Olifer computer networks 3rd edition. Olifer V.G., Olifer N.A. Computer networks. Principles, technologies, protocols. Electronic textbook

Hello Khabro residents! We decided to write a review dedicated to the textbook about network technologies:

The fifth edition of one of the best Russian textbooks on network technologies, translated into English, Spanish, Portuguese and Chinese, reflects the changes that have occurred in the field of computer networks over the 6 years that have passed since the preparation of the previous edition: local and global networks have overcome the speed limit at 100 Gbit/s and mastering terabit speeds; increasing the efficiency and flexibility of primary optical networks due to the emergence of reconfigurable add-drop multiplexers (ROADM) and the use of DWDM superchannels operating on the basis of flexible frequency plan; development of virtualization technology network functions and services that led to the spread cloud services; bringing security issues to the forefront.
The publication is intended for students, graduate students and technical specialists who would like to gain basic knowledge about the principles of building computer networks, understand the features of traditional and promising technologies local and wide area networks, explore ways to create and manage large composite networks.

From the authors

This book is the result of the authors' many years of experience teaching networking courses in public universities and various training centers, as well as participation in scientific and technical developments such as the Janet project, associated with the creation of a unifying network of university campuses and research centers in the UK, and the pan-European GEANT2 projects and GEANT3.

The book is based on materials from the courses “Problems of building corporate networks", "Fundamentals of network technologies", "Organization of remote access", "TCP/IP networks", "Strategic planning of enterprise-scale networks" and several others. These materials have been successfully tested in an uncompromising and challenging audience consisting of listeners with significantly different levels of training and range of professional interests. Among them were university students and graduate students, network administrators and integrators, automation managers and educators. Taking into account the specifics of the audience, the lecture courses were structured so that the beginner received a basis for further study, and the specialist systematized and updated his knowledge. This book is written along the same principles - it is a fundamental course in computer networking that combines breadth of coverage of the main areas, problems and technologies of this rapidly developing field of knowledge with a thorough discussion of the details of each technology.

Who is this book for?

The book is intended for undergraduates, graduate students and technical specialists who want to gain basic knowledge about the principles of building computer networks, understand the features of traditional and emerging technologies of local and wide area networks, and learn how to create large composite networks and manage such networks.

The textbook will be useful to beginners in the field of network technologies who have only a general understanding of how networks work from experience with personal computers and the Internet, but would like to gain fundamental knowledge that will allow them to continue studying networks on their own.

The book can help established network specialists get acquainted with technologies that they have not had to deal with in practical work, systematize existing knowledge, become a reference book that allows you to find a description of a specific protocol, frame format, etc. In addition, the book provides the necessary theoretical basis for preparing for certification exams such as Cisco CCNA, CCNP, CCDP and CCIP.

Higher education students educational institutions, studying in the direction of “220000. Informatics and Computer Science" and in the specialties " Computing machines, complexes, systems and networks", "Automated machines, complexes, systems and networks", " Software computer technology and automated systems", can use the book as recommended by the Ministry of Education of the Russian Federation teaching aid.

Chapter 25

Network Management Service

Functions of network management systems

Like any complex technical object, a computer network requires performing various actions to maintain it in working order, analyze and optimize its performance, protect against internal and external threats. Among the variety of means used to achieve these goals, important place occupied by network management services (systems).

A network management system (NMS) is a complex software and hardware complex that monitors network traffic and manages the communications equipment of a large computer network.

Network management systems usually operate in an automated mode, performing the most simple steps automatically and leaving the person to make complex decisions based on the information prepared by the system.
The network management system is designed to solve following groups tasks:

- Network configuration and naming management consists of configuring the parameters of both individual network elements and the network as a whole. For network elements such as routers, multiplexers, etc., configuration consists of assigning network addresses, identifiers (names), geographic location, etc. For the network as a whole, configuration management usually begins with building a network map, that is, with displaying real connections between network elements and connections between them.

- Error processing includes identifying, determining and eliminating the consequences of failures and failures.

- Performance and Reliability Analysis associated with assessment based on accumulated statistical information parameters such as system response time, throughput real or virtual communication channel between two end subscribers of the network, the intensity of traffic in individual segments and channels of the network, as well as the likelihood of data corruption when transmitted through the network. Performance and reliability analysis results allow you to monitor service level agreement(SLA), concluded between the network user and its administrators (or the company selling the services). Without performance and reliability analytics, the public network service provider or department information technologies enterprises will not be able to control, much less provide the required level of service for end users networks.

