Tamer Bani Amer

Faculty of computer science and technology (CST)

Department of automated control systems

Speciality "management information systems and technology"

Information systems build cross-checking tests for faults

Scientific adviser: Ph.D., Professor Skobtsov YA

Abstract

Содержание

• Introduction
• 1. The concept of structured cabling system
• 2. Testing of channels and permanent links SCS
• 3. Basic loop testing of cable systems
• 4. Principles of testing of cable systems
• 5. Generation of tests for fault-induced delay
• 6. Selecting the set of critical paths
• 7. A genetic algorithm for generating test
• 8. conclusion
• 9. References

  Introduction

  Virtually all modern information systems and technology in some way connected with the need to exchange and use of various types of communication channels. Immediately channels for transmitting and receiving information based on cable systems must have strict hierarchical structure. At present, three regulations and standards, which describe the concept, purpose, principles and requirements for cable systems, which are called structured. Any serious and advanced structured cabling system (SCS) in preparation for operation should be tested with special equipment for the detection of certain defects and for compliance with the specified characteristics that are defined in advance. This final phase of construction SCS is of fundamental importance. From the results depends on both the quality and durability of the installed system as a whole, and the speed and mobility of the information transfer between the terminal equipment and connected users.

  Testing of modern computer systems requires an analysis of not only classical stuck-at faults, but also more complex models that take into account the temporal characteristics of the circuit. This is typical for deep submicron design. These include "cross fault» (cross talk faults), which usually are two major types of crosstalk:

  1) "crosstalk" induced pulses.

  2) "crosstalk" induced delay.

  1. The concept of structured cabling system

  Structured cabling - is a universal cabling system of the building, group of buildings for use sufficiently long period of time without a restructuring. Versatility SCS involves the use of it for various systems:

  1. computer network.

  2. telephone network.

  3. security system.

  4. fire alarm.

  This cable system is independent of the terminal equipment, allowing a flexible communications infrastructure company. Redundancy involves providing new jobs without laying additional cable lines, for which the SCS must be built with a reserve. Guaranteed time - about 10-15 years, which includes the concept of long-term use without restructuring.
  c In fact, a structured cabling system - a set of passive communication equipment:

  1. Cable - This component is used as a communication media SCS. Cable to distinguish shielded and unshielded.

  2. socket - this part is used as an entry point in the cable network of the building.

  3. patch panels - are used for the administration of cable systems in the switching centers and floors of the building as a whole

  4. patch cords - are used to connect the office equipment in the cable network of the building, the organization structure of the cable system in the switching center.

  To facilitate the design and future maintenance of cable systems have been developed international and European standards for structured cabling system (SCS)

  1. International Standard ISO / IEC 11801 Generic Cabling for Customer Premises.

  2. European standard EN 50173 Information Technology Generic Cabling Systems.

  3. American Standard ANSI / TIA / EIA 568-A/568-V Commercial Building Telecommunication Cabling Standard.

  The standards are meant to serve the public interest by eliminating misunderstandings between manufacturers and consumers, enabling interchangeability and universal quality products, along with its affordability and competent use. Standards telecommunications infrastructure should provide work of different types of equipment from any manufacturer, the creation of cable systems during the construction of buildings and their continuous operation.

  2. Testing of channels and permanent links SCS

  The complex individual measurements of electrical and optical components of SCS, as well as lines mounted on their base is designed to determine the status of SCS, prevention of damage accumulation of statistical data used in the development of measures to improve the reliability of communication, and, finally, is mandatory before entering the SCS-up . Measurements are made in the following cases:

  1. during the execution of an input control of individual components before starting work on their installation.

  2. during acceptance testing of SCS.

  3. during the operation of cable systems in the performance of preventive, emergency and audit.

  

  Figure 1 - Structure of the types of measurements in ACS

  Transmission characteristics of paths that are created by SCS to transmit signals of various engineering systems are discussed and evaluated in the standard ISO / IEC 11801:2002 (E) using the concepts channel (English channel) and fixed line (born permanent link). A channel refers to the transmission path for signals from one SDR to the other active components. Sami plug on the cable ends are not part of the channel because of their impact on the system as a whole is taken into account by developers of active equipment. Under the fixed line is the piece signal path for SCS, which includes a stationary cable and connectors on the ends.

  3. Basic loop testing of cable systems

  Attenuation (Attenuation) - loss of signal power. This ratio of the signal power at the transmitter output to the signal power at the receiver input, expressed in decibels (dB). The smaller the attenuation, the greater the signal at the receiver, the better the bond.

  A = lg (P1 / P2),

  where P1 - the signal power at the transmitter output, P2 - the signal power at the receiver input.

  

  Figure 2 - The distribution of the signal power

  A = 10 lg (P1 / P2) = 10 lg (U1 I1 / U2 I2) = 10 lg (U1 * (U1 / R1) / U2 * (U2 / R2)), accepts R1 = R2, thus, A = 10 lg (U12 / U22) = 20 lg (U1 / U2).

