of loop traffic). The package gradually, jerkily overcomes the route.
2. OSPF ( structural part IGP is a shortest path protocol using Dijkstra's algorithm. Builds a graph and calculates the shortest distance.
3. IS-IS calculates the best way in packet switching networks.

More often, the router decides on the fly the further fate of the packet. Constant search and optimization lead to the emergence of improved protocols, such as the main tree algorithm, which helps eliminate cycles and loops. The neighboring branch is unavailable while the current one is operational. The group adaptation algorithm provides for forwarding to a currently free port. Link aggregation is effective for link traffic that is split into narrower bands.

Typical Applications

In addition to computer networks, the technology is widely accepted by specialists. Flexible adjustment helps to study neural processes and provide passengers with the latest news about trains and planes. Financiers love instruments that reliably reflect the rates of securities and currencies.

The correct use is considered dynamic routing for building contact centers. The measure makes the operator independent of the router and cable integrity. The entire system works better, there are fewer refusals, and the call reaches a free operator. Omnichannel is achieved.

Routing table

The IP address database is stored by the router or local PC. Inside there are ready-made paths for recipients, using which the processor selects desired port sending. Sometimes the data is supplemented with route distances (a conditional value for the duration of the transmission process). There is certainly information describing the topology of adjacent segments. It is the formation of routing tables that is the main goal of the functioning of routing protocols.

• The routing table is a repository of information entered by the administrator or protocols about the paths of packet transmission.

The postal principle is used. Like a person choosing a forwarding address, the equipment is able to correctly determine the direction of travel of data packets. If it is impossible to immediately deliver the message, the router begins to choose the optimal path of movement. The parcel is handed over to the recipient step by step.

Along the way, the dynamic system learns by adding to the table. The information is stored in local RAM. The size of the chips is limited. A typical database contains:

Forwarding information base

The forwarding table is often called the MAC. Information helps you choose a device correct port movement of information. The card matches the MAC addresses of network cards and router interfaces. The base forms the main difference between switches and hubs. Since addresses are often stored in associative memory, tables are also called CAM (according to the Latin abbreviation).

A router stands slightly higher than a switch because it can take into account the topology of segments. However, the forwarding table functions in a similar way. Without it, the device will become a hub and will forward the received packet to absolutely all ports. Associative memory maps real MAC addresses of computers to output interfaces. This significantly speeds up the shipping process.

The router dynamically learns numbers by receiving packets. An example is ARP (Address Resolution Protocol).

Above layer MAC data meaningless. The exception is Ethernet bridges. Devices operating with higher OSI levels, are actively engaged in frame relaying, use asynchronous transmission, and multi-protocol label switching. Examples:

It is considered good style to check the truth of incoming packets - compliance of the current header parameters with those declared by the original network or site. However, a pile of information greatly clogs the router’s memory, significantly complicating the practical implementation of the concept.

So far, IETF documents have refused to address pirate attempts to tamper with resources. Adding to the difficulties is the desire to duplicate the channel by connecting several providers - a typical corporate option.

It is the forwarding table, where the IP addresses are located, that becomes a frequent target hacker attacks"intermediaries". Attackers are eager to redirect traffic in the desired way.

Design, characteristics

Let's call the main component visible from the outside the ports. Today the link layer interface can be of the following nature:

1. Cable.
2. Optical fiber.
3. Wireless Wi-Fi.

The difference is significant: the configuration of the optical connector bears little resemblance to a typical RJ-45 Ethernet. It looks different, but the fundamental difference is the frequency of the transmitted signals. The optics need an LED. It is the high frequency that distinguishes fiber from cable.

The device supports a fixed set of network technologies. Most often - the usual Ethernet. Many devices also support subnets that differ in prefix. Typically, the topology of providers resembles a tree.

Each level corresponds to a fixed set of functions. Therefore, it is useless to take Juniper PTX home. Complex equipment is more suitable for a large corporation. Similarly, there are models aimed at meeting the needs of providers. Therefore, inside enterprises, an attentive eye will notice equipment of almost any level.