- Security Management implies control of access to network resources (data and equipment) and maintaining the integrity of data when stored and transmitted through the network. Basic elements security management are user authentication procedures, assignment and verification of access rights to network resources, distribution and support of encryption keys, authority management, etc. Often the functions of this group are not included in network management systems, but are either implemented in the form of special security products, For example firewalls or centralized authorization systems, or are part of operating systems and system applications.

- Network accounting includes recording the time of use of various network resources (devices, channels and transport services) and maintaining billing transactions (payment for resources).

Management systems standards do not distinguish between managed objects representing communications equipment (channels, local network segments, switches and routers, modems and multiplexers) and objects representing computer hardware and software. However, in practice, the division of control systems by type of controlled objects is widespread.

In cases where the managed objects are computers, as well as their system and application software, a special name is often used for the management system - system management system (SMS).

SMS usually automatically collects information about computers installed on the network and creates records in a special database about hardware and software resources. SMS can centrally install and administer applications that run from servers, as well as remotely measure the most important parameters computer, operating system, DBMS (for example, processor or physical memory utilization rate, page fault rate, etc.). SMS allows the administrator to take over remote control of the computer in emulation mode GUI popular operating systems.

Architecture of network management systems
Agent managed object

To solve these problems, it is necessary to be able to control a separate device (object). Typically, each device that requires fairly complex configuration is accompanied by the manufacturer standalone program configuration and management running in a specialized OS environment installed on this device. We will call this software component agent. Agents can be embedded in managed equipment or run on a device connected to the management interface of that device. One agent in general case can control several similar devices.

The agent maintains an interface with the operator/administrator, who sends it requests and commands to perform certain operations.

The agent can perform the following functions:
- store, retrieve and transmit upon external requests information about the technical and configuration parameters of the device, including the device model, number of ports, type of ports, OS type, connections with other devices, etc.;
- perform, store and transmit, upon request from outside, measurements (calculations) of device operating characteristics, such as the number of received packets, the number of discarded packets, the degree of buffer fill, port status (working or non-working);
- change configuration parameters based on commands received from outside.

In the described scheme, the agent plays the role of a server, which is contacted by the client-administrator with requests for the values of characteristics or for setting the configuration parameters of the managed device.

To obtain the required data about an object, as well as to issue control actions on it, the agent must be able to interact with it. The variety of types of managed objects does not allow standardizing the way an agent interacts with an object. This problem is solved by developers when integrating agents into communication equipment or into the operating system. The agent can be equipped with special sensors to obtain information, for example temperature sensors. Agents can differ in different levels of intelligence: from minimal, sufficient only to count frames and packets passing through equipment, to very high, allowing to execute sequences of control commands in emergency situations, build time dependencies, filter emergency messages, etc.

Two-link and three-link control schemes

Among the tasks defined for network management systems, there are relatively rare operations, for example, configuring a particular device, and there are also those that require frequent system intervention (analyzing the performance of each network device, collecting statistics on device loading). In the first case, “manual” control is used, when the administrator sends commands to the agent from his console. It is clear that this option is not at all suitable for global monitoring of all network devices.

Let's first consider the manual option two-link control (Fig. 25.1). As a protocol for interaction between client and server, for example, the remote control protocol can be used. telnet management, the client part of which must be installed on the administrator’s computer, and the server part on the device. The telnet server must also support an interface with the agent, which will provide information about the state of the managed object and the value of its characteristics. On the client side, the telnet protocol may be associated with a graphical user interface program that, for example, displays to the administrator graphically requested characteristic. In general, an administrator can work with multiple agents.

The HTTP web service protocol is often used as a protocol for interaction between the client and server parts.

For tasks requiring frequent control operations separate devices, and also with an increase in the number of controlled devices, the considered scheme can no longer solve the problem. A new intermediate link is introduced into the scheme, called a manager. The manager is designed to automate the operator’s interaction with multiple agents. Shown in Fig. 25.2, the network management service diagram is implemented as three-tier distributed application, in which the functions between the links are distributed as follows.

