Purpose and structure of global networks. Organization of complex connections in global networks

The history of the development of global networks 1964 USA. A computer system for early warning of the approach of enemy missiles has been created. The first global non-military network ARPANET was created It had a scientific purpose and united computers of several universities for a year. The World Wide Web (WWW) service was created - the World Wide Web.

Every computer connected to the Internet must have its own address, which is called an IP address (IP = Internet Protocol). An IP address is made up of four numbers separated by periods; each of these numbers is in the range 0 ... 255, for example:

How the Internet works The Internet uses packet data transmission. For its work, the TCP / IP protocol is responsible - the transmission control protocol. According to the TCP protocol, the transmitted message is split on the sending server and restored to its original form on the receiving server. The purpose of the IP protocol is to deliver each individual packet to its destination.

Network addresses Physical address (MAC address) - unique 48-bit code of the network card (in hexadecimal system) E9-41-AC-73 IP address - computer numerical address (network number + computer number on the network): Subnet mask determines which computers are “visible” on the same subnet; when superimposed on an IP address (logical AND operation) gives the network number FF.FF.FF.0 network number, computer number 48

Network addresses Gateway - the address of the computer through which packets go to other networks (to the Internet): DNS server - the address of the computer where the requests for converting the domain address to the IP address go: WINS server - the address of the computer where the requests for conversion go computer network name to IP address.

A document address on the Internet (URL = Uniform Resource Locator) consists of the following parts: protocol, most often http (for web pages) or ftp (for file archives) protocol, most often http (for web pages) or ftp (for file archives) signs: //, separating the protocol from the rest of the address signs: //, separating the protocol from the rest of the address domain name (or IP-address) of the site domain name (or IP-address) of the site directory on the server where the file directory is located on the server where the file is located file name file name it is customary to separate directories not with a backslash "\" (as in Windows), but with a forward "/", as in UNIX and its "relatives", for example, in Linux, an example of an address (URL) here the protocol is highlighted in yellow, white is the site's domain name, blue is the directory on the site and green is the file name

Task IP address Subnet mask Determine the number of the computer on the network

Solution IP address Subnet mask Bitwise conjunction is used - logical operation "AND"; Conclusion: the number of the computer on the network is 48.

The Subnet Mask task is a 32-bit binary number that identifies which part of a computer's IP address refers to a network address and which part of an IP address identifies a computer's subnet address. In the subnet mask, the most significant bits assigned to the computer's IP address for the network address are set to 1; the least significant bits assigned to the computer's IP address to the computer's subnet address are set to 0. For example, the subnet mask might look like: () This is means that the 19 most significant bits in the IP address contain the network address, the remaining 13 least significant bits contain the address of the computer on the network. If the subnet mask and IP address of a computer on the network, then the serial number of the computer on the network is _____

Solution Let's perform a bitwise conjunction above, the zero bits of the mask and the corresponding bits of the IP address, which determine the number of the computer in the network, are highlighted in white: = 12 Answer: 12.

The Subnet Mask task is a 32-bit binary number that identifies which part of a computer's IP address refers to a network address and which part of an IP address identifies a computer's subnet address. In the subnet mask, the most significant bits assigned to the computer's IP address for the network address are set to 1; the least significant bits assigned to the computer's IP address to the computer's subnet address are set to 0. For example, the subnet mask might look like: () This is means that the 19 most significant bits in the IP address contain the network address, the remaining 13 least significant bits contain the address of the computer on the network. If the subnet mask and IP address of a computer on the network, then the serial number of the computer on the network is _____

Slide 1

Slide Description:

Slide 2

Slide Description:

Slide 3

Slide Description:

Slide 4

Slide Description:

Slide 5

Slide Description:

Slide 6

Slide Description:

Slide 7

Slide Description:

Slide 8

Slide Description:

