Corporate information system (CIS) is a set of information systems of individual divisions of an enterprise, united by a common document flow, such that each of the systems performs part of the tasks of managing decision-making, and all systems together ensure the functioning of the enterprise in accordance with ISO 9000 quality standards.

Historically, there have been a number of requirements for corporate information systems. These requirements are:

Systematicity;

Complexity;

Modularity;

Openness;

Adaptability;

Reliability;

Safety;

Scalability;

Mobility;

Easy to learn;

Support for implementation and maintenance from the developer.

Let's look at these requirements in more detail.

In modern conditions, production cannot exist and develop without a highly effective management system based on the most modern information technologies. Constantly changing market requirements, huge flows of information of a scientific, technical, technological and marketing nature require the enterprise personnel responsible for the strategy and tactics of development of a high-tech enterprise to quickly and accurately make decisions aimed at obtaining maximum profits at minimum costs. Optimizing costs and increasing the reactivity of production in accordance with the ever-increasing demands of consumers in conditions of fierce market competition cannot be based only on speculative conclusions and intuition of even the most experienced employees. What is needed is comprehensive control over all cost centers in an enterprise, complex mathematical methods of analysis, forecasting and planning, based on taking into account a huge number of parameters and criteria and a coherent system for collecting, accumulating and processing information. Extensive ways to solve this problem, associated with the exorbitant growth of the administrative apparatus, even with the best organization of its work, cannot give a positive result. The transition to modern technologies and the reorganization of production cannot bypass such a key aspect as management. And there can only be one way here - the creation of a CIS that meets a number of stringent requirements.

CIS, first of all, must meet the requirements of complexity and consistency. It should cover all levels of management from the corporation as a whole, taking into account branches, subsidiaries, service centers and representative offices, to the workshop, site and specific workplace and employee. From the point of view of computer science, the entire production process is a continuous process of generating, processing, changing, storing and distributing information. Each workplace - be it an assembler on an assembly line, an accountant, a manager, a storekeeper, a marketing specialist or a technologist - is a node that consumes and generates certain information. All such nodes are interconnected by information flows embodied in the form of documents, messages, orders, actions, etc. Thus, a functioning enterprise can be represented in the form of an information-logical model consisting of nodes and connections between them. Such a model should cover all aspects of the enterprise’s activities, should be logically justified and aimed at identifying mechanisms for achieving the main goal in market conditions - maximum profit, which implies the requirement of consistency. A fairly effective solution to this problem is possible only on the basis of strict consideration of the maximum possible reasonable set of parameters and the possibility of multi-criteria multivariate analysis, optimization and forecasting - that is, the complexity of the system.

Information in such a model is distributed in nature and can be quite strictly structured at each node and in each thread. Nodes and flows can be conditionally grouped into subsystems, which puts forward another important requirement for a CIS - modularity of construction. This requirement is also very important from the point of view of system implementation, since it allows us to parallelize, facilitate and, accordingly, speed up the process of installation, personnel training and launching the system into commercial operation. In addition, if the system is not created for a specific production, but is purchased on the market of ready-made systems, modularity makes it possible to exclude from the supply components that do not fit into the information model of a particular enterprise or which can be dispensed with at the initial stage, which saves money.

Since no real system, even if it is created on a special order, can be exhaustively complete (the immensity cannot be grasped) and during operation there may be a need for additions, and also due to the fact that in a functioning enterprise there may be already working and proven the usefulness of CIS components, the next defining requirement is openness. This requirement takes on particular importance if we consider that automation is not limited to control, but also covers such tasks as design and maintenance, technological processes, internal and external document flow, communication with external information systems (for example, the Internet), security systems, etc.

Any enterprise does not exist in a closed space, but in a world of constantly changing supply and demand, requiring a flexible response to the market situation, which can sometimes be associated with a significant change in the structure of the enterprise and the range of products or services provided. In addition, in a transition economy, legislation is unstable and dynamically changing. Large corporations may also have extraterritorial divisions located in the jurisdiction of other countries or free economic zones. This means that the CIS must have the property of adaptability, that is, be flexible in adjusting to different legislation, have multi-lingual interfaces, and be able to work with different currencies at the same time. A system that does not have the property of adaptability is doomed to a very short existence, during which it is unlikely to be able to recoup the costs of its implementation. It is desirable that, in addition to configuration tools, the system also has development tools - tools with which programmers and the most qualified users of the enterprise could independently create the components they need, which would be organically integrated into the system.

When the CIS is operated in industrial mode, it becomes an indispensable component of a functioning enterprise, capable of stalling the entire production process and causing enormous losses in the event of an emergency shutdown. Therefore, one of the most important requirements for such a system is the reliability of its functioning, implying the continuity of the functioning of the system as a whole, even in conditions of partial failure of its individual elements due to unforeseen and insurmountable reasons.

Extremely great importance for any large-scale system containing a large amount of information has security. The security requirement includes several aspects:

Protecting data from loss. This requirement is implemented mainly at the organizational, hardware and system levels. An application system, such as an automated control system, does not necessarily have to contain tools Reserve copy and data recovery. These issues are addressed at the operating environment level.

Maintaining data integrity and consistency. The application system must track changes to interdependent documents and provide versioning and generational control of data sets.

Preventing unauthorized access to data within the system. These tasks are solved comprehensively both by organizational measures and at the level of operating and application systems. In particular, application components must have developed administration tools that allow restricting access to data and functionality system depending on the user’s status, as well as monitor user actions in the system.

Preventing unauthorized access to data from outside. The solution to this part of the problem falls mainly on the hardware and operating environment of the CIS and requires a number of administrative and organizational measures.

An enterprise that operates successfully and earns sufficient profit tends to grow and form subsidiaries and branches, which during the operation of the CIS may require an increase in the number of automated workstations and an increase in the volume of stored and processed information. In addition, for companies such as holding companies and large corporations, it should be possible to use the same management technology both at the level of the parent enterprise and at the level of any, even small, member company. This approach puts forward the requirement of scalability.

At a certain stage of enterprise development, increasing requirements for system performance and resources may require a transition to a more productive hardware and software platform. To ensure that such a transition does not entail a radical disruption of the management process and unjustified capital investments in the acquisition of more powerful application components, it is necessary to fulfill the mobility requirement.

Ease of learning is a requirement that includes not only the presence of an intuitive program interface, but also the availability of detailed and well-structured documentation, the possibility of training personnel in specialized courses and internships for responsible specialists at related enterprises where this system is already in use.

Developer support. This concept includes a number of possibilities, such as obtaining new versions software free of charge or with a significant discount, obtaining additional methodological literature, consultations on hotline, obtaining information about other software products of the developer, the opportunity to participate in seminars, scientific and practical user conferences and other events held by the developer or user groups, etc. Naturally, only a serious company that operates steadily in the software market and has a fairly clear outlook for the future can provide such support to the user.

Escort. During the operation of complex software and hardware systems, situations may arise that require prompt intervention by qualified personnel of the developer company or its representative on site. Support includes a specialist visiting the customer’s site to eliminate the consequences emergency situations, technical training at the customer’s site, methodological and practical assistance if necessary to make changes to the system that are not in the nature of radical restructuring or new development. This also includes the installation of new releases of software received from the developer free of charge by a supporting organization authorized by the developer or by the developer himself.

Summary: The CIS must meet the requirements:

Complexity and consistency;

Modularity;

Openness;

Reliability;

Security;

Scalability;

Mobility;

Ease of learning;

Developer support;

Support by the developer or his representative.

In turn, the application system, which is an automated control system, puts forward a number of requirements for the environment in which it operates. The operating environment of the application system is a network operating system, operating systems on workstations, a database management system and a number of auxiliary subsystems that provide security functions, archiving, etc. Typically, a list of these requirements and instructions for a specific set of system software are contained in the documentation for the specific application system.

Concept of corporate information system. Integrated Information Technologies- Union various types information technologies.

Currently, there is a tendency to combine various types of information technologies into a single computer-technological complex, which is called integrated .

A special place in it belongs to means of communication, which provide not only extremely broad technological capabilities for automating various types of activities, but also form the basis for the creation of various network options for automated information technologies (local, multi-level distributed, global computer networks, e-mail, digital networks of integrated services).

All of them are focused on the technological interaction of a set of objects formed by devices for transmitting, processing, accumulating, storing and protecting data, and are integrated computer data processing systems of great complexity with practically unlimited operational capabilities for the implementation of management processes in the economy.

Integrated Computer Technologies data processing is designed as a complex information technology and software complex. It supports a unified way of presenting data and user interaction with system components, and provides the information and computing needs of specialists that arise in the course of their professional work.

Integrated computer technologies provided the basis for the implementation of corporate information systems (CIS).

Corporate information system, or CIS for short, is the now generally accepted name and abbreviation for integrated management information systems.

Abroad, such systems are almost called Management Information System (MIS), the only thing is that the adjective “integrated”, which is important here, is missing. These systems are the successors of integrated automated control systems.

Corporate networks are an integral part of corporate information systems.

Corporate computer networks. Corporate networks- enterprise and corporation scale networks.

Since these networks usually use the communication capabilities of the Internet, geographical location does not matter for them.

Corporate networks are a special type of local network that has a significant coverage area. Nowadays, corporate networks are developing very actively and they are often called Intranet networks ( Intranet).

Intranet network (Intranet) - This is a private intra-company or inter-company computer network that has expanded capabilities due to the use of Internet technologies, has access to the Internet, but is protected from access to its resources by external users.

Intranet system can also be defined as a system for storing, transmitting, processing and accessing inter-company and intra-company information using local networks and the Internet. The Intranet is a technology for managing corporate communications, in contrast to the Internet, which is a technology for global communications.

Fully featured network Internet must ensure at a minimum the implementation of such basic network technologies as:

■ network management;

■ a network directory that reflects all other services and resources;

■ network file system;

■ integrated messaging (e-mail, fax, teleconferencing, etc.);

■ work on the World Wide Web;

■ network printing;

■ protection of information from unauthorized access.

The Intranet network can be isolated from external Internet users using network protection tools - firewalls. Firewall software, usually located on web servers or proxy servers, at a minimum checks the authority of the external subscriber and his knowledge of the password, thereby providing protection against unauthorized access to the network and obtaining confidential information from it. Information on the Internet and all its services are available to all users of the corporate network.

In today's highly competitive market, gaining access to the latest information is becoming a critical component of business success. Therefore, the Intranet can now be considered as the most promising environment for implementing corporate applications.

The process of developing enterprise systems is significantly simplified, since there is no need to develop an integration project. Thus, individual departments can create their own subsystems using their own LANs and servers, without connecting them in any way with other departments. If necessary, they can be connected to unified system enterprises.

The client computer must have a program - browser, which provides access to WWW objects and translates HTML files into a visible image. These files must be accessible regardless of the user's operating environment.

Thus, server applications should be designed to be client-invariant and their development should be entirely focused on implementation functional tasks corporations and availability universal client.

Modern management systems for large enterprises have gone from strictly centralized to distributed systems. Information technology that provides support for distributed control was built on systems with a client-server architecture.

Distributed management was combined with distributed communications, although serious problems arose in the field of managing distributed databases (ensuring the integrity and consistency of data, synchronous updating, protection from unauthorized access), administering information and computing resources of the network, etc.

Building management systems based on Intranet principles allows you to combine the best qualities of centralized information storage systems with distributed communications.

The Intranet architecture was a natural development of information systems: from systems with a centralized architecture, through client-server systems to the Intranet.

The entire information system is located on a central computer. At workplaces there are simple access devices (navigators) that provide the ability to manage processes in the information system. All processes are carried out on a central computer, with which the access device communicates via a simple protocol, by transmitting screens and codes of keys pressed on the remote control. The main advantages of Intranet systems:

■ the server produces information (not data) in a form convenient for presentation to the user;

■ an open protocol is used to exchange information between the client and the server;

■ the application system is concentrated on the server; only the navigator program is located on the clients;

■ centralized management of the server part and workstations is facilitated;

■ a unified interface that is independent of the software used by the user (operating system, DBMS, etc.).

An important advantage of the Intranet is the openness of the technology. Existing software based on proprietary technologies, when solutions are developed by one company for one application, may seem more functional and convenient, but they sharply limit the possibilities for the development of information systems. Currently, the Intranet system widely uses open standards in the following areas:

■ network resource management (SMTP, IMAP, MIME);

■ teleconferences (NNTP);

■ information service (NTRR, HTML);

■ help desk(LDAP);

■ programming (Java).

Trends in further development of the Intranet:

■ intelligent network search;

■ high interactivity of navigators through the use of Java technology;

■ network computers;

■ turning the navigator interface into a universal interface with a computer.

The intranet provides a tangible economic effect in the activities of the organization, which is primarily associated with a sharp improvement in the quality of information consumption and its direct impact on the production process. For an organization’s information system, the key concepts are “information publication”, “information consumers”, “information presentation”.