Typical Features

Previously, there was a backbone of the Internet, but today the topology has become so blurred that it is difficult to thoroughly trace the purpose of the equipment.

Story

The foundations of the concept were laid (1966) by Donald Davis, constructing the British NPL network. The technologies were quickly adopted by the Americans, seeking to build a coherent line of defense (ARPANET). The IMP (Interface Message Processor) board acted as a network node that switched messages. The design lasted until the collapse of the USSR, and was abolished in 1989, forming the first generation of gateways, which became evolutionarily routers.

The early swallow was a shock-proof Honeywell DDP-516 minicomputer, complemented by a special external interface communications. Some of the switching functions were given to software. Subsequently, the role of switches was given to Honeywell 316, which was deprived of special protection. Newbies delivered about two-thirds the performance while costing half the price. The connection to the hosts was made using serial bus data transfer. Hardware, Software discusses open source (now) RFC 1, the first one issued by the IETF.

Understudies

Historians describe the process in a curious way. According to the data, in 1967, the creators of the American network gradually came up with the idea of ​​​​introducing a dedicated computer to solve the problem of sending data packets. Wes Clark proposed inserting a “small computer” between powerful defense PCs and the highway. Had the participants created the sketch, they would have quickly realized that a single module would be enough to unite the brain sections of the US air defense into a functioning defender of democracy.

However, scrupulous historians mention the fact of the visit of British engineers to the USA (that year). The creators of the defense network clearly learned about the work of their colleagues overseas.

On stream

Mass production (1969) was undertaken by BBN. The government has ordered four interface modules. The release of the first was timed to coincide with Labor Day, the subsequent ones were shipped at monthly intervals in turn. The team was solid:

• Director: Frank Hart.
• Programmers: Willie Krauwer, Dave Walden, Bernie Kozel, Paul Wekselblatt.
• Circuit designers - Severo Ornstein, Ben Barker.
• Theory and Integration - Bob Kahn.
• Support Staff - Hawley Rising.
• Later, the team was supplemented by Marty Froup (circuit designer), Jim Geisman, Truth Touch (adjusters), Bel Bertel (Honeywell representative).

Programmers started in February 1969, customizing the code for the DDP-516. The final code was 6000 machine words, written in assembly language. The debugging environment was run on a PDP-1. The principle of operation of the machine was repeated by a modern messenger. The board received the message, the PC saved it, then broadcast the message to the recipient, eliminating collisions.

BBN only finished the IMP driver; the task of combining the four machines together was left to future generations. The software included an error control mechanism. Failed packets were immediately destroyed and the sender was notified. The reliability assessment factor was a 24-bit checksum. The addition was carried out in hardware, since it was necessary to satisfy the speed indicators.

Initially, IMP was served by a single host, then several began to be connected. The first interface was delivered on August 30, 1969 to Leonard Kleinrock (UCLA). The host was the Sigma-7 computer. The second went to Stanford research institute October 1, starting to service the SDS-940. The third was installed at the University of California, Santa Barbara on November 1, and the fourth at the University of Utah a month later.

Test run

The test of the first two interfaces took place on October 29. Historically, the first word “login” transmitted by machines was interrupted at the third letter. The bug was fixed with lightning speed, and a successful transaction followed a few minutes later.

BBN developed a benchmark program that measures performance. During the 27-hour period of mutual activity of UCSB-SRI computers, the system made an error approximately 1 time per 20,000 packets.

Second generation

The next version (Honeywell 316) was able to connect terminals to computers, allowing the total processing power to be divided between several tasks and groups of researchers. However, the second generation (1972) started with the release of BBN's IMP Pluribus. In fact, the hardware seemed like a miniature version of Honeywell.

Interface PCs served until their complete disbandment (1989). Some of the machines began to serve MILNET, others went to decorate the shelves of museums. Kleinrock put the very first interface on display at UCLA.

First protocol

The first host-to-IMP protocol, called 1822, is considered the predecessor of OSI, predating its modern equivalent by 10 years. Therefore, 1822 does not directly fit into today's realities, but it included the physical, data link and network layers.