File Transfer Service The File Transfer Service FTP transfers copies of files from one Internet site to another using FTP (File Transfer Protocol). It does not matter where these nodes are located and how they are connected to each other. Computers that have shared files are called FTP servers. For example, to download the file cute4232.exe from the GlobalScape file archive ftp.cuteftp.com, you need to specify the URL of the file. When specifying a URL, the FTP protocol is written as ftp: //. As a result, the URL takes the form: ftp: //ftp.cuteftp.com/pub/cuteftp/cute4232.exe and consists of three parts: ftp: // - access protocol; ftp.cuteftp.com domain name of the file archive server; pub / cuteftp / cute4232.exe is the file path and filename. WWW-World Wide Web World Wide Web (WWW) - hypertext, or rather, hypermedia information system for searching for Internet resources and access to them.

Slide 9

Slide Description:

Hypertext is an information structure that allows you to establish semantic connections between text elements on a computer screen in such a way that you can easily make transitions from one element to another. Hypermedia is what you get if you replace the word "text" with "any kind of information" in the definition of hypertext: sound, graphics, video. The WWW system is built on a special data transfer protocol called the HTTP HyperText Transfer Protocol. WWW-pages - hypermedia documents of the World WideWeb system. They are created using the Hypertext markup language (HTML).

Slide 10

Slide Description:

Slide 11

Slide Description:

Slide 12

Slide Description:

Web site development tools A Web site is a collection of hypertext documents that are treated as a whole and are identified by a single URL address. You don't need to know HTML to create a website. There are many available visual HTML editors, their other name is WYSIWYG-editors of the mountain, allowing you to create sites without knowing this language. WYSIWYG stands for What You See Is What You Get - what you see is what you get. These editors work with visual forms, not tags. For example, to make the font of the text bold, you just need to select this text and press the corresponding button in the editor menu. After that, the editor will insert the necessary "l" tags into the HTML code, and the site developer will see the final result on the page. Visual HTML editors: 1. Adobe Dreamweaver is one of the most popular commercial software products for website development. It was originally developed and supported by Macromedia (until 2005). The following versions, starting with Dreamweaver СSЗ (2007), are released by Adobe. The editor contains a huge selection of all kinds of tools, a user-friendly interface, fine settings that allow you to tailor the program to the needs of the web-master, as well as a built-in FTP manager for uploading files to the server. 2. Microsoft Office SharePoint Designer 2007 - visual NTML editor and web-design program from Microsoft. It is one of the components of Microsoft Office 2007, but it requires a separate installation. This package is one of the fairly complex editors that allow you to create not only the simplest web pages, but also full-fledged web sites designed for the collective work of users. A newer version of Microsoft Office SharePoint Designer 2010 is maximally tied to the collaboration of a large number of people on one project, which requires the installation of the appropriate software on the server where the project is stored. 3. WebPageMaker is a simple, fast and convenient editor for creating websites. The user with the help of the mouse drags pre-prepared texts and graphics to the necessary places on the page. The program includes a large number of ready-made templates that can be used as a basis for a future site. 4 . Nvu is a free visual HTML editor. The advantage of the Nvu editor is that it is cross-platform: there are versions for Linux, Microsoft Windows and MacOS. 5. KompoZer - a fork of the editor Nvu.KompoZer is a free web authoring system that combines a web file manager and a visual editor. Compared to Nvu, KompoZer generates shorter markup code. KompoZer is extremely easy to use, which makes it attractive for users who want to build websites without serious technical knowledge. KornpoZer can be considered as an editor for creating small web projects.

Slide 13

Global networks Wide re Networks WN, which are also called territorial computer networks, serve to provide their services to a large number of end subscribers scattered over a large territory within the region of the region of the country of the continent or the entire globe. Typical subscribers of a global computer network are local networks of enterprises located in different cities and countries that need to exchange data with each other.

If this work did not suit you at the bottom of the page there is a list of similar works. You can also use the search button

Lecture number 27

Topic: Global networks

1. CONCEPT OF THE GLOBAL NETWORK.

Global networks (Wide Area Networks - WAN), also calledterritorial computer networks, serve in order to provide their services to a large number of end subscribers scattered over a large territory - within a region, region, country, continent or the entire globe.