Conclusions:

1. Distributed data processing means that the user and his application programs (applications) get the opportunity to work with tools located in distributed nodes of the network system.

2. The implementation of client-server technologies may have differences in the efficiency and cost of information and computing processes, as well as in the levels of software and hardware, in the mechanism of component connections, in the speed of access to information, its diversity, etc.

3. There is a trend towards further globalization of the global process of informatization of society. The technological basis is the global information superhighway and the national information infrastructures of advanced countries, united on the basis of international standards and protocols of information interaction into a qualitatively new information education - the global information infrastructure (Global Information Infrastructure - GIL).

4. Electronic document management represents a system for manipulating official electronic documents in a standardized form and based on the regulations adopted in the system.

5. Basic procedures for managing electronic documents are combined into groups of procedures for creating documents, storing them and manipulating documents.

6. Currently, there is a tendency to combine various types of information technologies into a single computer-technological complex, called integrated.

7. Corporate information system, or CIS for short, is the now generally accepted name and abbreviation for integrated management information systems.

8. The Intranet system (Intranet) is a private intra-company or inter-company computer network that has expanded capabilities due to the use of Internet technologies, has access to the Internet, but is protected from access to its resources by external users.

9. The Intranet system provides a tangible economic effect in the organization’s activities, which is primarily associated with a sharp improvement in the quality of information consumption and its direct impact on the production process. For an organization’s information system, the key concepts are “information publication”, “information consumers”, “information presentation”.

Introduction. From the history of network technologies. 3

The concept of "Corporate networks". Their main functions. 7

Technologies used in creating corporate networks. 14

Structure of the corporate network. Hardware. 17

Methodology for creating a corporate network. 24

Conclusion. 33

List of used literature. 34

Introduction.

From the history of network technologies.

The history and terminology of corporate networks is closely related to the history of the origins of the Internet and the World Wide Web. Therefore, it does not hurt to remember how the very first network technologies appeared, which led to the creation of modern corporate (departmental), territorial and global networks.

The Internet began in the 60s as a project of the US Department of Defense. The increased role of the computer has given rise to the need for both sharing information between different buildings and local networks, and maintaining the overall functionality of the system in the event of failure of individual components. The Internet is based on a set of protocols that allow distributed networks to route and transmit information to each other independently; if one network node is unavailable for some reason, the information reaches its final destination through other nodes, which this moment in working order. The protocol developed for this purpose is called Internetworking Protocol (IP). (The acronym TCP/IP means the same thing.)

Since then, the IP protocol has become generally accepted in military departments as a way to make information publicly available. Since many of these departments' projects were carried out in various research groups at universities around the country, and the method of exchanging information between heterogeneous networks proved to be very effective, the use of this protocol quickly expanded beyond the military departments. It began to be used in NATO research institutes and European universities. Today, the IP protocol, and therefore the Internet, is a universal global standard.

In the late eighties, the Internet faced a new problem. At first, the information was either emails or simple data files. Appropriate protocols have been developed for their transfer. Now, a whole series of new types of files have emerged, usually united under the name multimedia, containing both images and sounds, and hyperlinks, allowing users to navigate both within one document and between different documents containing related information.

In 1989, the Laboratory of Elementary Particle Physics of the European Center for Nuclear Research (CERN) successfully launched a new project, the goal of which was to create a standard for transmitting this kind of information over the Internet. The main components of this standard were multimedia file formats, hypertext files, as well as a protocol for receiving such files over the network. The file format was named HyperText Markup Language (HTML). It was a simplified version of the more general Standard General Markup Language (SGML). The request servicing protocol is called HyperText Transfer Protocol (HTTP). In general, it looks like this: a server running a program that serves the HTTP protocol (HTTP demon) sends HTML files upon request from Internet clients. These two standards formed the basis for a fundamentally new type of access to computer information . Standard multimedia files can now not only be obtained upon user request, but also exist and be displayed as part of another document. Since the file contains hyperlinks to other documents that may be located on other computers, the user can access this information with a light click of the mouse button. This fundamentally removes the complexity of accessing information in a distributed system. Multimedia files in this technology are traditionally called pages. A page is also the information that is sent to the client machine in response to each request. The reason for this is that a document usually consists of many separate parts, interconnected by hyperlinks. This division allows the user to decide for himself which parts he wants to see in front of him, saves his time and reduces network traffic. The software product that the user directly uses is usually called a browser (from the word browse - to graze) or a navigator. Most of them allow you to automatically retrieve and display a specific page that contains links to documents that the user accesses most often. This page is called the home page, and there is usually a separate button to access it. Each non-trivial document is usually provided with a special page, similar to the “Contents” section in a book. This is usually where you start studying a document, so it is also often called the home page. Therefore, in general, a home page is understood as some kind of index, an entry point to information of a certain type. Usually the name itself includes a definition of this section, for example, Microsoft Home Page. On the other hand, each document can be accessed from many other documents. The entire space of documents linking to each other on the Internet is called the World Wide Web (the acronyms WWW or W3). The document system is completely distributed, and the author does not even have the opportunity to trace all the links to his document that exist on the Internet. The server providing access to these pages may log all those who read such a document, but not those who link to it. The situation is the opposite of what exists in the world of printed products. In many research fields, there are periodically published indexes of articles on a topic, but it is impossible to track all those who read a given document. Here we know those who read (had access to) the document, but we do not know who referred to it. Another interesting feature is that with this technology it becomes impossible to keep track of all the information available through the WWW. Information appears and disappears continuously, in the absence of any central control. However, this is not something to be afraid of; the same thing happens in the world of printed products. We do not try to accumulate old newspapers if we have fresh ones every day, and the effort is negligible.

Client software products that receive and display HTML files are called browsers. The first graphical browser was called Mosaic, and it was made at the University of Illinois. Many of the modern browsers are based on this product. However, due to the standardization of protocols and formats, any compatible software product can be used. Viewing systems exist on most major client systems capable of supporting smart windows. These include MS/Windows, Macintosh, X-Window and OS/2 systems. There are also viewing systems for those operating systems where windows are not used - they display text fragments of documents that are accessed.

The presence of viewing systems on such disparate platforms is of great importance. The operating environments on the author's machine, server, and client are independent of each other. Any client can access and view documents created with using HTML and corresponding standards, and transmitted through an HTTP server, regardless of the operating environment in which they were created or where they came from. HTML also supports form development and functions feedback. This means that the user interface for both querying and retrieving data goes beyond point-and-click.

Many stations, including Amdahl, have written interfaces to interoperate between HTML forms and legacy applications, creating a universal front-end user interface for the latter. This makes it possible to write client-server applications without thinking about client level coding. In fact, programs are already emerging that treat the client as a viewing system. An example is Oracle's WOW interface, which replaces Oracle Forms and Oracle Reports. Although this technology is still very young, it already has the potential to change the landscape of information management in the same way that the use of semiconductors and microprocessors changed the world of computers. It allows you to turn functions into separate modules and simplify applications, taking us to new level integration, which is more consistent with the business functions of the enterprise.

Information overload is the curse of our time. Technologies that were created to alleviate this problem have only made it worse. This is not surprising: it is worth looking at the contents of the trash bins (regular or electronic) of an ordinary employee dealing with information. Even if you don't count the inevitable heaps of advertising "junk" in the mail, most of the information is sent to such an employee simply "in case" he needs it. Add to this “untimely” information that will most likely be needed later, and here you have the main contents of the trash can. An employee will likely store half of the information that "might be needed" and all of the information that will likely be needed in the future. When the need arises, he will have to deal with a bulky, poorly structured archive of personal information, and at this stage additional difficulties may arise due to the fact that it is stored in files of different formats on different media. The advent of photocopiers made the situation with information “that might suddenly be needed” even worse. The number of copies, instead of decreasing, is only increasing. Email only made the problem worse. Today, a “publisher” of information can create his own, personal mailing list and, using one command, send an almost unlimited number of copies “in case” they may be needed. Some of these information distributors realize that their lists are no good, but instead of correcting them, they put a note at the beginning of the message that reads something like: "If you are not interested..., destroy this message." The letter will still clog up the mailbox, and the recipient will in any case have to spend time reading it and destroying it. The exact opposite of "maybe useful" information is "timely" information, or information for which there is a demand. Computers and networks were expected to help in working with this type of information, but so far they have not been able to cope with this. Previously, there were two main methods of delivering timely information.

When using the first of them, information was distributed between applications and systems. To gain access to it, the user had to study and then constantly carry out many complex access procedures. Once access was granted, each application required its own interface. Faced with such difficulties, users usually simply refused to receive timely information. They were able to master access to one or two applications, but they were no longer sufficient for the rest.

To solve this problem, some enterprises have attempted to accumulate all distributed information on one main system. As a result, the user received a single access method and a single interface. However, since in this case all enterprise requests were processed centrally, these systems grew and became more complex. More than ten years have passed, and many of them are still not filled with information due to the high cost of entering and maintaining it. There were other problems here too. The complexity of such unified systems made them difficult to modify and use. To support discrete transaction process data, tools were developed to manage such systems. Over the past decade, the data we deal with has become much more complex, making the information support process more difficult. The changing nature of information needs, and how difficult it is to change in this area, has given rise to these large, centrally managed systems that are holding back requests at the enterprise level.

Web technology offers a new approach to on-demand information delivery. Since it supports the authorization, publication and management of distributed information, new technology does not lead to the same complexities as older centralized systems. Documents are created, maintained, and published directly by the authors, without having to ask programmers to create new data entry forms and reporting programs. With new browsing systems, the user can access and view information from distributed sources and systems using a simple, unified interface without having any idea about the servers they are actually accessing. These simple technological changes will revolutionize information infrastructures and fundamentally change how our organizations operate.

The main distinguishing feature of this technology is that control of the flow of information is in the hands not of its creator, but of the consumer. If the user can easily retrieve and review information as needed, it no longer has to be sent to them "just in case" it is needed. The publishing process can now be independent of automatic information dissemination. This includes forms, reports, standards, meeting scheduling, sales enablement tools, training materials, schedules, and a host of other documents that tend to fill our trash bins. For the system to work, as stated above, we need not only a new information infrastructure, but also a new approach, a new culture. As creators of information, we must learn to publish it without disseminating it, and as users, we must learn to be more responsible in identifying and monitoring our information needs, actively and efficiently obtaining information when we need it.

The concept of "Corporate networks". Their main functions.

Before we talk about private (corporate) networks, we need to define what these words mean. IN Lately this phrase has become so widespread and fashionable that it has begun to lose its meaning. In our understanding, a corporate network is a system that ensures the transfer of information between various applications used in the corporate system. Based on this completely abstract definition, we will consider various approaches to creating such systems and try to fill the concept of a corporate network with concrete content. At the same time, we believe that the network should be as universal as possible, that is, allow the integration of existing and future applications with the lowest possible costs and restrictions.

A corporate network, as a rule, is geographically distributed, i.e. uniting offices, divisions and other structures located at a considerable distance from each other. Often corporate network nodes are located in different cities and sometimes countries. The principles by which such a network is built are quite different from those used when creating a local network, even covering several buildings. The main difference is that geographically distributed networks use fairly slow (today tens and hundreds of kilobits per second, sometimes up to 2 Mbit/s) leased communication lines. If when creating a local network the main costs are for the purchase of equipment and cable laying, then in geographically distributed networks the most significant element of cost is the rental fee for the use of channels, which grows rapidly with increasing quality and speed data transmission. This limitation is fundamental, and when designing a corporate network, all measures should be taken to minimize the volume of transmitted data. Otherwise, the corporate network should not impose restrictions on which applications and how they process information transferred over it.

By applications we mean here system software - databases, postal systems, computing resources, file service, etc. - as well as the tools with which the end user works. The main tasks of a corporate network are the interaction of system applications located in various nodes and access to them by remote users.

The first problem that has to be solved when creating a corporate network is the organization of communication channels. If within one city you can count on renting dedicated lines, including high-speed ones, then when moving to geographically distant nodes, the cost of renting channels becomes simply astronomical, and their quality and reliability often turn out to be very low. A natural solution to this problem is to use already existing wide area networks. In this case, it is enough to provide channels from offices to the nearest network nodes. The global network will take on the task of delivering information between nodes. Even when creating a small network within one city, you should keep in mind the possibility of further expansion and use technologies that are compatible with existing global networks.

Often the first, or even the only, such network that comes to mind is the Internet. Using the Internet in corporate networks Depending on the tasks being solved, the Internet can be considered at different levels. For the end user, this is primarily a worldwide system for providing information and postal services. The combination of new technologies for accessing information, united by the concept of the World Wide Web, with a cheap and publicly accessible global computer communications system, the Internet, has actually given birth to a new mass media, which is often simply called the Net. Anyone who connects to this system perceives it simply as a mechanism that gives access to certain services. The implementation of this mechanism turns out to be absolutely insignificant.

