Structured cabling system

Структурированная кабельная система

Let's say there is some hierarchical cable system of the building or group of premises separated into subsystems. All elements of this KS make themselves the uniform designer who is exploited according to the regulations approved in advance. During creation of such system at the initial stage it is necessary to consider that the executed project should be final and capital, as well as the building. However at permanent changes in a data transmission technology engineering services constantly should affect KS. Besides, the existing system requires the solution of the problems arising often at service as internal cable networks are not replaced, and their service requires presence of specialized personnel. All above-mentioned and many other problems can be solved, using SCS.

The market of SCS in Russia

As well as on all construction market the world financial crisis milno struck the sphere of SCS. Together with reduction of volumes of construction also demand for cable products decreases. Read article"The market of SCS in Russia"

Principles of creation of SCS

• Reliability. In this case operating frequency range during all life is meant to support a system capability.
• Compatibility. If at the beginning of development of SCS producers prepared all system for work only with the exclusive equipment, then in the conditions of emerging market it is important to combine devices and component parts from different producers.
• Universality. In addition, use of channels of one type is necessary for signal transmission from different types of systems – video, voice data streams, other information.
• Flexibility and sufficiency. From SCS also existence of additional alternative channels of communication which will be very useful at expansion of structure in use is required. At the same time the convenience and simplicity of service at making changes in the made configuration are important.

Topology

Market development of SCS till 2013 according to the forecast of the research electronics.ca resource

Any SCS represents a tree structure or topology of "a hierarchical star". Nodes of such original structure are specialized premises which connect among themselves optical or copper cables. For creation of SCS two types of premises – equipment rooms or so-called cross rooms are used. The last rooms represent premises in which the switching equipment is located. Usually they play a role of the distributor and are located in close proximity to a strut. In hardware rooms public network equipment is installed: servers, hubs, automatic telephone exchange, etc. It is remarkable that the equipment room can be connected to the cross room of the building (they are marked with BD in the drawing). So network equipment can be connected without additional distributing to a switching part at once. If the equipment room is separately, then network equipment joins CO located locally or directly sockets of jobs. In an equipment room (they are marked with CD in the drawing) cables of the external trunk which connect to it the cross room of the building meet. Directly the internal trunk lines attaching to it the cross the floor keep within it (they are marked with FD in the drawing). Sockets of jobs are connected already to the cross the floor. It should be noted that a system has only one the cross external trunks. Each building, in turn, locates only one the cross buildings if they are in borders of one floor. The cross the floor can service several adjacent floors if the distance allows. Maybe several cross the floor at one level, then everyone the cross of them contacts directly the cross the building.

Standard SCS

Standard cross room

Now we will consider components of SCS which allow to construct the unrolled system for the multi-storey office building. If to take the international ISO/IEC 11801 option as the standard, then the structured cabling system is based on three following elements:

1. Trunk subsystem of a complex. This part includes main cables of a complex, switching connections and connectors. Actually it is about connection of different buildings among themselves. In this case the fiber optic cable which is capable to guarantee high data transfer rate at the level of over 500 Mbps is applied. Optical fiber provides galvanic isolation of buildings for prevention of electrical breakdown which can arise because of potential difference of grounding. It is more preferable to use the protected multi-conductor cable for more reliable protection against mechanical damages. For today's SCS the fiber optic multimode cable of 50/125 microns which is characterized by expanded bandwidth is represented to the most perspective.

2. Trunk subsystem of the building. A problem of this subsystem is connection among themselves of floors of a complex. Data transmission is performed using the unshielded or protected twisted pair cable UTP STP () and also a multimode optical fiber.

3. Horizontal subsystem. The purpose of this subsystem – ensuring communication between a management subsystem with a workplace subsystem. Actually each telecommunication socket in work area connects to a horizontal distribution node which is located in a special mounting cabinet. Regardless of cable type the maximum length of a separate horizontal line cannot exceed 90 meters. The most range horizontal line can be counted up cable length from the socket to the distribution panel in the most mounting cabinet. This segment is considered the basic line. Total length of cables which perform switching in a horizontal cross should not exceed 6 meters, and cord length from the workstation to the socket is strictly limited no more than 3 meters long. The maximum length of a horizontal cable is calculated depending on a class of the channel and ratios of lengths of normal and flexible cables. The necessity of accounting of a ratio of lengths of different types of lines is caused by the worst characteristics of the soft cable (patch cord). In a case with a horizontal subsystem it is recommended to use the unshielded twisted pair, however also the screened option is sometimes allowed.