Typical subscribers global computer network arelocal networks of enterpriseslocated in different cities and countries that need to exchange data with each other. Individual computers also use the services of global networks. Large mainframe computers typically provide access to corporate data, while personal computers are used to access corporate and public Internet data.

Global networks are usually created by large telecommunications companies to provide paid services to subscribers. Such networks are called public or public ... There are also concepts like network operator and network service provider.

Network operator is the company that keeps the network running smoothly.

Service provider (provider ) - the company that provides paid services to network subscribers. The owner, operator and service provider can be combined into one company, or they can be from different companies.

Types of territorial networksinformation transfer:

• Telephone;
• Telegraph;
• Telex.

In global networks, the following are used to transfer information.types of commutation:

• circuit switching(used when transmitting audio information over ordinary telephone lines);
• message switching(used mainly for the transmission of e-mail, teleconferences, electronic news);
• packet switching(for data transmission, recently it is also used for transmission of audio and video information).

Global computing networksare computer networks that unite local networks and individual computers that are remote from each other over long distances. The most famous and popular global network is Internet , worldwide non-profit network FidoNet, CREN, EARNet, EUNet, corporate, etc.

WAN subscribers can be LANs of enterprises, geographically distant from each other, which need to exchange information with each other, as well as individual computers can use WAN services to access both corporate data and public Internet data.

All Internet services are based on the client-server principle. All information on the Internet is stored on servers. The exchange of information between network servers is carried out viahigh-speed communication channels or highways.

These highways include:

• allocated telephone analog and digital lines,
• optical channels communications and radio channels,
• satellite lines communication.

Servers connected by high-speed backbones make up the basic part of the Internet.

Individual users connect to the network via PCs of local ISPs, ISPs, with a permanent Internet connection. Regional provider, connects to a larger national-scale provider with nodes in different cities of the country.
The networks of national providers are united in the networks of transnational providers or first-tier providers. United networks of first-level providers make up the global Internet

2.TYPES OF GLOBAL NETWORKS

Depending on the components, corporate networks built using:

• dedicated channels;
• channel switching;
• packet switching.

2.1. Dedicated channels

Dedicated (leased) channels can be obtained from telecommunications companies that own long-distance channels or from telephone companies, which usually lease channels within a city or region.

Leased lines can be used in two ways.

1. Building with their help a territorial network of a certain technology, in which leased leased lines are used to connect intermediate, geographically distributed packet switches.

Connection by leased lines only of interconnected local networks or end subscribers of a different type without installing transit packet switches operating using the global network technology.

2.2. Circuit-switched wide area networks

The advantage of circuit-switched networks is their prevalence, which is typical especially for analog telephone networks.

The disadvantage of analog telephone networks is the low quality of the composite channel, which is explained by the use of outdated telephone switches operating on the principle of frequency division multiplexing (FDM technologies). Such switches are strongly influenced by external interference, which is difficult to distinguish from the desired signal. In analog telephone networks, digital automatic telephone exchanges are increasingly used, which transmit voice among themselves in digital form. Only the subscriber termination remains analog in such networks. The more digital automatic telephone exchanges in the telephone network, the higher the quality of the channel.

All-digital switch telephone networks and ISDN networks provide users with high-quality communication lines, and ISDN connection set-up times are significantly reduced.

When connecting mass subscribers to the corporate network, for example, enterprise employees working from home, the telephone network turns out to be the only suitable type of global service for reasons of availability and cost (with a short time of communication between a remote employee and the corporate network).

2.3. Packet-switched wide area networks

To reliably integrate local networks and large PCs into a corporate network, the technology of global packet-switched networks was used. Also, TCP / IP territorial networks were used to connect local networks.

SMDS (Switched Multi-megabit Data Service) technology was developed to interconnect local networks on a metropolitan scale, as well as provide high-speed access to global networks.