When using the Internet as the basis for a corporate data network, it turns out that interesting thing. It turns out that the Network is not a network at all. This is exactly the Internet - interconnection. If we look inside the Internet, we see that information flows through many completely independent and mostly non-commercial nodes, connected through a wide variety of channels and data networks. The rapid growth of services provided on the Internet leads to overload of nodes and communication channels, which sharply reduces the speed and reliability of information transfer. At the same time, Internet service providers do not bear any responsibility for the functioning of the network as a whole, and communication channels are developing extremely unevenly and mainly where the state considers it necessary to invest in it. Accordingly, there are no guarantees about the quality of the network, the speed of data transfer, or even simply the reachability of your computers. For tasks in which reliability and guaranteed time of information delivery are critical, the Internet is far from The best decision. In addition, the Internet binds users to one protocol - IP. This is good when we use standard applications that work with this protocol. Using any other systems with the Internet turns out to be difficult and expensive. If you need to provide mobile users with access to your private network, the Internet is also not the best solution.

It would seem that there shouldn’t be any big problems here - there are Internet service providers almost everywhere, take a laptop with a modem, call and work. However, the supplier, say, in Novosibirsk, has no obligations to you if you connect to the Internet in Moscow. He does not receive money for services from you and, of course, will not provide access to the network. Either you need to conclude an appropriate contract with him, which is hardly reasonable if you find yourself on a two-day business trip, or call from Novosibirsk to Moscow.

Another Internet problem that has been widely discussed lately is security. If we are talking about a private network, it seems quite natural to protect transmitted information from someone else's gaze. The unpredictability of information paths between many independent Internet nodes not only increases the risk that some overly curious network operator can put your data on their disk (technically this is not so difficult), but also makes it impossible to determine the location of the information leak. Encryption tools solve the problem only partially, since they are applicable mainly to mail, file transfer, etc. Solutions that allow you to encrypt information in real time at an acceptable speed (for example, when working directly with a remote database or file server) are inaccessible and expensive. Another aspect of the security problem is again related to the decentralization of the Internet - there is no one who can restrict access to the resources of your private network. Since this is an open system where everyone sees everyone, anyone can try to get into your office network and gain access to data or programs. There are, of course, means of protection (the name Firewall is accepted for them - in Russian, or more precisely in German, “firewall” - fire wall). However, they should not be considered a panacea - remember about viruses and antivirus programs. Any protection can be broken, as long as it pays off the cost of hacking. It should also be noted that you can make a system connected to the Internet inoperable without invading your network. There are known cases of unauthorized access to the management of network nodes, or simply using the features of the Internet architecture to disrupt access to a particular server. Thus, the Internet cannot be recommended as a basis for systems that require reliability and closedness. Connecting to the Internet within a corporate network makes sense if you need access to the enormous information space, which is actually called the Network.

A corporate network is a complex system that includes thousands of diverse components: computers different types, from desktop to mainframes, system and application software, network adapters, hubs, switches and routers, cable system. The main task of system integrators and administrators is to ensure that this cumbersome and very expensive system copes as best as possible with processing the flow of information circulating between employees of the enterprise and allows them to make timely and rational decisions that ensure the survival of the enterprise in fierce competition. And since life does not stand still, the content of corporate information, the intensity of its flows and the methods of processing it are constantly changing. The latest example of a dramatic change in the technology of automated processing of corporate information is in plain sight - it is associated with the unprecedented growth in the popularity of the Internet in the last 2 - 3 years. The changes brought about by the Internet are multifaceted. The WWW hypertext service has changed the way information is presented to people by collecting on its pages all the popular types of information - text, graphics and sound. Internet transport - inexpensive and accessible to almost all enterprises (and, through telephone networks, to individual users) - has significantly simplified the task of building a territorial corporate network, while simultaneously highlighting the task of protecting corporate data while transmitting it through a highly accessible public network with a multimillion-dollar population. ".

Technologies used in corporate networks.

Before setting out the basics of the methodology for building corporate networks, it is necessary to provide a comparative analysis of technologies that can be used in corporate networks.

Modern data transmission technologies can be classified according to data transmission methods. In general, there are three main methods of data transfer:

circuit switching;

message switching;

packet switching.

All other methods of interaction are, as it were, their evolutionary development. For example, if you imagine data transmission technologies as a tree, then the packet switching branch will be divided into frame switching and cell switching. Recall that packet switching technology was developed more than 30 years ago to reduce overhead and improve performance. existing systems data transmission. The first packet switching technologies, X.25 and IP, were designed to handle poor quality links. With improved quality, it became possible to use a protocol such as HDLC for information transmission, which has found its place in Frame Relay networks. The desire to achieve greater productivity and technical flexibility was the impetus for the development of SMDS technology, the capabilities of which were then expanded by the standardization of ATM. One of the parameters by which technologies can be compared is the guarantee of information delivery. Thus, X.25 and ATM technologies guarantee reliable delivery of packets (the latter using the SSCOP protocol), while Frame Relay and SMDS operate in a mode where delivery is not guaranteed. Further, the technology can ensure that the data reaches its recipient in the order it was sent. Otherwise, order must be restored at the receiving end. Packet switched networks can focus on pre-connection establishment or simply transfer data to the network. In the first case, both permanent and switched virtual connections can be supported. Important parameters also include the presence of data flow control mechanisms, traffic management systems, mechanisms for detecting and preventing congestion, etc.

Technology comparisons can also be made based on criteria such as the efficiency of addressing schemes or routing methods. For example, the addressing used may be based on geographic location (telephone numbering plan), on use in distributed networks, or on Hardware. Thus, the IP protocol uses a logical address consisting of 32 bits, which is assigned to networks and subnets. The E.164 addressing scheme is an example of a geo-location-based scheme, and the MAC address is an example of a hardware address. X.25 technology uses the Logical Channel Number (LCN), and the switched virtual connection in this technology uses the X.121 addressing scheme. In Frame Relay technology, several virtual links can be “embedded” into one link, with a separate virtual link identified by a DLCI (Data-Link Connection Identifier). This identifier is specified in each transmitted frame. DLCI has only local significance; in other words, the sender can identify the virtual channel with one number, while the recipient can identify it with a completely different number. Dialup virtual connections in this technology rely on the E.164 numbering scheme. ATM cell headers contain unique VCI/VPI identifiers, which change as cells pass through intermediate switching systems. Dialup virtual connections in ATM technology can use the E.164 or AESA addressing scheme.

Packet routing in a network can be done statically or dynamically and can either be a standardized mechanism for a specific technology or act as a technical basis. Examples of standardized solutions include the dynamic routing protocols OSPF or RIP for IP. In relation to ATM technology, the ATM Forum has defined the protocol for routing requests to establish switched virtual connections, PNNI, distinctive feature which is recording information about the quality of service.

The ideal option for a private network would be to create communication channels only in those areas where it is necessary, and transmit any network protocols, which are required by running applications. At first glance, this is a return to leased communication lines, but there are technologies for constructing data transmission networks that make it possible to organize channels within them that appear only at the right time and in the right place. Such channels are called virtual. A system that connects remote resources using virtual channels can naturally be called a virtual network. Today, there are two main virtual network technologies - circuit-switched networks and packet-switched networks. The first include the regular telephone network, ISDN and a number of other, more exotic technologies. Packet switched networks include X.25, Frame Relay and, more recently, ATM technologies. It is too early to talk about using ATM in geographically distributed networks. Other types of virtual (in various combinations) networks are widely used in the construction of corporate information systems.

Circuit-switched networks provide the subscriber with multiple communication channels with a fixed bandwidth per connection. The well-known telephone network provides one communication channel between subscribers. If you need to increase the number of simultaneously available resources, you have to install additional phone numbers, which is very expensive. Even if we forget about the low quality of communication, the limitation on the number of channels and the long connection establishment time do not allow using telephone communications as the basis of a corporate network. For connecting individual remote users, this is quite convenient and often the only available method.

Another example virtual network circuit switched is ISDN (Integrated Services Digital Network). ISDN provides digital channels(64 kbit/sec), through which both voice and data can be transmitted. A basic ISDN (Basic Rate Interface) connection includes two such channels and an additional control channel with a speed of 16 kbit/s (this combination is referred to as 2B+D). It is possible to use a larger number of channels - up to thirty (Primary Rate Interface, 30B+D), but this leads to a corresponding increase in the cost of equipment and communication channels. In addition, the costs of renting and using the network increase proportionally. In general, the limitations on the number of simultaneously available resources imposed by ISDN lead to the fact that this type of communication is convenient to use mainly as an alternative to telephone networks. On systems with no big amount ISDN nodes can also be used as the main network protocol. You just have to keep in mind that access to ISDN in our country is still the exception rather than the rule.

An alternative to circuit-switched networks is packet-switched networks. When using packet switching, one communication channel is used in a time-sharing mode by many users - much the same as on the Internet. However, unlike networks like the Internet, where each packet is routed separately, packet switching networks require a connection to be established between end resources before information can be transmitted. After establishing a connection, the network “remembers” the route (virtual channel) along which information should be transmitted between subscribers and remembers it until it receives a signal to break the connection. For applications running on a packet switching network, virtual circuits look like regular communication lines - the only difference is that their throughput and introduced delays vary depending on the network load.

The classic packet switching technology is the X.25 protocol. Nowadays it is customary to wrinkle your nose at these words and say: “it’s expensive, slow, outdated and not fashionable.” Indeed, today there are practically no X.25 networks using speeds above 128 kbit/s. The X.25 protocol includes powerful error correction capabilities, ensuring reliable delivery of information even over poor lines and is widely used where high-quality communication channels are not available. In our country they are not available almost everywhere. Naturally, you have to pay for reliability - in this case, the speed of network equipment and relatively large - but predictable - delays in the distribution of information. At the same time, X.25 is a universal protocol that allows you to transfer almost any type of data. "Natural" for X.25 networks is the operation of applications that use the OSI protocol stack. These include systems using the X.400 (email) and FTAM (file exchange) standards, as well as several others. Tools are available to implement interaction based on OSI protocols Unix systems. Another standard feature of X.25 networks is communication through regular asynchronous COM ports. Figuratively speaking, the X.25 network extends the cable connected to the serial port, bringing its connector to remote resources. Thus, almost any application that can be accessed through a COM port can be easily integrated into an X.25 network. Examples of such applications include not only terminal access to remote host computers, such as Unix machines, but also the interaction of Unix computers with each other (cu, uucp), Lotus Notes-based systems, cc:Mail and MS e-mail Mail, etc. To combine LANs in nodes connected to the X.25 network, there are methods for packaging ("encapsulating") information packets from the local network into X.25 packets. Part of the service information is not transmitted, since it can be unambiguously restored on the recipient's side. The standard encapsulation mechanism is considered to be that described in RFC 1356. It allows various local network protocols (IP, IPX, etc.) to be transmitted simultaneously through one virtual connection. This mechanism (or the older IP-only RFC 877 implementation) is implemented in almost all modern routers. There are also methods for transferring other communication protocols over X.25, in particular SNA, used in IBM mainframe networks, as well as a number of proprietary protocols from various manufacturers. Thus, X.25 networks offer a universal transport mechanism for transferring information between virtually any application. In this case, different types of traffic are transmitted over one communication channel, without “knowing” anything about each other. With LAN aggregation over X.25, you can isolate separate parts of your corporate network from each other, even if they use the same communication lines. This makes it easier to solve security and access control problems that inevitably arise in complex information structures. In addition, in many cases there is no need to use complex routing mechanisms, shifting this task to the X.25 network. Today there are dozens of global X.25 networks in the world common use , their nodes are located in almost all major business, industrial and administrative centers. In Russia, X.25 services are offered by Sprint Network, Infotel, Rospak, Rosnet, Sovam Teleport and a number of other providers. In addition to connecting remote nodes, X.25 networks always provide access facilities for end users. In order to connect to any X.25 network resource, the user only needs to have a computer with an asynchronous serial port and a modem. At the same time, there are no problems with authorizing access in geographically remote nodes - firstly, X.25 networks are quite centralized and by concluding an agreement, for example, with the Sprint Network company or its partner, you can use the services of any of the Sprintnet nodes - and these are thousands of cities all over the world, including more than a hundred in the former USSR. Secondly, there is a protocol for interaction between different networks (X.75), which also takes into account payment issues. So, if your resource is connected to an X.25 network, you can access it both from your provider's nodes and through nodes on other networks - that is, from virtually anywhere in the world. From a security point of view, X.25 networks provide a number of very attractive opportunities. First of all, due to the very structure of the network, the cost of intercepting information in the X.25 network turns out to be high enough to already serve as good protection. The problem of unauthorized access can also be solved quite effectively using the network itself. If any - even however small - risk of information leakage turns out to be unacceptable, then, of course, it is necessary to use encryption tools, including in real time. Today, there are encryption tools created specifically for X.25 networks that allow operation at fairly high speeds - up to 64 kbit/s. Such equipment is produced by Racal, Cylink, Siemens. There are also domestic developments created under the auspices of FAPSI. The disadvantage of X.25 technology is the presence of a number of fundamental speed restrictions. The first of them is associated precisely with the developed capabilities of correction and restoration. These features cause delays in the transmission of information and require a lot of processing power and performance from X.25 equipment, as a result of which it simply cannot keep up with fast communication lines. Although there is equipment that has two-megabit ports, the speed they actually provide does not exceed 250 - 300 kbit/sec per port. On the other hand, for modern high-speed communication lines, X correction means. 25 turn out to be redundant and when using them, the equipment’s power often runs idle. The second feature that makes X.25 networks considered slow is the encapsulation features of LAN protocols (primarily IP and IPX). All other things being equal, LAN communications over X.25 are, depending on network parameters, 15-40 percent slower than using HDLC over a leased line. Moreover, the worse the communication line, the higher the performance loss. We are again dealing with obvious redundancy: LAN protocols have their own correction and recovery tools (TCP, SPX), but when using X.25 networks you have to do this again, losing speed.