The first link is the control system client, installed on the operator’s computer, supports user interface with an intermediate server.

The second link is an intermediate server that performs the functions manager, is installed either on the operator’s computer or on a specially dedicated computer. The manager usually interacts with several clients and agents, ensuring dispatch of client requests to servers and processing data received from agents in accordance with the tasks assigned to the management system. To improve reliability and performance, the control system can have multiple managers.

Third link agent, is installed on the managed object or its associated computer.

Interaction between manager, agent and managed object

Let us dwell in more detail on that part of the control system that relates to the interaction of the manager, agent and managed object (Fig. 25.3).

For each managed object in the network, some object model is created. It represents all the characteristics of an object that are needed to control it. For example, a router model typically includes characteristics such as the number of ports, their type, routing table, and the number of frames and link-, network-, and transport-layer protocol packets passing through those ports. Models of network objects are used by the manager as a source of knowledge about what set of characteristics a particular object has.

The object model coincides with the logical schema of the object's database (DB), which stores the values of its characteristics. This database is stored on the device and is constantly updated with the results of characteristics measurements carried out by the agent.

In network management systems built on the basis of the SNMP protocol, such a database is called database control information (Management Information Base, MIB).

The manager does not have direct access to the MIB database; to obtain specific values for the characteristics of an object, he must contact its agent over the network. Thus, the agent is an intermediary between the managed object and the manager. The manager and agent interact using a standard protocol. This protocol allows the manager to request the values of parameters stored in the MIB, and the agent to transmit information on the basis of which the manager should manage the object.

Distinguish in-band management(In-band), when control commands go over the same channel over which user data is transmitted, and out-of-band management(Out-band), that is, carried out outside the user data transmission channel.

In-band control is more cost-effective because it does not require the creation of a separate infrastructure for transmitting control data. However, out-of-band management is more reliable, since the corresponding equipment can perform its functions even when certain network elements fail and the main data transmission channels are unavailable.

The “manager - agent - managed object” scheme allows you to build control systems that are structurally quite complex.

The presence of several managers allows you to distribute the load of processing control data between them, ensuring system scalability. As a rule, two types of connections between managers are used: peer-to-peer (Fig. 25.4) and hierarchical (Fig. 25.5). Each agent shown in the figures manages one or more network elements (Network Element, NE), the parameters of which it places in the corresponding MIB base. Managers retrieve data from the MIB databases of their agents, process

They are stored in their own databases. Operators working at workstations can connect to any of the managers and, using a graphical interface, view data about the managed network, as well as issue some directives to the manager for managing the network or its elements.

When peer-to-peer connections, each manager manages his part of the network based on information received from underlying agents. There is no central manager. Coordination of managers' work is achieved through the exchange of information between managers' databases. Peer-to-peer construction of a control system is today considered ineffective and outdated.

Significantly more flexible hierarchical building connections between managers. Every manager lower level also acts as an agent for the manager top level. Such an agent already works with an enlarged MIB model of its part of the network. This MIB collects exactly the information that a top-level manager needs to manage the network as a whole.

Network management systems based on the SNMP protocol
SNMP protocol

The SNMP (Simple Management Network Protocol) protocol is used as the standard protocol for manager-agent interaction.

The SNMP protocol belongs to the application layer of the TCP/IP stack. To transport its messages, it uses the UDP datagram transport protocol, which is not known to provide reliable delivery. The TCP protocol, which organizes reliable connection-based message transmission, has a significant workload. managed devices, which at the time of the development of the SNMP protocol were not very powerful, so it was decided to abandon the services of the TCP protocol.

SNMP is a request-response protocol, that is, for every request received from the manager, the agent must send a response. A special feature of the protocol is its extreme simplicity - it includes only a few commands.