This table lists the characteristics of the main types of networks.

2.4. Backbone and access networks

• backbone networks;
• access networks.

Backbone territorial networksare used to form peer-to-peer connections between large local area networks belonging to large divisions of the enterprise. Backbone wide area networks must provide high throughput, since the backbone combines the flows of a large number of subnets. In addition, they must be constantly available, i.e. provide very high availability, as they carry the traffic of many applications critical to the success of the enterprise.

As backbone networks are useddigital dedicated channelswith speeds from 2 - 622 Mbit / s, which carries IP, IPX or IBM SNA architecture protocols, packet-switched networks frame relay, ATM, X.25, or TCP / IP.

With dedicated links, a mixed redundant link topology is used to ensure high availability of the backbone.

Under access networks understands the territorial networks necessary for the connection of small local area networks and individual remote computers with the central local area network of the enterprise. Quick access to corporate information from any geographic point determines the quality of decision-making by its employees for many types of enterprise activities.

ATMs or cash registers can also act as separate remote nodes, requiring access to a central database in order to obtain information about legal customers of the bank, whose plastic cards must be authorized on the spot. ATMs or cash registers are usually designed to communicate with a central computer over a network X.25 , which was developed as a network for remote access of non-intelligent terminal equipment to a central computer.

As access networks usually appliedanalogue telephone networks, ISDN networks, and less often - frame relay networks.

Software and hardware that connect computers or local area networks of remote users to the corporate network are calledby means of remote access... On the client side, these tools are represented by a modem and associated software.

The organization of mass remote access from the central local network is provided byremote access server.

Remote access serveris a hardware and software complex that combines the functions of a router, bridge and gateway. The server performs one or another function depending on the type of protocol used by the remote user or remote network. Remote access servers usually have enough low speed ports to connect users over analogue telephone networks or ISDN.

PAGE 2

Purpose and structure of global networks

A global computer network, GKS (English Wide Area Network, WAN) is a computer network that covers large areas and includes a large number of computers.

Global networks allow you to organize interaction between subscribers thousands of kilometers away. Data transmission in wide area networks is based on packet switching technology.

Each transmitted file is split into small chunks, which are placed in a packet containing the addresses of both the sending and receiving computers.

Packets travel the network on their own: if one packet is lost, it can be easily re-sent. Since each packet is sent independently of the others and is mixed with thousands of similar ones, this, among other things, provides a relatively cheap data transfer over the Internet. For example, the cost of sending an email is negligible compared to the cost of faxing a message of equal size.

Global networks are also called territorial computer networks, serve in order to provide their services to a large number of end subscribers scattered over a large territory - within a region, region, country, continent or the entire globe.

Due to the large length of communication channels, the construction of a global network requires very large costs, which include the cost of cables and work on their laying, the cost of switching equipment and intermediate amplifying equipment that provides the necessary channel bandwidth, as well as operating costs for the constant maintenance of the network equipment scattered over a large area in a working condition.

Typical subscribers to global computer network are local networks of enterprises located in different cities and countries that need to exchange data with each other. Individual computers also use the services of global networks. Large mainframe computers typically provide access to corporate data, while personal computers are used to access corporate and public Internet data.

Global networks are usually created by large telecommunications companies to provide paid services to subscribers. Such networks are called public or public... There are also concepts such as network operator and network service provider.

Network operator(network operator) is the company that maintains the normal operation of the network. Service provider often referred to as provider(service provider) is a company that provides paid services to network subscribers. The owner, operator and service provider can be combined into one company, or they can be from different companies.

Much less often, the global network is completely created by some large corporation(such as Dow Jones or Transneft) for their internal needs. In this case, the network is called private. Very common and intermediate option- the corporate network uses the services or equipment of the public global network, but supplements these services or equipment with its own. The most typical example here is the lease of communication channels, on the basis of which own territorial networks are created.

In addition to computing global networks, there are also other types territorial networks of information transmission. First of all, these are telephone and telegraph networks, which have been operating for many decades, as well as a telex network.