It is on these grounds that X.25 networks are declared slow and obsolete. But before we say that any technology is obsolete, it should be indicated for what applications and under what conditions. On low-quality communication lines, X.25 networks are quite effective and provide significant benefits in price and capabilities compared to leased lines. On the other hand, even if we count on a rapid improvement in communication quality - a necessary condition for the obsolescence of X.25 - then the investment in X.25 equipment will not be lost, since modern equipment includes the ability to migrate to Frame Relay technology.

Frame Relay networks

Frame Relay technology emerged as a means to realize the benefits of packet switching on high-speed communication lines. The main difference between Frame Relay networks and X.25 is that they eliminate error correction between network nodes. The tasks of restoring the flow of information are assigned to the terminal equipment and software of users. Naturally, this requires the use of sufficiently high-quality communication channels. It is believed that to successfully work with Frame Relay, the probability of an error in the channel should be no worse than 10-6 - 10-7, i.e. no more than one bad bit per several million. The quality provided by conventional analog lines is usually one to three orders of magnitude lower. The second difference between Frame Relay networks is that today almost all of them implement only the permanent virtual connection (PVC) mechanism. This means that when connecting to a Frame Relay port, you must determine in advance which remote resources you will have access to. The principle of packet switching - many independent virtual connections in one communication channel - remains here, but you cannot select the address of any network subscriber. All resources available to you are determined when you configure the port. Thus, on the basis of Frame Relay technology, it is convenient to build closed virtual networks used to transmit other protocols through which routing is carried out. A virtual network being "closed" means that it is completely inaccessible to other users on the same Frame Relay network. For example, in the USA, Frame Relay networks are widely used as backbones for the Internet. However, your private network can use Frame Relay virtual circuits on the same lines as Internet traffic - and be completely isolated from it. Like X.25 networks, Frame Relay provides a universal transmission medium for virtually any application. The main area of ​​application of Frame Relay today is the interconnection of remote LANs. In this case, error correction and information recovery are carried out at the level of LAN transport protocols - TCP, SPX, etc. Losses for encapsulating LAN traffic in Frame Relay do not exceed two to three percent. Methods for encapsulating LAN protocols in Frame Relay are described in the specifications RFC 1294 and RFC 1490. RFC 1490 also defines the transmission of SNA traffic over Frame Relay. The ANSI T1.617 Annex G specification describes the use of X.25 over Frame Relay networks. In this case, all the addressing, correction and recovery functions of X are used. 25 - but only between end nodes that implement Annex G. The permanent connection through the Frame Relay network in this case looks like a "straight wire" along which X.25 traffic is transmitted. X.25 parameters (packet and window size) can be selected to obtain the lowest possible propagation delays and speed loss when encapsulating LAN protocols. The absence of error correction and complex packet switching mechanisms characteristic of X.25 allows information to be transmitted over Frame Relay with minimal delays. Additionally, it is possible to enable a prioritization mechanism that allows the user to have a guaranteed minimum information transfer rate for the virtual channel. This capability allows Frame Relay to be used to transmit latency-critical information such as voice and video in real time. This relatively new feature is becoming increasingly popular and is often the main reason for choosing Frame Relay as the backbone of a corporate network. It should be remembered that today Frame Relay network services are available in our country in no more than one and a half dozen cities, while X.25 is available in approximately two hundred. There is every reason to believe that as communication channels develop, Frame Relay technology will become increasingly widespread - primarily where X.25 networks currently exist. Unfortunately, there is no single standard that describes the interaction of different Frame Relay networks, so users are locked into one service provider. If it is necessary to expand the geography, it is possible to connect at one point to the networks of different suppliers - with a corresponding increase in costs. There are also private Frame Relay networks operating within one city or using long-distance - usually satellite - dedicated channels. Building private networks based on Frame Relay allows you to reduce the number of leased lines and integrate voice and data transmission.

Structure of the corporate network. Hardware.

When building a geographically distributed network, all the technologies described above can be used. To connect remote users, the simplest and most affordable option is to use telephone communication. Where possible, ISDN networks may be used. To connect network nodes in most cases, global data networks are used. Even where it is possible to lay dedicated lines (for example, within the same city), the use of packet switching technologies makes it possible to reduce the number of necessary communication channels and, importantly, ensure compatibility of the system with existing global networks. Connecting your corporate network to the Internet is justified if you need access to relevant services. It is worth using the Internet as a data transmission medium only when other methods are unavailable and financial considerations outweigh the requirements of reliability and security. If you will use the Internet only as a source of information, it is better to use dial-on-demand technology, i.e. this method of connection, when a connection to an Internet node is established only on your initiative and for the time you need. This dramatically reduces the risk of unauthorized entry into your network from the outside. The simplest way To ensure such a connection - use dialing to the Internet node via a telephone line or, if possible, via ISDN. Another, more reliable way provide connection on demand - use a leased line and the X.25 protocol or - which is much preferable - Frame Relay. In this case, the router on your side should be configured to break the virtual connection if there is no data for a certain time and re-establish it only when data appears on your side. Widespread connection methods using PPP or HDLC do not provide this opportunity. If you want to provide your information on the Internet - for example, install a WWW or FTP server, the on-demand connection is not applicable. In this case, you should not only use access restriction using a Firewall, but also isolate the Internet server from other resources as much as possible. A good solution is to use a single Internet connection point for the entire geographically distributed network, the nodes of which are connected to each other using X.25 or Frame Relay virtual channels. In this case, access from the Internet is possible to a single node, while users in other nodes can access the Internet using an on-demand connection.

To transfer data within a corporate network, it is also worth using virtual channels of packet switching networks. The main advantages of this approach - versatility, flexibility, security - were discussed in detail above. Both X.25 and Frame Relay can be used as a virtual network when building a corporate information system. The choice between them is determined by the quality of communication channels, the availability of services at connection points and, last but not least, financial considerations. Today's costs when using Frame Relay for long distance communication are several times higher than for X.25 networks. On the other hand, higher data transfer speeds and the ability to simultaneously transmit data and voice may be decisive arguments in favor of Frame Relay. In those areas of the corporate network where leased lines are available, Frame Relay technology is more preferable. In this case, it is possible to both combine local networks and connect to the Internet, as well as use those applications that traditionally require X.25. In addition, over the same network it is possible telephone communications between nodes. For Frame Relay, it is better to use digital communication channels, but even on physical lines or voice-frequency channels you can create a quite effective network by installing the appropriate channel equipment. Good results are obtained by using Motorola 326x SDC modems, which have unique capabilities for data correction and compression in synchronous mode. Thanks to this, it is possible - at the cost of introducing small delays - to significantly increase the quality of the communication channel and achieve effective speeds of up to 80 kbit/sec and higher. On short physical lines, short-range modems can also be used, providing fairly high speeds. However, it is necessary here high quality lines, since short-range modems do not support any error correction. RAD short-range modems are widely known, as well as PairGain equipment, which allows you to achieve speeds of 2 Mbit/s on physical lines about 10 km long. To connect remote users to the corporate network, access nodes of X.25 networks, as well as their own communication nodes, can be used. In the latter case, the required amount must be allocated telephone numbers(or ISDN channels), which may be too expensive. If you need to connect a large number of users at the same time, then using X.25 network access nodes may be a cheaper option, even within the same city.

A corporate network is a rather complex structure that uses various types of communications, communication protocols and methods of connecting resources. From the point of view of ease of construction and manageability of the network, one should focus on the same type of equipment from one manufacturer. However, practice shows that there are no suppliers offering the most effective solutions for all emerging problems. A working network is always the result of a compromise - either it is a homogeneous system, suboptimal in terms of price and capabilities, or a more complex combination of products from different manufacturers to install and manage. Next, we will look at network building tools from several leading manufacturers and give some recommendations for their use.

All data transmission network equipment can be divided into two large classes -

1. peripheral, which is used to connect end nodes to the network, and

2. backbone or backbone, which implements the main functions of the network (channel switching, routing, etc.).

There is no clear boundary between these types - the same devices can be used in different capacities or combine both functions. It should be noted that backbone equipment is usually subject to increased requirements in terms of reliability, performance, number of ports and further expandability.

Peripheral equipment is a necessary component of any corporate network. The functions of backbone nodes can be taken over by a global data transmission network to which resources are connected. As a rule, backbone nodes appear as part of a corporate network only in cases where leased communication channels are used or when own access nodes are created. Peripheral equipment of corporate networks, in terms of the functions they perform, can also be divided into two classes.

Firstly, these are routers, which are used to connect homogeneous LANs (usually IP or IPX) through global data networks. In networks that use IP or IPX as the main protocol - in particular, on the Internet - routers are also used as backbone equipment that ensures the joining of various communication channels and protocols. Routers can be implemented either as stand-alone devices or as software based on computers and special communication adapters.

The second widely used type of peripheral equipment is gateways), which implement the interaction of applications running in different types of networks. Corporate networks primarily use OSI gateways, which provide LAN connectivity to X.25 resources, and SNA gateways, which provide connectivity to IBM networks. A full-featured gateway is always a hardware-software complex, since it must provide the software interfaces necessary for applications. Cisco Systems Routers Among the routers, perhaps the best known are the products of Cisco Systems, which implement a wide range of tools and protocols used in the interaction of local networks. Cisco equipment supports a variety of connection methods, including X.25, Frame Relay and ISDN, allowing you to create quite complex systems. In addition, among the Cisco router family there are excellent remote access servers for local networks, and some configurations partially implement gateway functions (what is called Protocol Translation in Cisco terms).

The main application area for Cisco routers is complex networks using IP or, less commonly, IPX as the main protocol. In particular, Cisco equipment is widely used in Internet backbones. If your corporate network is designed primarily to connect remote LANs and requires complex IP or IPX routing across heterogeneous links and data networks, then using Cisco equipment will most likely optimal choice. Tools for working with Frame Relay and X.25 are implemented in Cisco routers only to the extent that is needed to combine local networks and access them. If you want to build your system based on packet-switched networks, then Cisco routers can work in it only as purely peripheral equipment, and many of the routing functions are redundant and, accordingly, the price is too high. The most interesting for use in corporate networks are the Cisco 2509, Cisco 2511 access servers and the new Cisco 2520 series devices. Their main area of ​​application is access for remote users to local networks via telephone lines or ISDN with dynamic IP address assignment (DHCP). Motorola ISG Equipment Among the equipment designed to work with X.25 and Frame Relay, the most interesting are the products manufactured by the Motorola Corporation Information Systems Group (Motorola ISG). Unlike backbone devices used in global data networks (Northern Telecom, Sprint, Alcatel, etc.), Motorola equipment is capable of operating completely autonomously, without a special network management center. The range of capabilities important for use in corporate networks is much wider for Motorola equipment. Of particular note are the developed means of hardware and software modernization, which make it possible to easily adapt the equipment to specific conditions. All Motorola ISG products can operate as X.25/Frame Relay switches, multi-protocol access devices (PAD, FRAD, SLIP, PPP, etc.), support Annex G (X.25 over Frame Relay), provide SNA protocol conversion (SDLC/ QLLC/RFC1490). Motorola ISG equipment can be divided into three groups, differing in the set of hardware and scope of application.

The first group, intended to work as peripheral devices, makes up the Vanguard series. It includes Vanguard 100 (2-3 ports) and Vanguard 200 (6 ports) serial access nodes, as well as Vanguard 300/305 routers (1-3 serial ports and an Ethernet/Token Ring port) and Vanguard 310 ISDN routers. Routers Vanguard, in addition to a set of communication capabilities, includes the transmission of IP, IPX and Appletalk protocols over X.25, Frame Relay and PPP. Naturally, at the same time, the gentleman’s set necessary for any modern router is supported - the RIP and OSPF protocols, filtering and access restriction tools, data compression, etc.