The GetRequest command is used by the manager to request the agent for the value of a variable by its standard name.
- The GetNextRequest command is used by the manager to retrieve the value of the next object (without specifying its name) when scanning the object table sequentially.
- Using the Response command, the SNMP agent sends the manager a response to the GetRequest or GetNextRrequest command.
- The SetRequest command allows the manager to change the values of any variable or list of variables. The SetRequest command is used to actually control the device. The agent must “understand” the meaning of the values of the variable that is used to control the device, and based on these values, perform the actual control action: disable a port, assign a port to a specific VLAN line, etc. The Set command is also suitable for setting the condition under which SNMP -the agent must send the manager a corresponding message. In this way, the response to events such as agent initialization, agent restart, connection loss, connection restoration, incorrect authentication, and loss of the nearest router can be determined. If any of these events occur, the agent issues an interrupt.
- The Trap command is used by the agent to notify the manager that an exception has occurred.
- The GetBulk command allows the manager to get several variables in one request.
SNMP messages, unlike many other messages communication protocols, do not have headers with fixed fields. Any SNMP message consists of three main parts: the protocol version, the general string, and the data area.

General string(community string) is used to group devices managed by a specific manager. The public string is a kind of password, since in order for devices to communicate using the SNMP protocol, they must have the same value for this identifier (the default string is often “public”). However, this mechanism serves more for “recognition” of partners than for security.

The data area contains the described protocol commands, as well as object names and their values. A data area consists of one or more blocks, each of which can be one of the listed SNMP command types. Each type of command has its own format. For example, the format of the block associated with the GetRequest command includes the following fields:

Request ID;
- error status (yes or not);
- error index (type of error, if any);
- list of SNMP MIB object names included in the request.

MIB Database

The MIB database contains set values various types variables characterizing a specific managed object. In the very first version of the standard (MIB-I), 114 types of variables were proposed to be used to characterize a device. These variables are organized in a tree. From the root there are 8 branches corresponding to the following eight groups of variables:

System- general data about the device (for example, vendor ID, time of last system initialization);
Interfaces- parameters of the device’s network interfaces (for example, their number, types, exchange rates, maximum packet size);
Address Translation Table- description of the correspondence between network and physical addresses (for example, using the ARP protocol);
Internet Protocol- data related to the IP protocol (addresses of IP gateways, hosts, statistics about IP packets);
ICMP- data related to the ICMP protocol;
TCP- data related to the TCP protocol (number of transmitted, received and erroneous TCP messages);
UDP- data related to UDP protocol(number of transmitted, received and erroneous UPD datagrams);
E.G.P.- data related to the EGP protocol (number of messages received with errors and without errors).

Each group of characteristics forms a separate subtree. The following are the variables of the variable subtree Interfaces, used to describe the interface of the managed device:

IfType - the protocol type that the interface supports (this variable accepts the values of all standard protocols link level);
ifMtu - maximum packet size network layer, which can be sent through this interface;
ifSpeed - interface bandwidth in bits per second;
ifPhysAddress - physical address of the port (MAC address);
ifAdminStatus - desired port status (up - ready to transmit packets, down - not ready to transmit packets, testing - is in test mode);
ifOperStatus - the actual current status of the port, has the same values as ifAdminStatus;
ifInOctets - the total number of bytes received by this port, including service ones, since the last initialization of the SNMP agent;
ifInUcastPkts - the number of packets with an individual interface address delivered to the upper-level protocol;
ifInNUcastPkts - the number of packets with a broadcast or multicast interface address delivered to the upper-level protocol;
ifInDiscards - the number of valid packets received by the interface, but not delivered to the upper-level protocol, most likely due to an overflow of the packet buffer or for another reason;
ifInErrors - the number of incoming packets that were not transmitted to the upper-level protocol because errors were detected in them.

In addition to the variables describing statistics on input packets, there is a similar set of variables related to output packets. Even more detailed statistics about network operation can be obtained using the SNMP protocol extension RMON(Remote Network MONitoring - remote network monitoring). Management systems built on the basis of RMON have the same architecture, the elements of which are managers, agents and managed objects. The difference is that SNMP systems collect information only about events occurring on those objects on which agents are installed, while RMON systems also collect information about network traffic. Using the RMON agent built into a communication device, you can conduct a fairly detailed analysis of the operation of a network segment. By collecting information about the most common types of errors in frames, and then obtaining the dependence of the intensity of these errors on time, we can draw some preliminary conclusions about the source of erroneous frames and, on this basis, formulate more subtle conditions for capturing frames with specific features corresponding to the proposed version. All this helps automate troubleshooting in the network.

Mode remote control and telnet protocol

Remote control mode, also called terminal access, involves the user turning his computer into a virtual terminal of another computer, which he gains remote access to.