Due to the high cost of global networks, there is a long-term trend towards creating a single global network that can transmit data of any type: computer data, telephone conversations, faxes, telegrams, television images, teletex (data transmission between two terminals), videotex (receiving data stored in the network to your terminal), etc., etc.

Although local and global computer networks are based on the same method - the method packet switching, wide area networks have a lot of differences from local networks ..

Organization of complex connections in global networks. In wide area networks, communication between LANs is carried out through bridges.

Bridges are software and hardware complexes that connect LANs to each other, as well as LANs and remote PC workstations, allowing them to interact with each other to expand the ability to collect and exchange information.

A bridge is generally defined as a connection between two networks that use the same communication protocol, the same media type, and the same addressing structure.

There are two basic types of NETWARE bridges: n internal n external.

If the bridge is on a file server, the internal bridge. If the bridge is located in a workstation, the external bridge. External bridges and their software are installed on a workstation that does not function as a file server. Therefore, the external bridge can transfer data more efficiently than the internal one.

There are dedicated and shared bridges.

Dedicated is a PC that is used as a bridge and cannot function as a workstation. Combined - it can function both as a bridge and as a workstation - at the same time. The benefit is limited to the cost of purchasing an additional computer. The disadvantage is the lack of potential capabilities of the workstation housed in it. When an application on the PC hangs and causes the PC to stop functioning as a bridge, the bridge program also stops operations.

This failure interrupts the sharing of data between networks, and also interrupts PC sessions that are bridged to the file server. Since the dedicated bridge is not used as a PC, no PPs will cause such a failure and will not interrupt the operation. When choosing a bridge, the cost of the equipment must be weighed against the risk of the possibility of bridge failure. A local bridge transfers data between networks that are located within the cable's distance limits. Local bridges are used in the following cases 1 to divide large networks into two or more subnets in order to increase performance and reduce the cost of communication lines. For example, in one organization, different departments share the same network. Because large networks are slower than small ones, that is, the ability to allocate compactly located departments into small subnets.

By using Netware Local Bridging, departments can continue to partition data as if they were on the same network, while gaining the speed and flexibility of a small network. 2, using a local bridge, you can expand the physical capabilities of the network. If a Netware network has the maximum allowable number of nodes supported by its hardware addressing scheme and there is a need to add several more nodes, then a Netware bridge is used to expand such a network.

In this case, the inclusion of an additional file server in the network is optional. 3 interconnection of networks. In order for users of each network to be able to access the information of other networks, it is necessary to link these networks, forming an inter-network. Remote bridging is used when the distance does not allow the networks to be connected via cable.

For example, connecting the network in Kostroma to the network in Novgorod will make it necessary to use a remote bridge, since the cable length limit for the local bridge will be exceeded. The remote bridge uses the intermediate transmission medium of telephone lines to connect to a remote network or remote PCs. When connecting a network to a remote network, a bridge must be established at each end of the connection, and when connecting a network to a remote PC, a bridge is required only on the network. The choice of modems for organizing remote interaction should be determined by the characteristics and type of communication channels, as well as the requirements for the capabilities of the modems and their cost.

Note V - up to 2400 baud - tel. communication channels 1baud 1bit sec, used with low and medium-speed asynchronous modems asynchronous V - up to 19.2 baud - in leased lines, synchronous usually a telephone line with a maximum speed V 64 Kbit s, or dial-up telephone. line with data rate V 9600 bit s. Netware Remote Bridges support two kinds of serial communication methods, asynchronous and synchronous.

The main difference between a protected - mode bridge and a real - mode bridge is the amount of memory it can support. A secure bridge allows you to add memory, while a real bridge provides a minimum of memory. Bridge in protected mode.

Bridge software in protected mode supports standard 1MB of bridge memory 640KB RAM add. memory The software also supports the installation of memory cards up to a total of 8 MB. This amount of extra memory allows you to have a bridge on which additional. Valua Added Processes - VAPs up to 7 MB in memory. If you plan to install more than one or two VAPs, you should choose a secure mode bridge.