The next group of Motorola ISG products includes the Multimedia Peripheral Router (MPRouter) 6520 and 6560 devices, which differ mainly in performance and expandability. In the basic configuration, the 6520 and 6560 have, respectively, five and three serial ports and an Ethernet port, and the 6560 has all high-speed ports (up to 2 Mbps), and the 6520 has three ports with speeds up to 80 kbps. MPRouter supports all communication protocols and routing capabilities available for Motorola ISG products. The main feature of MPRouter is the ability to install a variety of additional fees, which is reflected by the word Multimedia in its name. There are serial port cards, Ethernet/Token Ring ports, ISDN cards, and Ethernet hub. The most interesting feature of MPRouter is voice over Frame Relay. To do this, special boards are installed in it, allowing the connection of conventional telephone or fax machines, as well as analog (E&M) and digital (E1, T1) PBXs. The number of simultaneously serviced voice channels can reach two or more dozen. Thus, MPRouter can be used simultaneously as a voice and data integration tool, a router and an X.25/Frame Relay node.

The third group of Motorola ISG products is backbone equipment for global networks. These are expandable devices of the 6500plus family, with fault-tolerant design and redundancy, designed to create powerful switching and access nodes. They include various sets of processor modules and I/O modules, allowing for high-performance nodes with from 6 to 54 ports. In corporate networks, such devices can be used to build complex systems with a large number of connected resources.

It is interesting to compare Cisco and Motorola routers. We can say that for Cisco routing is primary, and communication protocols are only a means of communication, while Motorola focuses on communication capabilities, considering routing as another service implemented using these capabilities. In general, the routing capabilities of Motorola products are poorer than those of Cisco, but they are quite sufficient for connecting end nodes to the Internet or a corporate network.

The performance of Motorola products, all other things being equal, is perhaps even higher, and at a lower price. Thus, Vanguard 300, with a comparable set of capabilities, turns out to be approximately one and a half times cheaper than its closest analogue, Cisco 2501.

Eicon Technology Solutions

In many cases, it is convenient to use solutions from the Canadian company Eicon Technology as peripheral equipment for corporate networks. The basis of Eicon solutions is the universal communication adapter EiconCard, which supports a wide range of protocols - X.25, Frame Relay, SDLC, HDLC, PPP, ISDN. This adapter is installed in one of the computers on the local network, which becomes a communication server. This computer can be used for other tasks as well. This is possible due to the fact that EiconCard has enough powerful processor and its own memory and is capable of processing network protocols without loading the communication server. Eicon software allows you to build both gateways and routers based on EiconCard, running almost all operating systems on Intel platform. Here we will look at the most interesting of them.

The Eicon family of solutions for Unix includes the IP Connect Router, X.25 Connect Gateways and SNA Connect. All of these products can be installed on a computer running SCO Unix or Unixware. IP Connect allows IP traffic to be carried over X.25, Frame Relay, PPP or HDLC and is compatible with equipment from other manufacturers, including Cisco and Motorola. The package includes a Firewall, data compression tools and SNMP management tools. The main application of IP Connect is connecting application servers and Unix-based Internet servers to a data network. Naturally, the same computer can also be used as a router for the entire office in which it is installed. There are a number of advantages to using an Eicon router instead of pure hardware devices. Firstly, it is easy to install and use. From point of view operating system EiconCard with IP Connect installed looks like just another network card. This makes setting up and administering IP Connect fairly simple for anyone who has been around Unix. Secondly, directly connecting the server to the data network allows you to reduce the load on the office LAN and provide that very single point of connection to the Internet or to the corporate network without installing additional network cards and routers. Third, this "server-centric" solution is more flexible and extensible than traditional routers. There are a number of other benefits that come with using IP Connect with other Eicon products.

X.25 Connect is a gateway that allows LAN applications to communicate with X.25 resources. This product allows you to connect Unix users and DOS/Windows and OS/2 workstations to remote systems Email, databases and other systems. By the way, it should be noted that Eicon gateways today are perhaps the only common product on our market that implements the OSI stack and allows you to connect to X.400 and FTAM applications. In addition, X.25 Connect allows you to connect remote users to a Unix machine and terminal applications on local network stations, as well as organize interaction between remote Unix computers via X.25. Using standard Unix capabilities together with X.25 Connect, it is possible to implement protocol conversion, i.e. translation of Unix Telnet access into an X.25 call and vice versa. It is possible to connect a remote X.25 user using SLIP or PPP to a local network and, accordingly, to the Internet. In principle, similar protocol translation capabilities are available in Cisco routers running IOS Enterprise software, but the solution is more expensive than Eicon and Unix products combined.

Another product mentioned above is SNA Connect. This is a gateway designed to connect to the IBM mainframe and AS/400. It is typically used in conjunction with user software—5250 and 3270 terminal emulators and APPC interfaces—also manufactured by Eicon. Analogues of the solutions discussed above exist for other operating systems - Netware, OS/2, Windows NT and even DOS. Particularly worth mentioning is Interconnect Server for Netware, which combines all of the above capabilities with remote configuration and administration tools and a client authorization system. It includes two products - Interconnect Router, which allows routing IP, IPX and Appletalk and is, from our point of view, the most successful solution for interconnection remote networks Novell Netware, and Interconnect Gateway, which provides, among other things, powerful SNA connectivity. Another Eicon product designed to work in the Novell Netware environment is WAN Services for Netware. This is a set of tools that allow you to use Netware applications on X.25 and ISDN networks. Using it in conjunction with Netware Connect allows remote users to connect to the LAN via X.25 or ISDN, as well as provide X.25 egress from the LAN. There is an option to ship WAN Services for Netware with Novell's Multiprotocol Router 3.0. This product is called Packet Blaster Advantage. A Packet Blaster ISDN is also available, which works not with the EiconCard, but with ISDN adapters also supplied by Eicon. In this case, various connection options are possible - BRI (2B+D), 4BRI (8B+D) and PRI (30B+D). WAN Services for NT is designed to work with Windows NT applications. It includes IP Router, tools for connecting NT applications to X.25 networks, support for Microsoft SNA Server, and tools for remote user access via X.25 in local network using Remote Access Server. An Eicon ISDN adapter can also be used in conjunction with ISDN Services for Netware software to connect a Windows NT server to an ISDN network.

Methodology for building corporate networks.

Now that we have listed and compared the main technologies that a developer can use, let's move on to the basic issues and methods used in network design and development.

Network requirements.

Network designers and network administrators always strive to ensure that three basic network requirements are met:

scalability;

performance;

controllability.

Good scalability is necessary so that both the number of users on the network and the application software can be changed without much effort. High network performance is required for most modern applications to function properly. Finally, the network must be manageable enough to be reconfigured to meet the organization's ever-changing needs. These requirements reflect a new stage in the development of network technologies - the stage of creating high-performance corporate networks.

Uniqueness of new software and technology complicates the development of enterprise networks. Centralized resources, new classes of programs, different principles of their application, changes in the quantitative and qualitative characteristics of the information flow, an increase in the number of concurrent users and an increase in the power of computing platforms - all these factors must be taken into account in their entirety when developing a network. Nowadays there are a large number of technological and architectural solutions on the market, and choosing the most suitable one is a rather difficult task.

In modern conditions, for proper network design, development and maintenance, specialists must consider the following issues:

o Change of organizational structure.

When implementing a project, you should not “separate” software specialists and network specialists. When developing networks and the entire system as a whole, you need united team from specialists of various profiles;

o Use of new software tools.

It is necessary to become familiar with new software at an early stage of network development so that the necessary adjustments can be made in a timely manner to the tools planned for use;

o Research different solutions.

It is necessary to evaluate various architectural decisions and their possible impact on the operation of the future network;

o Checking networks.

It is necessary to test the entire network or parts of it in the early stages of development. To do this, you can create a network prototype that will allow you to evaluate the correctness of the decisions made. This way you can prevent the emergence of various kinds of bottlenecks and determine the applicability and approximate performance of different architectures;

o Selection of protocols.

To choose the right network configuration, you need to evaluate the capabilities various protocols. It is important to determine how network operations that optimize the performance of one program or software package may affect the performance of others;

o Selecting a physical location.

When choosing a location to install servers, you must first determine the location of the users. Is it possible to move them? Will their computers be connected to the same subnet? Will users have access to the global network?

o Calculation of critical time.

It is necessary to determine the acceptable response time of each application and possible periods maximum load. It is important to understand how emergency situations can affect network performance and determine whether a reserve is needed to organize the continuous operation of the enterprise;

o Analysis of options.

It is important to analyze the different uses of software on the network. Centralized storage and processing of information often creates additional load at the center of the network, and distributed computing may require the strengthening of local workgroup networks.

Today there is no ready-made, streamlined universal methodology, following which you can automatically carry out the entire range of activities for the development and creation of a corporate network. First of all, this is due to the fact that there are no two absolutely identical organizations. In particular, each organization is characterized by a unique leadership style, hierarchy, and business culture. And if we take into account that the network inevitably reflects the structure of the organization, then we can safely say that no two identical networks exist.

Network architecture

Before you begin building a corporate network, you must first determine its architecture, functional and logical organization, and take into account the existing telecommunications infrastructure. A well-designed network architecture helps evaluate the feasibility of new technologies and applications, serves as a foundation for future growth, guides the choice of network technologies, helps avoid unnecessary costs, reflects the connectivity of network components, significantly reduces the risk of incorrect implementation, etc. The network architecture forms the basis of the technical specifications for the created network. It should be noted that network architecture differs from network design in that it does not, for example, define the exact schematic diagram networks and does not regulate the placement of network components. Network architecture, for example, determines whether some parts of the network will be built on Frame Relay, ATM, ISDN, or other technologies. The network design must contain specific instructions and estimates of parameters, for example, the required throughput value, the actual bandwidth, the exact location of communication channels, etc.

There are three aspects, three logical components, in the network architecture:

principles of construction,

network templates

and technical positions.

Design principles are used in network planning and decision making. Principles are a set simple instructions, which describe in sufficient detail all the issues of constructing and operating a deployed network over a long period of time. As a rule, the formation of principles is based on the corporate goals and basic business practices of the organization.

The principles provide the primary link between corporate development strategy and network technologies. They serve to develop technical positions and network templates. When developing a technical specification for a network, the principles of constructing a network architecture are set out in a section that defines the general goals of the network. The technical position can be viewed as a target description that determines the choice between competing alternative network technologies. The technical position clarifies the parameters of the selected technology and provides a description of a single device, method, protocol, service provided, etc. For example, when choosing a LAN technology, speed, cost, quality of service, and other requirements must be taken into account. Developing technical positions requires in-depth knowledge of networking technologies and careful consideration of the organization's requirements. The number of technical positions is determined by the given level of detail, the complexity of the network and the size of the organization. The network architecture can be described in the following technical terms:

Network transport protocols.

What transport protocols should be used to transfer information?

Network routing.

What routing protocol should be used between routers and ATM switches?

Quality of service.

How will the ability to choose the quality of service be achieved?

Addressing in IP networks and addressing domains.

What addressing scheme should be used for the network, including registered addresses, subnets, subnet masks, forwarding, etc.?

Switching in local networks.

What switching strategy should be used in local area networks?

Combining switching and routing.

Where and how switching and routing should be used; how should they combine?

Organization of a city network.

How should branches of an enterprise located, say, in the same city communicate?

Organization of a global network.

How should enterprise branches communicate over a global network?

Remote access service.

How do users of remote branches gain access to the enterprise network?

Network patterns are a set of models of network structures that reflect the relationships between network components. For example, for a particular network architecture, a set of templates is created to “reveal” the network topology of a large branch or wide area network, or to show the distribution of protocols across layers. Network patterns illustrate a network infrastructure that is described by a complete set of technical positions. Moreover, in a well-designed network architecture, network templates can be as close in content to technical items as possible in terms of detail. In fact, network templates are a description of the functional diagram of a network section that has specific boundaries; the following main network templates can be distinguished: for a global network, for a metropolitan network, for a central office, for a large branch of an organization, for a department. Other templates can be developed for sections of the network that have any special features.

The described methodological approach is based on studying a specific situation, considering the principles of building a corporate network in their entirety, analyzing its functional and logical structure, developing a set of network templates and technical positions. Various implementations of corporate networks may include certain components. In general, a corporate network consists of various branches connected by communication networks. They can be wide area (WAN) or metropolitan (MAN). Branches can be large, medium and small. A large department can be a center for processing and storing information. A central office is allocated from which the entire corporation is managed. Small departments include various service departments (warehouses, workshops, etc.). Small branches are essentially remote. The strategic purpose of the remote branch is to house sales and technical support closer to the consumer. Customer communications, which significantly impact corporate revenue, will be more productive if all employees have the ability to access corporate data at any time.