There is also the fourth subsystem which it is worth mentioning separately. It is a workplace subsystem. In principle, it is a component of a horizontal subsystem and serves for connection of end users to a local network. International standards set service life mounted by SCS during very long term — 10 years. Nevertheless data transmission technologies change, speeds grow. Therefore from external and vertical subsystems the stock on speed is required. At design installation of sockets "with a stock", their functioning and freedom of physical access to them are natural.

Parts of the SCS organization

Функциональные элементы СКС

As an example we will consider one of rational approaches of creation of a cable system and its advantage. Rational approach design process, constructions and laying of all KS elements taking into account the commonly accepted regulations and standards is considered. It is necessary to begin with the fact that when planning a cable system recognize that in each workplace the socket, two-piece should be provided. The first is expected connection of a telephone point or the fax, and the second – directly for the equipment cable. Active network equipment (the hub or the switch) and also passive the cross (for example, a patch panel) is established in one place – as a rule, in a special wiring closet. That telephone lines were the shortest, the internal automatic telephone exchange is located in close proximity. Following advantages:

• The possibility of increase in number of telephone and also network lines in one workplace without laying of additional cables is provided
• In need of installation of new jobs it is not required to lay additional cable lines. It is possible to connect one more user with the help a patch cords, using already existing socket
• Workflow indoors is practically not broken. When moving users in office it is not necessary to lay new lines as they are already initially set in each workplace

Solutions of this sort, technical tricks – all this is not simple to facilitate an opportunity workflow. It is need of today. Cable systems have property to live much longer, unlike the same computer hardware which changes and upgraded constantly. The cable system on which did not feel sorry for means serves long. It is much cheaper in operation and differs in the increased reliability. Business requires full automation of activity of commercial and accounting departments, an inventory control today. For the greatest efficiency and also competent use of the equipment the local computer network better known as a LAN is created. At standard office one server, workstations, several network printers, faxes and also the internal automatic telephone exchange expected a quantity of subscribers are, as a rule, provided. As Wednesday to data transmission in office LAN the Russian installers often use the unshielded twisted pair of the fifth category. According to the theory, connection of a computer hardware in the single functioning network should not cause difficulties owing to logical simplicity of topological structure like "star". The method considers connection by a radial method of the central device and peripheral elements. As a result, many especially economical companies perform wiring by forces of the employees, often from department of technical support. Of course, such employee (and it is possible, and several people) – the system administrator. But this fact does not assume existence of the necessary knowledge concerning nuances of installation of cable systems. Just because SCS – not their major activity. And case at all not that they are bad specialists as some "heads" think. The typical network of such plan is under construction as follows. In some point of the office space the hub expected a certain number of ports is installed. From it lines to workstations are conducted, and existence of sockets is not obligatory at all. Quite often the wire from the hub "rushes" directly to the net board. The cable or keeps within in a box, or is just connected to a plinth. Also it becomes readily available for legs of chairs, legs of employees, the cleaner...

Telephony and SCS

Naturally, telephone communication is important for office not less than a LAN. Laying of telephone lines is performed as follows. Operators who begin laying of own lines come to office. And the premises begin to become covered by abundance of cords and cables. As a result, for the purpose of economy, telephone lines keep within only those places where precisely there have to be telephone points. Most often laying of telephone lines precedes laying of the most local network. Here also some dirty trick is. People who make the decision on structure of creation of KS, seeing the lines which are already laid by operators, consider absolutely excessive action and absolutely empty costs the organization of a cable system from scratch. According to them, you should not do everything at first – phones already work. If the cable system is under construction thus, at increase in number of jobs (if business extends, and will be) net surfers will have questions of the KS organization again. And in most cases it is necessary to begin all over again. � do not save a practical advice which specialists usually give on a cable system. It is better to be left without several computers or to select weaker configuration. Replacement of the machine park will cost cheaper and will not be blow for the developed production structure which can be total replacement of a cable system.

See Also

SCS: Standards

Fiber optic communication

Links

Standards of telecommunication infrastructure of commercial buildings