During the formation of computer networks, that is, in the 70s, supporting such a mode was one of the main functions of the network. X.25 PADs existed precisely to provide remote access to mainframes for users located in other cities and working at simple alphanumeric terminals.

The remote control mode is implemented by a special protocol application level, working on top transport protocols, which connect a remote node to a computer network. Exists a large number of remote control protocols, both standard and proprietary. For IP networks, the oldest protocol of this type is telnet (RFC 854).

The telnet protocol operates in a client-server architecture and provides alphanumeric terminal emulation, limiting the user to command line mode.

When a key is pressed, the corresponding code is intercepted by the telnet client, placed in a TCP message, and sent across the network to the host the user wants to control. When arriving at the destination host, the key pressed code is extracted from the TCP message telnet server and is transmitted operating system node. The OS treats the telnet session as one of the sessions local user. If the OS responds to a key press by displaying the next character on the screen, then for the session remote user this character is also packaged into a TCP message and sent over the network to the remote host. The telnet client extracts the character and displays it in its terminal window, emulating the remote host's terminal.

The telnet protocol was implemented in the Unix environment and along with by email and FTP access to file archives has been a popular Internet service. However, since telnet technology uses passwords to authenticate users, transmitted over the network in plain text, and therefore can be easily intercepted and used, telnet now operates primarily within a single local network, where there is much less opportunity for password interception. For remote management of nodes via the Internet, instead of telnet, it is usually used SSH protocol(Secure SHell), which, like telnet, was originally developed for the Unix OS1. SSH, like telnet, transmits characters typed on the user's terminal to a remote host without interpreting their content. However, SSH has measures to protect the authentication and user data that is transmitted.

Today, the main area of application of telnet is managing not computers, but communication devices: routers, switches and hubs. Thus, it is no longer a user protocol, but an administration protocol, that is, an alternative to SNMP.

Nevertheless, the difference between the telnet and SNMP protocols is fundamental. Telnet requires human participation in the administration process, since, in fact, it only broadcasts the commands that the administrator enters when configuring or monitoring a router or other communication device. The SNMP protocol, on the contrary, is designed for automatic monitoring and management procedures, although it does not exclude the possibility of administrator participation in this process. To eliminate the danger posed by transmitting passwords to open form Through the network, communication devices enhance their security. Typically a multi-level access scheme is used when open password allows read-only basic characteristics device configuration, and access to the configuration change tools requires a different password, which is no longer transmitted in clear text.

conclusions

A network management system is a complex software and hardware system that monitors network traffic and manages the communications equipment of a large computer network.

The most common is a three-tier network management system architecture, consisting of an administrator, a program manager and a software agent built into the managed equipment.

For each managed object in the network, some object model is created. It represents all the characteristics of an object that are needed to control it.

The manager and agent work based on standard MIBs that describe managed objects. communication devices. This database is stored on the device and is constantly updated with the results of the agent's performance measurements.

SNMP is a TCP/IP stack protocol that organizes the interaction between the manager and the agent in a request-response mode.

Remote control mode, also called terminal access mode, involves the user turning his computer into a virtual terminal of another computer, which he can access remotely.

The remote control mode is implemented by a special application-level protocol that runs on top of transport protocols that connect the remote node to the computer network. For IP networks, the oldest protocol of this type is telnet, which provides alphanumeric terminal emulation, limiting the user to command line mode.

Reviewers:
Department of Computer Science, Faculty of Computers and Systems, Moscow State Institute of Radio Engineering, Electronics and Automation (Technical University);
Yu. A. Grigoriev, Doctor of Technical Sciences, Professor of the Department of Information Processing and Control Systems
Moscow State Technical University named after. N. E. Bauman;
B. F. Prizhukov, Ph.D., Deputy Head of the Information Computing Center of JSC Moscow Intercity
and international telephone"

More details about the book can be found at

The new edition of one of the best Russian textbooks on network technologies can be considered an anniversary one. Exactly 10 years have passed since the first publication of the book “Computer Networks. Principles, technologies, protocols." During this time, the book gained wide popularity in Russia and was published in English, Spanish, Portuguese and Chinese, and with each new edition it was significantly updated. This fourth edition was no exception, with many new sections dedicated to the most current areas of network technology.
The publication is intended for undergraduates, graduate students and technical specialists who would like to gain basic knowledge about the principles of building computer networks, understand the features of traditional and advanced technologies of local and global networks, and study ways to create large composite networks and manage such networks.
Recommended by the Ministry of Education and Science of the Russian Federation as a textbook for students of higher educational institutions studying in the field of “Informatics and Computer Science” and in the specialties “Computers, complexes, systems and networks”, “Automated machines, complexes, systems and networks” , “Computer software and automated systems.”