At the first step of building a corporate network, the proposed functional structure is described. The quantitative composition and status of offices and departments is determined. The necessity of deploying our own private communication networks or a service provider is selected that is able to meet the requirements. The development of a functional structure is carried out taking into account the financial capabilities of the organization, long-term development plans, the number of active network users, running applications, and the required quality of service. The development is based on the functional structure of the enterprise itself.

The second step is to determine the logical structure of the corporate network. The logical structures differ from each other only in the choice of technology (ATM, Frame Relay, Ethernet...) for building the backbone, which is the central link of the corporation’s network. Let's consider logical structures built on the basis of cell switching and frame switching. The choice between these two methods of transmitting information is made based on the need to provide guaranteed quality of service. Other criteria may be used.

The data transmission backbone must satisfy two basic requirements.

o The ability to connect a large number of low-speed workstations to a small number of powerful, high-speed servers.

o Acceptable speed of response to customer requests.

An ideal highway should have high reliability of data transmission and a developed control system. A management system should be understood, for example, as the ability to configure the backbone taking into account all local features and maintaining reliability at such a level that even if some parts of the network fail, the servers remain available. The listed requirements will probably determine several technologies, and the final choice of one of them remains with the organization itself. You need to decide what is most important - cost, speed, scalability or quality of service.

The logical structure with cell switching is used in networks with real-time multimedia traffic (video conferencing and high-quality voice transmission). At the same time, it is important to soberly assess how necessary such an expensive network is (on the other hand, even expensive networks are sometimes not able to satisfy some requirements). If this is so, then it is necessary to take as a basis logical structure frame switching networks. The logical switching hierarchy, combining two levels of the OSI model, can be represented as a three-level diagram:

The lower level is used to combine local Ethernet networks,

The middle layer is either an ATM local network, a MAN network, or a WAN backbone communication network.

The top level of this hierarchical structure is responsible for routing.

The logical structure allows you to identify all possible communication routes between individual sections of the corporate network

Backbone based on cell switching

When mesh switching technology is used to build a network backbone, the interconnection of all workgroup-level Ethernet switches is carried out by high-performance ATM switches. Operating at Layer 2 of the OSI reference model, these switches transmit 53-byte fixed-length cells instead of variable-length Ethernet frames. This networking concept implies that the Ethernet level switch working group must have an ATM segment-and-assemble (SAR) output port that converts variable-length Ethernet frames into fixed-length ATM cells before forwarding the information to the ATM backbone switch.

For wide area networks, core ATM switches are capable of connecting remote regions. Also operating at Layer 2 of the OSI model, these WAN switches can use T1/E1 links (1.544/2.0Mbps), T3 links (45Mbps) or SONET OC-3 links (155Mbps). To provide urban communications, a MAN network can be deployed using ATM technology. The same backbone network ATM can be used to communicate between telephone exchanges. In the future, as part of the client/server telephony model, these stations may be replaced by voice servers on the local network. In this case, the ability to guarantee quality of service in ATM networks becomes very important when organizing communications with client personal computers.

Routing

As already noted, routing is the third and highest level in the hierarchical structure of the network. Routing, which operates at Layer 3 of the OSI reference model, is used to organize communication sessions, which include:

o Communication sessions between devices located in different virtual networks (each network is usually a separate IP subnet);

o Communication sessions that pass through wide area/city

One strategy for building a corporate network is to install switches at lower levels shared network. Local networks are then connected using routers. Routers are required to divide a large organization's IP network into many separate IP subnets. This is necessary to prevent "broadcast explosion" associated with protocols such as ARP. To contain the spread of unwanted traffic across the network, all workstations and servers must be divided into virtual networks. In this case, routing controls communication between devices belonging to different VLANs.

Such a network consists of routers or routing servers (logical core), a network backbone based on ATM switches and a large number of Ethernet switches located on the periphery. With the exception of special cases, such as video servers that connect directly to the ATM backbone, all workstations and servers must be connected to Ethernet switches. This type of network construction will allow you to localize internal traffic within workgroups and prevent such traffic from being pumped through backbone ATM switches or routers. The aggregation of Ethernet switches is carried out by ATM switches, usually located in the same compartment. It should be noted that multiple ATM switches may be required to provide enough ports to connect all the Ethernet switches. As a rule, in this case, 155 Mbit/s communication is used over multimode fiber optic cable.

Routers are located away from the backbone ATM switches, since these routers need to be moved beyond the routes of the main communication sessions. This design makes routing optional. This depends on the type of communication session and the type of traffic on the network. Routing should be avoided when transmitting real-time video information, as it can introduce unwanted delays. Routing is not needed for communication between devices located on the same virtual network, even if they are located in different buildings within a large enterprise.

In addition, even in situations where routers are required for certain communications, placing routers away from backbone ATM switches can minimize the number of routing hops (a routing hop is the portion of the network from a user to the first router or from one router to another). This not only reduces latency, but also reduces the load on routers. Routing has become widespread as a technology for connecting local networks in a global environment. Routers provide a variety of services designed for multi-level control of the transmission channel. This includes a general addressing scheme (at the network layer) that is independent of how the addresses of the previous layer are formed, as well as conversion from one control layer frame format to another.

Routers make decisions about where to route incoming data packets based on the network layer address information they contain. This information is retrieved, analyzed, and compared with the contents of routing tables to determine which port a particular packet should be sent to. The link layer address is then extracted from the network layer address if the packet is to be sent to a segment of a network such as Ethernet or Token Ring.

In addition to processing packets, routers simultaneously update routing tables, which are used to determine the destination of each packet. Routers create and maintain these tables dynamically. As a result, routers can automatically respond to changes in network conditions, such as congestion or damage to communication links.

Determining a route is quite a difficult task. In a corporate network, ATM switches must function in much the same way as routers: information must be exchanged based on the network topology, available routes, and transmission costs. The ATM switch critically needs this information to select the best route for a particular communication session initiated by end users. In addition, determining a route is not limited to just deciding on the path along which a logical connection will pass after generating a request for its creation.

The ATM switch can select new routes if for some reason the communication channels are unavailable. At the same time, ATM switches must provide network reliability at the router level. To create a highly scalable network economic efficiency, it is necessary to transfer routing functions to the periphery of the network and ensure traffic switching in its backbone. ATM is the only network technology that can do this.

To select a technology, you need to answer the following questions:

Does the technology provide adequate quality of service?

Can she guarantee the quality of service?

How expandable will the network be?

Is it possible to choose a network topology?

Are the services provided by the network cost-effective?

How effective will the management system be?

The answers to these questions determine the choice. But, in principle, they can be used in different parts of the network different technologies. For example, if certain areas require support for real-time multimedia traffic or a speed of 45 Mbit/s, then ATM is installed in them. If a section of the network requires interactive processing of requests, which does not allow significant delays, then it is necessary to use Frame Relay, if such services are available in this geographic area (otherwise, you will have to resort to the Internet).

Thus, a large enterprise may connect to the network via ATM, while branch offices connect to the same network via Frame Relay.

When creating a corporate network and selecting network technology with appropriate software and hardware, the price/performance ratio must be taken into account. It's hard to expect high speeds from cheap technologies. On the other hand, it makes no sense to use the most complex technologies for the simplest tasks. Different technologies should be properly combined to achieve maximum efficiency.

When choosing a technology, the type of cabling system and the required distances should be taken into account; compatibility with already installed equipment (significant cost minimization can be achieved if new system it is possible to turn on already installed equipment.

Generally speaking, there are two ways to build a high-speed local network: evolutionary and revolutionary.

The first way is based on expanding the good old frame relay technology. The speed of the local network can be increased within the framework of this approach by upgrading the network infrastructure, adding new communication channels and changing the method of packet transmission (which is what is done in switched Ethernet). Regular Ethernet network shares bandwidth, that is, the traffic of all network users competes with each other, claiming the entire bandwidth of the network segment. Switched Ethernet creates dedicated routes, giving users real bandwidth of 10 Mbit/s.

The revolutionary path involves the transition to radically new technologies, for example, ATM for local networks.

Extensive practice in building local networks has shown that the main issue is quality of service. This is what determines whether the network can work successfully (for example, with applications such as video conferencing, which are increasingly used around the world).

Conclusion.

Whether or not to have your own communication network is a “private matter” for each organization. However, if building a corporate (departmental) network is on the agenda, it is necessary to conduct a deep, comprehensive study of the organization itself, the problems it solves, draw up a clear document flow chart in this organization and, on this basis, begin to select the most appropriate technology. One example of building corporate networks is the currently widely known Galaktika system.

List of used literature:

1. M. Shestakov “Principles of building corporate data networks” - “Computerra”, No. 256, 1997

2. Kosarev, Eremin “Computer systems and networks”, Finance and Statistics, 1999.

3. Olifer V. G., Olifer N. D. “Computer networks: principles, technologies, protocols”, St. Petersburg, 1999

4. Materials from the site rusdoc.df.ru

Lecture No. 1.

The concept of networks. Corporate information systems. Structure and purpose of the CIS. Characteristic. Requirements for organizing a CIS. Processes. Multi-level organization of CIS.

The concept of networks. What is a network?

As is known, the first Personal Computers (PCs) intended for solving mathematical problems. However, it soon became obvious that the main area of ​​their application should be information processing, in which personal computers can no longer work in standalone mode, but must interact with other PCs, with sources and consumers of information. The result of this was And informational V computing With eti ( IVS), which have now become widespread in the world.

Network- two (or more) computers and devices connected to them, connected by means of communication.

Server - This:

Ø A network OS component that provides clients with access to network resources. For each type of resource on the network, one or more servers can be created. The most commonly used servers are file servers, print servers, database servers, remote access servers, etc.

Ø A computer that runs the server program and shares its resources on the network.

Server-based network - a network in which the functions of computers are differentiated into those of servers and clients. It has become the standard for networks serving more than 10 users.

Peer-to-peer network - a network in which there are no dedicated servers or hierarchy of computers. All computers are considered equal. Typically, each computer acts as both a server and a client.

Client - any computer or program that connects to the services of another computer or program. For example, Windows 2000 Professional is a client Active Directory. The term also sometimes refers to software that allows a computer or program to create a connection. For example, to connect a Windows 95 computer to Active Directory on a Windows 2000 computer, you must install the Active Directory Client for Windows 95 on the first computer.

The network consists of:

Ø hardware (servers, workstations, cables, printers, etc.)

Ø Protection of data and resources from unauthorized access;

Ø Issuance of certificates about information and software resources;

Ø Automation of programming and distributed processing – parallel execution of a task by several PCs.

Message delivery time– statistical average time from the moment a message is transmitted to the network until the message is received by the addressee.

Network performance– total productivity of host computers (servers). In this case, the performance of host computers (servers) usually means the nominal performance of their processors.

Data processing cost– is formed taking into account the means used for input/output, transmission, storage and processing of data. Based on prices calculated data processing cost, which depends on the amount of computer network resources used (amount of transmitted data, processor time), as well as on the mode of data transmission and processing.

The characteristics depend on the structural and functional organization of the network, the main of which are:

Ø Topology (structure) of the CIS (PC composition, structure of the basic SPD and terminal network),

Ø Data transmission method in the core network,

Ø Methods for establishing connections between interacting users,

Ø Selection of data transmission routes.

Ø Load created by users.

Topology - physical structure and network organization. The most common topologies are:

Ø highway,

Ø wood,

determined by the number of active users and the intensity of user interaction with the network. The last parameter is characterized by the amount of data input and output by the PC per unit of time, and the need for resources of the main machines to process this data.

Requirements for organizing a CIS.

The CIS organization must satisfy the following basic requirements:

1) Openness – this is the ability to include additional host computers (servers), terminals, PCs, nodes and communication lines without changing the hardware and software of the existing components,

2) Flexibility – the ability to operate any host computers (servers) with terminals or PCs of various types, the permissibility of changing the type of PC and communication lines,

3) Reliability – maintaining operability when the structure changes as a result of failure of the PC, nodes and communication lines,

4) Efficiency - ensuring the required quality of user service at minimal cost,

5) Safety - software or hardware-software means of protecting in one way or another information that is processed and transmitted on the network

These requirements are implemented through the modular principle of organizing process management in the network according to a multi-level scheme, which is based on the concepts of process, control level, interface and protocol.

Processes.

The functioning of the CIS is presented in terms of processes.

Process is a dynamic object that implements a purposeful act of data processing. Processes are divided into two classes:

Ø Applied

Ø System

Application process - execution of an application or processing program of a PC operating system, as well as the functioning of a PC, i.e., a user working on a PC.

System process – execution of a program (algorithm) that implements an auxiliary function associated with supporting application processes. For example, activating a PC or terminal for an application process, organizing communication between processes. The process model is shown in Figure 1.2

A process is generated by a program or user and is associated with data that comes from outside as input and is generated by the process for external use. The input of data required by the process and the output of data are made in the form messages – sequences of data that have a complete semantic meaning. Messages are entered into the process and messages are output from the process through logical (programmatically organized) points called ports. Ports are divided into input And weekend.