  

  Figure 3 - The dependence of the attenuation of the signal frequency

  Testing is performed for the entire range of operating frequencies. Evaluation result for

  each pair is derived based on the worst-case outcome. Fading channel and the base

  ine is the sum of the attenuation of all their constituent elements: horizontal cable,

  terminals and patch cords and connectors. Maximum attenuation may be expressed as follows:

  All researches were held with the help of CAD Xilinx ISE 13.1 for the family of FPGA Xilinx Spartan-3, namely for the chip XC3S200. Results for cumulative hardware amount for five variants of implementation are graphically shown on fig. 3.

  A = ? + Arazema AHDMI to 100m * (Lcable + 1,2 * ? Lshnurov) / 100.

  where ? Arazema - the sum of the maximum allowable attenuation of all the connectors (in the channel can have up to four sockets in the base lines are always two connectors); AHDMI at 100m - the maximum attenuation of the horizontal cable to a length of 100 m; Lcable - the actual length of the horizontal cable channel or baseline; ? Lshnurov - actual sum of the lengths of cord channel or baseline.

  4. Principles of testing of cable systems

  End users and network designers are constantly plan higher data rate capabilities transmit more data, and the ability of the network to a flexible and easy reconfiguration. It is believed that about 20% of high-speed networks do not provide the performance possible, which is the result of poor quality of the cable systems. This is especially evident in high-speed systems, which include Fast Ethernet, switched LAN, Gigabit Ethernet. However, some low-speed system (Ethernet, Token Ring) can suitably operate even illiterate installation.

  5. Generation of tests for fault-induced delay.

  Generation of test generation for these failures is different from the construction of tests for the failures of the signal propagation delay is despite the fact that it is also based on the use of pairs of test suites. When constructing a checking sequence for such a failure is necessary to: 1) find the input sets that cause the necessary shift signals on the line aggressor 2) to find the input sets that provide the necessary modification of the signal on the line, 'victim' and the spread of the delay arose from a victim to one of the external inputs. The problem of constructing a test pair of input vectors for a given pair of lines scheme "victim-aggressor" was considered in previous work. Here we consider the problem of test generation for multiple faults delays induced by different lines aggressors. In this formulation of the problem of the victim line are included in some way connecting external input with an external output of the circuit. The set of lines formed by those of the aggressor line circuits that can affect the line of victims and thus cause a delay in the signal propagation in the specified path. In solving this problem to be solved, at least three sub-tasks:

  1) the choice of the set of critical paths, forming a line-sacrifice.

  2) selecting a plurality of lines of the aggressor for a given critical path.

  3) the construction of a pair of input test patterns that check-induced delay for a given path and multiple lines of the aggressor.

  6. Selecting the set of critical paths

  The number of possible cross-faults - lp victim-aggressor for the real circuit is very large. But most of these faults do not make sense or is not possible to test. Therefore, the first step is usually abbreviated set of fault-induced delay based on a static timing analysis scheme. In this case, perform the following steps:

  1. For each line, the scheme must be to find a "time window", which is determined by the earliest and latest possible time in the signal.

  2. Of the maximum values ??of later times the signal sequence to find the longest (critical) path in the circuit. The lines included in this way form a potential "victim" for cross faults.

  3. The time window for each line - the victim should be compared with the time window of the potential lines of the aggressor. If these windows are disjoint, then the pair victim-aggressor entered into a set of cross-faults.

  7. Selecting the set of critical paths

  Genetic algorithms are widely used in the construction of proveryayuschihtestov for stuck-at faults, more complex models, for example, the signal propagation delay because of the simplicity, stability, and efficiency. In our opinion, their use in the construction of more complex test patterns for faults even more justified, since in this case it is difficult to use deterministic techniques. Clearly, for cross-checking test failures of the induced delay should consist of pairs of input vectors, ensuring the conditions mentioned above. Obviously, it is desirable to find a pair of sets with a maximum delay that test target fault. It is clear that as individuals GA is advisable to use a pair of input vectors, a lot of which is population. As a fitness function is easier to use the number of tested faults that can be obtained using fault simulation.

  8. conclusion

  The measurements are performed in the SCS at all stages of the construction and operation of cable systems and are essential to the operation and quick recovery channels and paths in emergency situations. It is shown that the use of GA in conjunction with the logical time analysis and simulation can effectively solve the problem of constructing tests for fault-induced.

  

  Figure 1 - Structure of the types of measurements in ACS

  9. References

  1. Semenov, AB, SK Strizhakov, Suncheley IR Structured cabling systems. M. IT Co., DMK Press, 2004. 640.

  2. Samara PA Basics of structured cabling systems. M. IT Co., DMK Press, 2005. 216.

  3.http://www.adp.ru/passive/teh_doc/for_test.htm.

  4.http://www.cnts-net.ru/stati/statia40.dhtml.

  5.Yu.A.Skobtsov. Fundamentals of evolutionary computation. Study posobie.-Donetsk: Donetsk National Technical University, 2008.-326s.

  6.Yu.A.Skobtsov, V.Yu.Skobtsov. Logical modeling and testing of digital ustroystv.-Donetsk: Applied Mathematics and Mechanics of NASU, Donetsk National Technical University, 2005.-436c.

  7.E.Alba, M.Tomassini. Parallelism and evolutionary algorithms IEEE trans. On evolutionary computation.-2002.-vol.6, N5.-P.443-462.