Basics of data networks.
The process of cognition always develops in a spiral. We cannot immediately understand and realize a complex phenomenon, we must consider it from different points of view, as a whole and in parts, in isolation and in interaction with other phenomena, accumulating knowledge gradually, from time to time returning to what is already seemingly understood and with with each new turn penetrating more and more into the essence of the phenomenon. A good approach is to first study the general principles of some field of knowledge and then detailed consideration implementation of these principles in specific methods, technologies or designs.

The first part of the book is the “first round” of studying computer networks. This part, consisting of seven chapters, describes the basic principles and architectural solutions, which underlie all modern network technologies discussed in subsequent parts of the book. Following the process of network convergence, we examined the principles of switching, multiplexing, routing, addressing and network architecture from the most general positions, comparing the principles of organizing computer networks with similar principles of other telecommunication networks - telephone, primary, radio and television.

The part concludes with a chapter devoted to quality of service problems in packet networks. The new role of computer networks as the basis for creating the next generation public networks providing all types information services and carrying data, as well as audio and video traffic, has led to the penetration of quality of service methods into almost all communication technologies. Thus, the concepts of quality of service, which have been considered for quite a long time as a non-trivial direction in the network industry, have become one of the basic principles building computer networks.

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Textbook. - St. Petersburg: Peter, 2001, 672 p.
ISBN: 5-8046-0133-4
The textbook outlines the main sections of discrete mathematics and describes the most important algorithms on discrete data structures. The book is based on material from a lecture course that the author has been giving at St. Petersburg State Technical University for the last decade and a half.
For university students, practicing programmers and everyone who wants to study discrete mathematics.
Content:
General principles construction of computer networks.
From centralized systems to computer networks.
Evolution of computing systems.
Computer networks are a special case of distributed systems.
Basic software and hardware components of the network.
What does the use of networks give to an enterprise?
The main problems of building networks.
Communication between a computer and peripheral devices.
The simplest case of interaction between two computers.
Problems of physical data transmission over communication lines.
Problems of combining several computers.
Ethernet - example standard solution network problems.
Structuring as a means of building large networks.
Network services.
Concept open system and problems of standardization.
Multi-level approach. Protocol. Interface. Protocol stack.
OSI model.
Layers of the OSI model.
The concept of an open system.
Modularity and standardization.
Sources of standards.
Standard communication protocol stacks.
Local and global networks.
Features of local, global and metropolitan networks.
Differences between local networks and global networks.
The trend towards convergence of local and global networks.
Networks of departments, campuses and corporations.
Networks of departments.
Campus networks.
Corporate networks.
Requirements for modern computer networks.
Performance.
Reliability and safety.
Extensibility and scalability.
Transparency.
Support different types traffic.
Controllability.
Compatibility.
Fundamentals of discrete data transfer.
Communication lines.
Types of communication lines.
Communication line equipment.
Characteristics of communication lines.
Cable standards.
Methods for transmitting discrete data at the physical level.
Analog modulation.
Digital coding.
Logic coding.
Discrete modulation of analog signals.
Asynchronous and synchronous transmission.
Data transmission methods of the link layer.
Asynchronous protocols.
Synchronous character-oriented and bit-oriented protocols.
Connection-based and connectionless transmission.
Error detection and correction.
Data compression.
Switching methods.
Channel switching.
Packet switching.
Message switching.
Basic technologies of local networks.
Protocols and standards of local networks.
General characteristics of local network protocols.
IEEE Standards Structure
802.X.
Logical Link Control Layer LLC (802.2) protocol.
Three types of LLC level procedures.
LLC personnel structure. Procedure with restoration of LLC2 frames.
Ethernet technology (802.3).
Access method CSMA/CD.
Maximum Ethernet performance.
Ethernet technology frame formats.
Ethernet Physical Medium Specifications.
Methodology for calculating the configuration of an Ethernet network.
Token Ring technology (802.5).