Thus, a process as an object is represented by a set of ports through which it interacts with other processes on the network.

The interaction of processes comes down to the exchange of messages that are transmitted through channels created by network tools (Figure 1.3).

The period of time during which processes interact is called session (session). In a CIS, the only form of interaction between processes is the exchange of messages. In PCs and computing systems, interaction between processes is ensured through access to data common to them, shared memory, and the exchange of interrupt signals.

This difference is due to the territorial distribution of processes in the CIS, as well as the fact that communication channels are used to physically interface network components, which ensure the transmission of messages, but not individual signals.

Multi-level network organization.

The transmission medium of the network can have any physical nature and be a set of wired fiber-optic, radio relay, tropospheric, satellite communication lines (channels). In each of the network systems there is a certain set of processes. Processes distributed across different systems interact through the transmission medium by exchanging messages.

To ensure openness, reliability, flexibility, efficiency and security of the network, process management is organized according to a multi-level scheme (Figure 1.4). Open System Integration (hereinafter referred to as OSI) O pen S system I integration) describes a model representing general concepts to define network components. The OSI model is typically used when planning a complete set of network protocols.

In table 1.1 presents the approach used when using the OSI model. The process of creating network communications is divided into seven stages.

Table 1.1

In each of the systems, rectangles indicate software and hardware modules that implement certain functions of data processing and transmission.

The modules are distributed across levels 1…7. Level 1 is the bottom, level 7 is the top. A module of level N physically interacts only with modules of neighboring levels N+1 and N-1. The level 1 module interacts with the transmission medium, which can be considered as a level 0 (zero) object. Application processes are usually classified as the top level of the hierarchy, in this case level 7. Physical communication between processes is provided by the transmission medium. The interaction of applied processes with the transmitting environment is organized using six intermediate control levels 1...6, which we will consider starting from the bottom.

Level 1 – physical - implements control of the communication channel, which comes down to connecting and disconnecting the communication channel and generating signals representing the transmitted data. Due to the presence of interference, distortions are introduced into the transmitted data and the reliability of the transmission is reduced: the probability of error is 10-4..

Level 2 – datalink/data link– ensures reliable data transmission through a physical channel organized at level 1. The probability of data corruption is 10-8. If an error is detected, the data is re-queried.

Level 3 – network – provides data transmission through the core data network (DTN). Network management at this level consists of choosing a data transmission route along the lines connecting network nodes.

Levels 1…3 organize basic data transmission between network users.

Level 4 – transport – implements procedures for pairing network users (main and personal computers) with the base data transmission system. At this level, it is possible to interface various systems with the network, and thereby organize transport service for data exchange between the network and network systems.

Level 5 – sessional - organizes communication sessions for the period of interaction between processes. At this level, based on process requests, ports for receiving and transmitting messages and organizing connections - logical channels.

Level 6 – representation - translates various languages, data formats and codes for the interaction of different types of PCs equipped with specific operating systems and operating in different codes between themselves and PCs and terminals of different types. The interaction of processes is organized on the basis standard forms representation of tasks and data sets. Presentation layer procedures interpret standard messages in relation to specific systems - PCs and terminals. This makes it possible for one program to interact with different types of PCs.

Level 7 – applied (applications) – created only to perform a specific data processing function without taking into account the network structure, type of communication channels, methods of choosing routes, etc. This ensures the openness and flexibility of the system.

The number of layers and the distribution of functions between them significantly influence the complexity of the software of the PCs included in the network and the efficiency of the network. The considered seven-level model ( reference model interaction open systems– EMVOS), called open systems architecture, adopted as a standard by the International Organization for Standardization (IOS) and is used as the basis for the development of CIS and IVS in general.

To help you master the subject, here are the trap words, the first characters of which coincide with the names of the levels in the same order:

People

Seem (Seems)

Need

Data

Processing (All people seem to need data processing.)

This key phrase is easy to remember and will help the local network administrator feel responsible.

Literature

« Information processes V computer networks. Protocols, standards, interfaces, models...” - M: KUDITS-OBRAZ, 1999, Preface. Introduction, Chapter 1, Page 3-12;

“Information processes in computer networks. Protocols, standards, interfaces, models..." - M: KUDITS-OBRAZ, 1999, Chapter 7, Page. 72-75

Sportak M et al. “High-performance networks. User Encyclopedia”, Trans. from English, - K: DiaSoft Publishing House, 1998, Chapter 29, Page. 388-406

Heywood Drew "Inner World"Windows NT Server4" Per. from English, - K.: Publishing house "Dia-Soft", 1997, Chapter 9, Page. 240-242; Appendix A, Page 488-489

The concept of “corporate communication system” has long been established and entrenched. Moreover, it is so strong that we often stopped even thinking about its semantic (they also say semantic) content. On the eve of the autumn conference “Corporate communication systems - lessons from convergence”, organized by our magazine, we propose to expand our understanding of the communication networks of enterprises and institutions, and at the same time think about further ways of their development and improvement.

And since there are probably as many points of view on corporate networks and systems as there are people involved in them, we considered it reasonable to turn directly to the “primary sources” and find out what meaning the leading Ukrainian experts give to this concept and what the collective mind of humanity thinks about this, called the Internet.

We asked the experts whose opinions are posted in the boxes to concentrate their answers on the definition of the term “corporate communication system” and the directions of its migration at the present time.

ABOUT obviously corporate network - This is, first of all, an enterprise network. Unlike the operator's network or home network. The purpose of these networks is different. By at least, corporate communication systems are designed to serve enterprise employees and do not provide any services to third-party organizations and citizens (except for personal telephone calls and the use world wide web for non-production purposes). An enterprise can be large or small, profitable or unprofitable, consisting of a single office or many branches in one country or around the world. When is it correct to talk about a corporate network, and when is it not? After all, in a small enterprise on one site we will be dealing with a relatively simple network. And if an enterprise has many geographically distributed branches, then the network can acquire a very complex architecture and developed service capabilities.

To resolve all these doubts, let's turn to the origins. Term "corporation" comes from Latin corporatio - association . Therefore, if an enterprise consists of one office and there is nothing else to combine in it except computers and printers, then there seems to be no need to talk about a corporation.

But let's remember that the concept of “corporate communication system”, or “corporate network” (enterprise network), came to us from the West. Before this, the domestic term “ institutional or industrial communication systems " The appearance in those days of the term UPBX (institutional and industrial automatic telephone exchange) once again indicates that we are talking about enterprise networks.

Intuitively, we all understand somewhere what a corporate network is. But sometimes it is useful to plunge into more subtle philological and linguistic areas. After all, the hour is uneven and it may turn out that many concepts are used by us only because “everyone says so,” nothing more, and their innermost meaning has long been lost.

In this regard, we will try to understand the etymology of the term “corporate communication network”. What is a corporation? The Internet provides many definitions of a corporation. Let's choose the most interesting ones.

Corporation [Latin corporatio - association, community] - a form of organization of business activity that provides for shared ownership of participants, independent legal status and concentration of management functions in the hands of professional managers (managers) working for hire. There are public and private corporations.

This is probably the simplest and most accessible definition. Here's one more thing though.

Corporation (legal) - a general name for many types of unions that have an internal organization that unites the members of the union into one whole, which is the subject of rights and obligations, legal entity. The expressive force of the corporation's will is the general meeting of its members, and the executive body is the board. There are public and private law corporations. The first include territorial unions, for example, urban, rural communities, local class unions; the second includes trade unions, commercial and industrial societies, etc., operating on the basis of special charters.

The legal definition expands quite well on the previous one.

A corporation (in social psychology) is an organized group characterized by isolation, maximum centralization and authoritarian leadership, opposing itself to other social communities on the basis of its narrowly individualistic and narrow group interests. Interpersonal relationships in a corporation are mediated by asocial and often antisocial value orientations. The personalization of an individual in a corporation is carried out through the depersonalization of other individuals.

It needs to be twisted like this. It sounds like an indictment from a prosecutor (God forbid).

So, a corporation is an association. Moreover, the association of companies, branches, structural divisions and even employees of one enterprise. In other words, corporate network - really a synonym enterprise networks .

Here I would like to make an important caveat. In everyday practice we often talk about enterprise-scale networks, divisions or department. It is understood that for such networks various technical solutions, equipment and software. Note: this is a slightly different terminological layer that does not intersect with the subject of this article.

Corporate communication network

Having decided on the concept of a corporation, let’s move on to communication networks .

Communication network - a set of terminal devices (communication terminals) united by information transmission channels and switching devices (network nodes) that ensure the exchange of messages between all terminal devices.

However, it would not be entirely correct to talk about the communication network as a whole and not mention the type of information transmitted over this network. Ultimately, all existing networks are designed to transmit a certain type (or several types) of information. Enterprises most often build local area networks (LANs) and telephone networks, each of which uses its own hardware resources.

At the same time, the idea of ​​convergence, having captured the minds of engineers and equipment developers, gathered around itself advocates of comprehensive integration. The brainchild of this idea was multiservice networks, built on the winning concept of using packet networks to transmit multimedia traffic. Therefore, when talking about a corporate network, you should clarify what type of information will be transmitted on this network - data, voice, video traffic, etc. By the way, the concept of a corporate network is closely related to the idea of ​​systems integration, as an integrated approach to automating the design, production and creation of (corporate) information networks, requiring the solution of technical problems and the implementation of organizational measures.

Large corporate communication systems unite geographically distributed divisions or branches of an enterprise. But if there is only one branch, this is just a simpler, degenerate case. In this case, a corporate network can be intended for data transmission, voice, or be multi-service. It is obvious that the services available on branch networks (Internet, e-mail, voice mail, telephony, file transfer, etc.) must be fully implemented in the corporate communication network. Otherwise, it is hardly true to say that the corporate network fully possesses this or that functionality.

So, the result of researching the issue can be a definition that incorporates the points of view of experts, and opinions borrowed from the Internet, and one’s own reasoning, namely:

A corporate network (also known as a departmental network) is a communication network used to transmit various types of information within a company or group of companies (corporation) and is not used to provide commercial communication services to third parties and individuals. Such networks are deployed both on the basis of their own infrastructure and using resources provided by telecommunications operators.

What should a corporate communication network be like?

Why does an enterprise need a communication network at all? The question is rhetorical. Probably in order to provide employees of the enterprise with the opportunity perform your duties productively . This is especially true in the presence of an aggressive competitive environment. A high-quality communication system increases labor productivity through the implementation of a wide range of various services, as well as by ensuring the effective functioning of the enterprise’s information infrastructure.

Architecture And possibilities corporate network depends on the tasks assigned to it, on the size of the enterprise and the specifics of its activities, as well as on the prospects for further expansion. Currently, the corporate network of a small enterprise contains, as a rule, one or two components - telephone and data transmission. Moreover, telephone services can be provided directly through a local telecommunications operator (without installing a PBX), and computers are connected to a small local network with Internet access in any available way.

We see that telephony And data transfer in small enterprises they are initially separated. As the enterprise grows, each network evolves, but remains independent of each other. A PBX is added, servers and databases appear, firewalls and call centers. But voice still (for the time being) remains separated from data transmission.

Proponents of unification will rightly note that there are many solutions for small SOHO-level enterprises that involve the use of IP channels for both telephony and data transmission. Indeed, such solutions can be quite effective, for example, when organizing a remote office. But we will come to this issue a little later.

Despite the well-known conservatism of employees of technical departments of enterprises, the principles convergence , the use of a single medium to transmit heterogeneous traffic is finding more and more adherents. But are all enterprises ready to implement a single multiservice network? Most likely the answer will be no. And, by and large, this is not a question at all. After all, often an enterprise has already built two separate networks, each based on traditional native architecture and equipment. In most cases, there is no talk of using a single IP environment for voice and data transmission within an enterprise. To make such a decision there must be either sufficiently significant economic arguments , or arguments of a different kind - convenience, savings on maintenance, anything else.

Enterprise networks of the future

If we are talking only about data transmission and telephony services, then we ourselves are undoubtedly in captivity of old paradigms. After all, the list of services that can be organized and provided to subscribers of a corporate network is much wider. It is worth recalling video conferencing systems, a single universal mailbox (Unified Messaging), and the DECT microcellular communication system. Currently, the issue of convergence of mobile and fixed communication services is quite acute, especially since many manufacturers offer such solutions both at the operator and corporate levels (see publications in SIB, 2006, No. 4, p. 78 - 81, “New Horizons of Corporate Communications”, as well as “SiB”, 2006, No. 4, pp. 82–85, “FMC, or the New Paradigm of the Convergence Era”). After some time, it will be appropriate to talk about the use of Wi MAX in corporate networks.