Addressing was carried out in numbers, reminiscent of modern IP. But the IMP mutual communication protocol served as the basis for the creation of routers. Maximum length the information part was 8159 bits, 96 were allocated to the header. Modern packets are sometimes lost, whereas a defense network was guaranteed to deliver the message.

First router

After the first successes, some of the technologies became civilian. The developments of the Xerox company (1974) did not receive due recognition. Therefore, Ginny Stracisar (BBN) is considered the inventor of the first router. The module became part of the DARPA complex (1975-1976). Finally, three routers based on the PDP-11 served the experimental Internet prototype. Two people created multiprotocol routers in parallel (1981):

1. William Yeager (Stanford).
2. Noel Chiappa (Massachusetts).

Since then, networks have used the TCP/IP protocol stack, but multiprotocol models have remained relevant, for example, models supporting IPv4, IPv6. Personal PCs developed precisely as routers. The 80s brought the world a real boom in digital technology. What started with cassette recorders ended with the introduction of the first personal computers. The world famous corporation CISCO took a running start.

This is a combined device used at the household level to create a home or office local network with access to world wide web for all connected PC devices. This is a kind of highly specialized mini-computer. Performs logistics and security functions.

More to the point in simple language- this is a device that independently, without additional commands, makes decisions about sending various packages (this can be files - movies, games, documents, and the Internet) between computers connected to it.

These devices are different, but the standard switch is a compact device with a built-in antenna, itself hardware unit, cord and power.
Example:

The main thing is not to confuse them with switches - these are two different things. Let's look at the difference between a router and a switch. Using a switch, you can only create a local area between several computers.

Since all devices that connect to the switch must have the same subnet IP addresses. A router can connect several similar networks together, with different IP addresses.

Story

Their history is inextricably linked with the history of the Internet. The first router was created in 1974, and since 1976, the prototype of the “World Wide Web” has emerged from three local networks with three routers.

There are different levels:

• edge - these are subscriber and edge tag devices;
• interprovider;
• network core routers.

Appearance

The router is an external device; the manufacturer takes its design seriously; it can be chosen to suit every taste. However, there are design points common to all.

From the back they look like this:

The last 4 points are variable and may not be available on all models.

On the front side there is a panel with indicators.
There may be wall mounts on the bottom side.

Why do you need a router?

The idea of ​​combining local networks into a single global network implies creating a way for one of them to find the other. Thus, you can compare the device data with a dispatcher at the gate: he determines who, where and on what route to leave, and also checks the invoices of those entering.

It is needed if:

• several computers need to be combined into shared network, for example, create a computer class;
• You need to distribute the Internet to several computers or devices.

He can also:

• establish a connection and connect computers to the Internet. (you must first have a cable/adsl modem that is connected to the Internet through a local provider)
• protect home or working group from various external threats.
• distribute IP addresses.
• control and encrypt traffic.
• regulate access to the network of users and visited resources.

If you bought a router and don’t know how to configure it, then it’s best to contact a specialist.

Incorrect settings can lead to equipment failure and signal loss, but if you know English (since the menus of many switches are almost always entirely in English) and want to teach yourself, then this instruction will help you understand the principle of operation and answer many questions.

Video: Wi-Fi router - what is it

Operating principle

Routers are installed at the boundaries between networks. For the internal one, routing tables are used, for the external one, protocols are used, according to which the optimal traffic of information packets is automatically distributed. Protection and control are carried out at the same time.

The principle of operation of the router is quite simple, but in order to understand everything thoroughly and without errors, you need to study scientific works and various books on network technologies. We will try to simplify the description as much as possible so that you can understand the principle of operation of the router.

Absolutely all data on the Internet is transmitted in small, small portions - packets, and in order for them to reach the desired address, at the beginning of each packet the delivery point (the address itself) is marked. The router performs the function of a postman, it receives the packet, uses the internal routing table to find the desired address (which is indicated in the packet), and it is sent further in the manner specified in the table.

Types and purpose of modems

Routers are produced with different modems, since the connection can occur through different channels.

1. modems dsl – adsl, vdsl. Used if internet services are provided via telephone wires;
2. cable modem Designed for cases when the provider connects the subscriber using its twisted pair cable;
3. fiber optic cable, or optical fiber. Separate routers are produced for it;
4. a leased line uses its own type of modems;
5. mobile broadband. A 3g modem with a SIM card slot is used.