A token method for accessing a shared environment.
Token Ring frame formats.
Physical layer of Token Ring technology.
FDDI technology.
Main characteristics of the technology.
Features of the FDDI access method.
Fault tolerance of FDDI technology.
Physical layer of FDDI technology.
Comparison of FDDI with Ethernet and Token Ring technologies.
Fast Ethernet and 100VG - AnyLAN as a development of Ethernet technology.
Physical layer of Fast Ethernet technology.
Rules for constructing Fast Ethernet segments when using repeaters.
Features of 100VG-AnyLAN technology.
High-speed Gigabit Ethernet technology.
General characteristics of the standard.
Means of ensuring a network diameter of 200 m on a shared medium.
802.3z physical media specifications.
Gigabit Ethernet over Category 5 twisted pair cable.
Construction of local networks according to physical and data link level standards.
Structured cabling system.
Hierarchy in the cable system.
Selecting the cable type for horizontal subsystems.
Selecting the cable type for vertical subsystems.
Selecting the cable type for the campus subsystem.
Hubs and network adapters.
Network adapters.
Hubs.
Logical network structuring using bridges and switches.
Reasons for the logical structuring of local networks.
Operating principles of bridges.
Local network switches.
Full duplex local network protocols.
Frame flow control during half-duplex operation.
Technical implementation and additional functions of switches.
Features of the technical implementation of switches.
Characteristics that affect switch performance.
Additional functions switches.
Virtual local networks.
Typical schemes for using switches in local networks.
Network layer as a means of building large networks.
Principles of networking based on network level protocols.
Limitations of bridges and switches.
The concept of internetworking.
Routing principles.
Routing protocols.
Router functions.
Implementation of internetworking using TCP/IP.
Addressing in IP networks.
Types of TCP/IP stack addresses.
Classes of IP addresses.
Special IP addresses.
Using masks in IP addressing.
The order of distribution of IP addresses.
Automation of the process of assigning IP addresses.
Mapping IP addresses to local addresses.
Mapping domain names to IP addresses.
IP protocol.
Basic functions of the IP protocol.
IP packet structure.
Routing tables in IP networks.
Routing without using masks.
Routing using masks.
Fragmentation of IP packets.
Protocol for reliable delivery of TCP messages.
Routing protocols in IP networks.
Internal and external Internet routing protocols.
Distance vector protocol RIP.
OSPF link state protocol.
Tools for building composite networks of the Novell stack.
General characteristics of the IPX protocol.
IPX protocol packet format.
IPX protocol routing.
Main characteristics of routers and hubs.
Routers.
Enterprise modular hubs.
Blurring the lines between switches and routers.
Global networks.
Basic concepts and definitions.
Generalized structure and functions of the global network.
Types of global networks.
Global connections based on leased lines.
Analog leased lines.
Digital leased lines.
Link layer protocols for leased lines.
Using leased lines to build a corporate network.
Global communications based on circuit-switched networks.
Analog telephone networks.
Dial-up service digital channels Switched 56.
ISDN - networks with integrated services.
Computer global networks with packet switching.
The principle of packet switching using virtual channel technology.
X.25 networks.
Networks Frame Relay.
ATM technology.
Remote access.
Basic schemes of global connections for remote access.
Access computer - network.
Remote access via intermediate network.
Network analysis and management tools.
Functions and architecture of network management systems.
Functional groups of management tasks.
Multi-level representation of management tasks.
Architectures of network management systems.
Management systems standards.
Standardizable elements of the control system.
Standards for management systems based on the SNMP protocol.
OSI management standards.
Monitoring and analysis of local networks.
Classification of monitoring and analysis tools.
Protocol analyzers.
Network analyzers.
Cable scanners and testers.
Multifunctional portable monitoring devices.
Monitoring local networks based on switches.
Traffic monitoring
Virtual network management
conclusions
Questions and Exercises
Conclusion
Application
Answers on questions
Recommended reading

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12.67 MB
added 04/06/2011

Title: Computer networks. Principles, technologies, protocols (4th edition)
Number: V. G. Olifer, N. A. Olifer
Year: 2010
Genre: book
Format: DjVu
Pages: 943 pp.