The corporate network of the future is an integrated environment that provides various types of services - traditional data transmission, telephony, video conferencing and video broadcasting, access control, security and video surveillance. Necessary components of a corporate network are mobile access tools and advanced data transmission security tools.

When discussing the feasibility of certain solutions proposed by manufacturers, first of all we should talk about the possibility and efficiency of fulfilling the production tasks that the enterprise faces. It is obvious that the problems solved in different sectors of the economy differ from each other. Therefore, communication networks of regional power companies, railways, banks, and government bodies have their own characteristics. At a certain stage, when the enterprise becomes sufficiently large and cumbersome, proposals for the creation of joint multiservice networks transmitting multimedia traffic. When the future begins to knock on the door more and more insistently, it is quite appropriate to build multi-service corporate next generation networks . In this case, the enterprise creates a single network designed to transmit heterogeneous traffic. Processing each type of traffic, as one would expect, falls on specialized systems, often traditional computing resources (servers) with appropriate software. In this case, data traffic is confined to servers and databases. Voice traffic will be consolidated into an IP PBX. Video traffic - on video conferencing servers. It's not surprising that specialized application servers will be deployed to handle different types of traffic.

Technologies do not stand still, and creative thought cannot be stopped at all. Time will pass, and traditional ways of organizing corporate communications systems will be replaced by more modern ones, ensuring the deployment of a whole range of new services and new applications. These solutions will pave the way to the hearts of business leaders and IT departments. The victory of new generation multiservice networks will be determined, first of all, by the prospects that they will open up for business. In this case, the cost of the solution will no longer play a decisive role. After all, the advantage of replacing a bicycle with a car was once also questioned. But time has made its own adjustments. Because the new opportunities provided by modern communication systems will be an order of magnitude higher than those offered today.

Who doubts that time is the most powerful innovation factor?

Vladimir SKLYAR

“...A promising direction of development modern systems communications are unified communications..."

A modern corporate communication system today consists of a universal network infrastructure and intelligent services that guarantee the effective integration of communication systems and enterprise business processes. The versatility of the infrastructure allows you to increase the speed of information exchange through the use of the most suitable transmission medium. A promising direction in the development of modern communication systems is unified communications. Within this system, users themselves can choose a convenient mode and format for their interaction at the moment. The system is characterized by a high degree of flexibility and provides users with the ability to switch between communication channels, i.e., a “transparent” transition from one communication application to another directly during the communication process, regardless of the location of the users and the devices used. The unified communications system allows employees to communicate with each other in real time, as well as exchange information through multimedia communication channels, for example, using video telephony systems, audio and web conferencing, IP telephony, voice and email messaging, fax communications, etc. At the same time, employees use all of the above types of communication in a single, unified and natural format, which does not require additional training or development of specialized skills.

“...Give us a connection, and that’s it...”

The very concept of “corporate communication system” has not undergone any significant transformations and, as before, implies a set of technical, organizational, technical and organizational solutions and measures to ensure sustainable management of corporate forces and assets, as well as interaction with other structures through their corporate communication networks and/or public communication networks. Naturally, each word from this definition acquires its own specific content in life for any specific organization. But the essence has remained the same since time immemorial and neatly fits into the slogan “GIVE CONTACT!” For developers and manufacturers of telecommunications equipment, two aspects are important in determining development trends: the direction of technology development and the development path of consumers of these technologies, which, among other things, determines in what volumes and proportions the latest and existing technologies will be in demand by the market. I would like to outline the trends in the development of corporations - consumers of telecommunications technologies - by highlighting several areas for the Ukrainian market. The first group includes corporations that are “young” in age and not burdened with the technological communications equipment of previous generations. They, as a rule, do not have specific requirements for the principles of building a corporate network, but are quite open to the introduction of the latest technologies and, what is not unimportant, are ready for this, including in terms of the level of qualifications of their technical staff. The second direction is represented by corporations that have a certain “life” experience, but which today are experiencing a period of significant reorganization and the introduction of new technologies in their core activities, which is naturally accompanied by a significant modernization of the corporate communication network. In the third direction, corporations are moving that do not undergo any fundamental reorganization of the management system, but within the framework of the existing organizational and technical structure of communications, they are gradually replacing morally and physically outdated equipment with an increase in the level of communications services provided. Here, as a special vector, we can single out corporations whose communication system is strictly integrated into the existing management system, which determines sufficient conservatism in the organizational and technical principles of building networks and regulating the provision of communication services. These are, first of all, the so-called natural monopolies (enterprises of the mining and metallurgical complexes, railway transport, etc.), as well as law enforcement agencies. Traditionally, in such corporations, among the main requirements for communication are its guarantee and reliability. It is with regret that we have to mention the fourth direction, since this is not a direction at all, but a dead end in which there are corporations that objectively feel the need to modernize the communication network, but... I think that the skill of each telecommunications equipment manufacturer lies in correctly determining the direction of development of a particular corporate network and having in its portfolio equipment that can meet the requirements of each potential customer.

«… Corporate system connections like a set of interconnected constituent elements..."

A modern corporate communication system includes the following interconnected components: a single unified network infrastructure (usually based on Ethernet/IP) for transmitting all types of information (data, voice, video); flexible, adaptive, multi-level mechanism for prioritizing various types of data in all parts of the network; an intelligent security system with tools for analyzing transmitted multimedia data at all levels of the network hierarchy with the ability to quickly adapt when new types of threats (attacks) appear; close, “seamless” integration of terminal hardware devices (telephones, video cameras, wireless headsets) with multimedia communication applications at the user’s workplace; the ability for the user to initiate any type of communication (voice, video, short messages, collaboration with applications, etc.) directly from his workplace in any combination, with simple, random access to statistics (history) for each type of communication, the ability working with a single address book of the enterprise; availability of all types of communications in full anywhere in the corporate network and anywhere where there is Internet access; tight, intuitive integration of communication tools with automated systems planning, management, interaction with customers. At the same time, the migration of modern communication systems occurs in the direction of the communication systems described above. The new things that have appeared on the market lately meet this trend (unified communications, the introduction of SIP, the widespread transition to IP).

“...Corporate communication systems are developing towards convergence of services..."

The corporate communication system is one of the main systems that ensures the functionality of the business of any company. It must solve several key tasks, namely: increase the efficiency of employees by optimizing interaction between them and providing effective means of communication; improve the quality of interaction with the company’s clients, ensuring high-quality processing and distribution of external calls; and reduce operating costs through the use of IP solutions, effective controls and minimizing downtime. A modern corporate communication system today is not just a telephone system and a data network. Such a system should be an integrated environment aimed at solving all communication problems of users, regardless of their location (inside or outside the office) and the available means of communication at their disposal. Corporate communications systems are evolving towards the convergence of services and the provision of new communication capabilities that become available to users. These are video conferencing, collaboration on documents, real-time availability indication, etc. As many companies increasingly employ employees working away from offices, the demands on enterprise mobility capabilities are increasing. Communications convergence in action might look like the ability to use all business telephony features (dial an internal office caller by name, call forwarding, conference calls, etc.), available in the office on a desktop device, also with mobile phone outside the office over GSM or Wi Fi network; or access to corporate email and colleagues' availability status both from a web browser and using a communicator device while traveling, and so on. The Internet and distributed corporate networks are today's business environment, so security requirements are of primary importance due to the ever-increasing number of online threats. Reliability, resiliency, and network optimization for reliable operation of business applications are also critical requirements. Alcatel-Lucent this year proposed a new approach to organizing the enterprise communications environment. This approach allows you to select and implement the solutions needed to solve the communication problems of individual employees based on user profiles. Such a profile includes information about the employee’s mobility requirements (whether mobility is required within the office, outside the office, with access to telephony and data services), as well as the degree of collaboration (interaction, teamwork) with colleagues that the user needs. This approach allows you to implement communication solutions on a modular basis and directly evaluate their effectiveness.

“...Employee of a modern corporation must receive all services, no matter where he is..."

The essence of any modern technology is the ability and ability to migrate. This also applies to communication systems. From large, heavy and very expensive hardware with the manufacturer’s oath of “investment protection” and the ability to modernize - to lightweight and flexible solutions. The only thing that has not been established is the approach: many multi-tasking systems under one management and control, or one “multi-tasking combine”. An employee of a modern corporation should receive all services, regardless of where he is located. In other words, the modern corporate communication system is invariant with respect to time and space. And the migration path can be traced by the behavior of communication equipment manufacturers. Who, if not them, keeps their nose to the wind? Even the largest players in the telecommunications business attach great importance not to hardware components (after all, production is now usually located in the countries of Southeast Asia), but to the variety of software applications and the unification of these same hardware products. Surely, the secret dream of manufacturers is to sell licenses to turn a “piece of iron” into a phone, switch, router or computer, thereby relieving the ballast of hardware production. A unified device would be the most acceptable solution, be it a telephone exchange or a telephone set.

“...Flexibly and quickly provide "ever-increasing" business needs of the company..."

Today, scientific and technological progress, especially in the field of IT technologies, is proceeding at an extremely rapid pace. And whatever function we try to designate as an indicator that the communication system in question is modern, how does a new, more modern function or technology. Communication systems are developing very quickly. So I would still be tied to the business needs of the corporation. That is, a communication system can be considered modern if it allows you to flexibly and quickly solve all the “continuously growing” problems of the company’s business. Regarding the directions of migration of corporate communication systems, you won’t get off with just one phrase. It is difficult to answer this question objectively, because the information I have is based on communication with those respected Customers who contact Avaya specifically. And those who come to us are those who need the kind of functionality that Avaya is famous for. But, nevertheless, I will try to highlight some trends... 1. Almost all large corporations want to have not a network of disparate subsystems (what we lovingly call a “zoo”), but a single, geographically distributed telecommunications system. Such a system is easier to monitor, administer, ensure security, license, scale, increase functionality, etc., etc. It is more flexible and allows for quick reconfiguration to suit the company's changing business conditions. Just yesterday we were proud of our unified systems, consisting of only 7 divisions spread throughout Ukraine. And today some of our unified communication systems already number more than 200. Imagine the scale of the problem if, for example, you want to update a system of separate PBXs of similar size. If there are 250 working days in a year, then this is at least a year. In our case (when the system is single), such a procedure will take only a few minutes. 2.Integration of fixed and mobile communications. The pace of scientific and technological progress today can only be compared with the rate of growth in real estate prices. Therefore, more and more companies are allowing their employees to work from home. Constant traffic jams are an additional stimulating factor in this process. Where is the right specialist located? In the office, at home or in a traffic jam. Where to look for it? It’s convenient when “intelligent” technology takes care of this, and not the respected Customer. A single entry/search point is both convenient and cost-effective. 3. Those functions that we proudly called “Operator Center” a year ago are now requested by nine out of ten Customers. Almost all companies strive to please their Clients with a high level of service. 4.Universalization and open standards. IT systems are becoming more and more complex, and the degree of their mutual integration is becoming deeper. It’s convenient when you can use a regular analog phone to read your email and even respond to letters. But for this it is necessary to connect various subsystems (in this case, the PBX and the email server) into a single whole. If each of the subsystems operates according to its own unique protocols, the problem has no solution.

“...Communication as a control system module business processes of the enterprise..."

In my opinion, it is quite difficult to give an unambiguous definition of modern corporate communications, since this concept includes many aspects. From a technological point of view, this is, first of all, a converged voice transmission system. If we take the exact translation from the English word “convergence”, then it means “convergence, convergence” - meaning, many technologies - for their joint and simultaneous use. That is, not the replacement of all previous ones with one, for example VoI P, but the coexistence and joint use by the customer of any available technologies in any combination to achieve one goal - high-quality and reliable communication. From a functionality point of view, it is a flexibly expandable and manageable system that allows you to smoothly increase functionality, introduce new services (for example, conferences) and types of communication (in particular, video). Ideologically, it is a company management tool. The same part of a company’s business processes as, for example, CRM or ERP. From a material point of view, a corporate communications system is a complex of (often) expensive equipment designed to maximize the return on investment made in it. Finally, if we talk about aesthetics, then this is a bunch of telephones on tables that can completely ruin the design of the room. I said “finally,” but this list can be continued indefinitely, because there are many other requirements: for reliability, security/security and others, which have always been there, but in the conditions of modern complex converged networks are becoming more acute. As a manager, I am primarily interested in the possibilities of corporate communications as a module of a certain enterprise business process management system, where the communication system appears on an equal basis with other software and hardware modules. This approach is already clearly visible in the solutions of leading manufacturers, and in particular, it is very clearly reflected, for example, in the CEBP (Communications Enabled Business Processes) concept from Avaya. The point is that previously the communication system was considered either separately from everything else, or as a transport for transmitting information within a corporation. A modern communication system can, receiving information from an enterprise resource planning (ERP) system, automatically make calls, send notifications, hold conferences, etc. It is clear that in such solutions there is a large share of software, and the hardware platform is being standardized and gradually unified.