Technical progress does not stand still and today on store shelves you can find various types of routers, namely:

• automotive– many buses and minibuses have wi-fi for passengers. Through a 4g or 3g modem we get access to the Internet, and with the help of a car router it is distributed to all passengers.
• for home group– special switches for the home that do not have unnecessary settings and others do not need lotions. Maximum simplified and easy to use.
• professional– for large companies in which it is necessary not only to connect several computers into a network and distribute the Internet to them, but to combine several networks into one group, and combine them with another group of networks.
• industrial– work in more difficult conditions. They are protected by a strong casing, operate over a wide temperature range, and their components undergo more stringent selection.
• for fiber optics– for high-speed Internet using GPON technology.
• broadband– for connecting several computers to high high-speed Internet without loss of speed, as well as dividing the local network into several segments.

Functions and operating modes

New products are equipped with increasingly powerful processors and high-tech systems, which makes the router work better and faster.

The router combines several devices:

• network switch;
• point wireless access to the network;
• router;
• firewall;
• A device that supports the Network Address Translation Protocol.

How it works can be understood by taking a closer look at its functions.

• network functions.
• Through the switch, office equipment “sees” each other and can interact. Thanks to the DHCP server, the router constantly scans the network and assigns each member a temporary IP address for internal use, which facilitates and speeds up the process of exchanging data packets.
• the external IP address received from the provider is converted into a set of local addresses for its specific network. What does it mean to have free access to the web from every connected device?
• at the same time, through the settings, you can limit the time and addresses of sites visited separately for each network participant.
• The switch is located first on the network, this allows devices to access the Internet autonomously. You can turn off wireless Internet, while wired devices access rights will remain.
• wireless connection. Since wireless wifi connection uses radio waves, then the presence household appliances nearby (for example, microwave oven, radiotelephone) creates interference. Therefore, dual-band, and even tri-band routers have appeared, using several radio wave bands in their work.

Large radius Wi-Fi operation depends on:

Photo: signal attenuation depending on distance

1. functions firewall implements a built-in firewall and firewall. this is camouflage (protection), blocking attacks and leaks. additional security is provided by encryption using wep, wpa, wpa2 technologies;
2. making calls via the web. using a switch you can connect analog telephone sets to the local area and make parallel phone calls via the Internet;
3. backup channel. modem is used cellular networks, if the main port external connection suddenly passed out;
4. print server. This feature allows you to install printer, scanner, or multifunction device drivers on the switch processor. thus, the “print” function becomes available to all devices on the network;
5. “repeater”-repeater mode. used to amplify the signal, capable of expanding the coverage area;
6. torrent client. may be built-in. but you can install it yourself. makes it possible to download files from the Internet.

Thus, using a switch, you can create a local web, give it access to the Internet and protect it from external threats. This is their main function. The differences between routers are related to the technical options for connecting to the Internet, the standards used, as well as additional functions and requirements.

Having looked at the characteristics of routers, we can summarize the parameters that should be taken into account when choosing a given device.

• If you need to organize a Wi-Fi zone, then you need to choose a router with this function.
• Find out what method your Internet connection is made of and consult with your provider about the technical characteristics of a suitable router.
• Be sure to pay attention to the wireless standard. It makes no sense to purchase a powerful device if the Internet connection speed is initially low. And vice versa. Your speed tablet will freeze if the router is of a lower wireless format.
• For professional activities, you definitely need a switch with advanced capabilities.
• Based on your needs, using a router you can even organize a Wi-Fi bridge between your home and your dacha, for example. Can be arranged wi-fi zone on an area of ​​up to 2000 sq.m, if you correctly position the switch and amplify the signal.

• other things being equal, choose a device with a USB port. This is the ability to connect additional external devices, for example, a network drive.
• If you decide to mount the router to the wall, be guided by the level of the computer desk.
• The further you are from the antenna, the slower the speed. The more wireless Internet users there are, the slower the speed. Take this factor into account.