Description:
The new edition of one of the best Russian textbooks on network technologies can be considered an anniversary one. It's been exactly 10 years since...

91.42 MB
added 11/14/2011

Textbook - textbook for universities (4th ed.); Peter, 2010 - 943 pp.
Scanned pages + recognized text layer

ISBN: 978-5-49807-389-7

A new edition of one of the best Russian textbooks on network technologies. Exactly 10 years have passed since the first publication of the book "Computer Networks. Principles...

Olifer V.G., Olifer N.A. Computer networks. Principles, technologies, protocols. Electronic textbook

4.65 MB
added 11/04/2009

45.49 MB
added 03/19/2010

St. Petersburg: - Peter, 2010, 916 p. 4th ed.

Name: Computer networks - Principles, technologies, protocols - Textbook.

During the time that has passed since the release of the first two editions, the network world has not stood still, new protocols and types of equipment have appeared and existing ones have been improved. All of these changes have required a radical revision of some sections of the book, although much of it remains devoted to traditional networking principles, fundamental concepts, and basic, established networking technologies. The book is intended for undergraduates, graduate students and technical specialists who would like to gain basic knowledge about the principles of building computer networks, understand the features of traditional and emerging technologies of local and wide area networks, and study ways to create large composite networks and manage such networks.
Recommended by the Ministry of Education of the Russian Federation as a textbook for students of higher educational institutions studying in the field of “Informatics and Computer Science” and in the specialties “Computers, complexes, systems and networks”, “Automated machines, complexes, systems and networks”, “ Software for computer technology and automated systems.”

The following new topics were included in the third edition of the book:
Wireless technologies and networks. The absence of this topic was a rather serious shortcoming of the first and second editions of the book, which has now been eliminated. Viewed as general principles wireless communication, so specific technologies this class, such as IEEE 802.11, Bluetooth, Wireless Local Loop.
The description of TCP/IP technology and related technologies has been significantly expanded: IPSec, IPv6. These changes correspond new role IP in the modern telecommunications world.
The approach to the description of QoS has been changed - now this topic permeates the entire book, so that the general principles of ensuring quality of service in packet networks, described in a separate chapter of the first part, are considered more specifically when studying the main transport technologies, such as switched Ethernet, IP, Frame Relay, ATM and MPLS.
The sections devoted to VPNs have been written again, in more detail, in particular, the rapidly growing popularity is described in detail MPLS technology VPN.
Many examples, drawings and problems have been added. As we can see, the formal content of the textbook has not undergone any fundamental changes. In fact, most of the book has been rewritten. Over the 6 years that have passed since the publication of the first edition of the book, not only computer network technologies have changed, but also the authors’ views on many fundamental problems telecommunications. The result of this rethinking was the third edition of the textbook.
And finally, many minor errors and typos in the text and drawings noticed by readers and the authors themselves were corrected.

Summary
Thanks 20
From the authors 21
From the publisher 26
Part I: Basics of Data Networks
Chapter 1. Evolution of computer networks 28
Chapter 2. General principles of network construction 45
Chapter 3. Packet and circuit switching 79
Chapter 4. Network architecture and standardization 118
Chapter 5. Network Examples 157
Chapter 6. Network characteristics 185
Chapter 7. Methods for ensuring quality of service 214
Part II. Physical Layer Technologies
Chapter 8. Communication lines 256
Chapter 9. Data Encoding and Multiplexing 286
Chapter 10. Wireless transmission data 317
Chapter 11. Primary networks 345
Part III. Local networks
Chapter 12. Ethernet Technology 383
Chapter 13. High Speed Ethernet standard 429
Chapter 14. Local networks based on shared media 449
Chapter 15. Switched Local Area Networks 496
Chapter 16. Smart Features switches 534
Part IV. TCP/IP networks
Chapter 17. Addressing in TCP/IP networks 564
Chapter 18. Internetwork Protocol 598
Chapter 19. Basic TCP/IP Protocols 651
Chapter 20: Additional Features of 701 IP Routers
Part V. Wide Area Network Technologies
Chapter 21. Virtual channels in global networks 741
Chapter 22. IP technology in global networks 782
Chapter 23. Remote access 833
Chapter 24. Securing Network Traffic 872
Conclusion. Looking to the Future 916
Recommended and used literature 919
Alphabetical index 922

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