In this case, it is necessary to determine additional. number of memory cards. The number of cards you add depends on how many VAPs you plan to run. If more than two VAPs will be running, at least one card must be installed. Note. If you need to perform 4 VAP processes, such as VAP printing and VAP queuing, the bridge must work in a protected mode. Before using a bridge in secure mode, you must ensure that the type of computer is compatible with the combined mode.

Bridge in real mode. The real-mode bridge software supports the standard 640KB of main memory, in which case one or two additional oriented VAPs can run on the bridge. Bridges in real mode can be either dedicated or combined. The computing network allows network users to use the network printing service in their work. Network printing devices PU can be printers, plotters or any peripheral devices.

The CP is networked if it is connected from the outside to a PC workstation or network, and can be used for the benefit of various users or groups of network users from different parts of the network. The latest models of modern PUs have great functionality and high performance. They are quite expensive and their application in the form of local ones will be associated with large material costs. NETWARE print service allows multiple users to use it more efficiently.

For example, one XEROX laser printer connected to the network will make it possible to save money without purchasing others. When a non-network station sends a print request to a printer attached to it, the request is immediately sent for execution. If the user will work with network printers, then the information that he displays from the CP will be sent first to the file or print server, and only then to the printer.

When the printer is ready to execute the next request, the print server selects the print job from the queue and sends it to the printer corresponding to this queue. The print server is a part of the file server software component that selects print jobs from the queue and sends them to the printer. The print server can also be present on the network in the form of a specialized workstation that is designed to serve the printing process on the network, or it can be combined with the bridge software.

In a network, the process of network printing can also be carried out on printers connected to conventional remote PCs. The NETWARE print server increases the printing capabilities of the network, it can serve up to 16 printers connected to various computers connected to the network and can be installed installation - installation of a software product on a PC on a file server, bridge or specialized PC. The print server software is usually co-located with the file server software and uses VAP processes loaded on the file server.

VAP processes of the print server use up to 128 K of memory in the process of working on a file server or bridge, including DOS when loading on a bridge. For each printer, another 10 K is added. When using a specialized print server on a PC, it requires 200 K of memory for its operation, plus 10 K for each connected printer. These numbers may vary depending on the workload of the print server. The remote printer requires 9K memory on its PC. This figure also includes the amount of buffer required to operate the printer. The remote printer will function when the file server is off, if the print server is designed as a specialized PC or is installed on a bridge.

In the NETWARE system, the printing process is implemented as follows: the PC shell sends a file over the network to a file or print server, where, according to system planning, it is buffered and queued with job parameters for printing. When users send information to print at the same time, the request received first will be processed first.

All subsequent requests are queued and processed in that order, unless they receive the highest priority. The work order for printing is the characteristics that determine how the printing should be done. These include the mode, size, number of copies, and specifying the specific printer that will do the job. Each user creates a print job and sends it to a file or print server, where it is already queued.

NETWARE version 2.15 allows one printer to serve multiple queues, and one queue can be served by multiple printers. For example, if there are multiple print requests, Printer0 and Printer1 may be given a higher priority queue job. You can also define which users are allowed to place print jobs in each queue. Any print queue must be scheduled using special tools.

You can establish a mapping between print queues and printers using commands that are entered from the file server console or from a prepared autoexec.sys file. 4.3.

End of work -

This topic belongs to the section:

Information technology in the economy. Basics of Networked Information Technology

LANs are being intensively implemented in medicine, agriculture, education, science, etc. Local area network - LAN - Local Area Network, this name .. Currently, information and computing systems are usually divided into 3 .. TOP Technical and Office Protocol - a protocol for the automation of technical and an administrative institution. MAR TOP ..

If you need additional material on this topic, or you did not find what you were looking for, we recommend using the search in our database of works:

What will we do with the received material:

If this material turned out to be useful for you, you can save it to your page on social networks: