During the crisis, customers began to think about expediency costs and ask the question: “Is it worth installing SCS category 6, category 6A, category 7 and 7A? Is there any undeniable practical advantage of using these categories over SCS category 5e, and how can this advantage be really used?
Let's deal with this issue and dispel some myths.
The cable line, built on the components of category 6A, allows you to organize the transfer of information at a speed of 10 Gigabit / s, using 10 Gigabit Ethernet (10GbE) technology, at a distance of up to 100 meters. In the future, it will be possible to raise the transfer rate to 40 Gigabit/sec, although equipment with copper ports at such a speed will not appear soon and the port will cost the customer a round sum.
On a twisted-pair SCS cable of category 6, transmission at 10 Gigabit / s can be carried out at a distance of 30-55 meters. Up to 30 meters should work if the designers and installer did everything right. Within 30–55 meters, 10 Gigabits / sec can work, or maybe not - who and how lucky. Over 55 meters most likely will not work.
Category 5e twisted-pair cable allows you to easily transfer data at a speed of 1 Gigabit / s in a channel up to 100 meters long.
Now think about this...
And why does a workstation need a data transfer rate of 10 Gigabit / s?
Modern desk-top computers have a PCI bus, the bandwidth of which is limited, and a shared PCI bus with arbitration access ... That is, the bus bandwidth is shared between the processor, RAM, internal and external devices. The high-performance PCI-X bus (64bit, clocked at 133MHz) has a bandwidth of just 1Gbps.
Of course, the development of technology and technology does not stand still in the field of tires. For example, a PCI-Express bus up to 16 Gigabit/s has been developed, and the InfiniBand bus has solutions for 40 Gigabit/s. But these tires are too expensive to put on office computers. They are used for data exchange between blade servers, between high-performance network devices, data storage systems (DSS), as well as for interconnecting computing nodes as part of computing systems and supercomputers.
And the most interesting thing is that InfiniBand cables are different from standard SCS cables. That is, you will need InfiniBand cords that differ from standard cables.
But even if there will be a 10 Gigabit bus on workstations in the foreseeable future, then how will we load it and what applications will we use?
The use of category 6A is justified only for solving narrow and specific tasks. For example, it is possible to use category 6A in the data center (data processing centers, data center). There, such solutions can be justified through the use of clustering, consolidation, and virtualization technologies, which will entail aggregation and an increase in traffic between network devices, servers, and data storage systems (SHD), which means there will be a need for 10Gbps and possibly higher.
By the way, if it is higher, then it is far from a fact that category 6A can cope with this task.
If you mount the data center with an eye to the future, then it makes sense to use optical cables in the data center. The power consumption of ports of active equipment with optics is somewhat much lower than that of copper, and the border bandwidth is higher at fiber optic communication lines. And since the power consumption of boards with optical ports is lower, then less heat will be generated in the data center. Since the number of ports in the data center is large, the reduction in electricity consumption per year will be significant, which means investments in optics will be distributed over a longer period and the total cost of ownership (TCO) of the cable network on optics for the data center will cost less than on the cable system with twisted pair cable category 6A. Yes and with fiber optic communication lines (FOCL), there are no problems with pickups and radiation to neighboring cables, equipment, and the environment.
Some computer graphics firms may require 10 Gb/s transmission in the future. But these are very specific tasks, which means they require a different approach to building SCS, it is better in this case to lay optics on such workplaces.
Within 15-25 years, there may be a need for speeds of 10 Gigabit and higher in some large SCS in the backbone. But you need to understand that the length of the trunk, built on a twisted pair, is limited to 100 meters, and again, the trunk on copper is inferior to optics in terms of throughput. Therefore, it is better to immediately build a trunk on optics, which by the way will give us another advantage over twisted pair - complete galvanic isolation.
In order to somehow draw attention to category 7 and category 7A wiring, manufacturers are trying to promote cabling sharing technology. Cabling sharing technology is the use of several twisted pairs of one cable for several applications at once. Something that was once very popular in Russia in the early stages of using category 5 and something that the market has abandoned. Manufacturers say that this technology can be saved, that the total cost of ownership is cheaper. Consumer fraud! All TCO calculations are based on the fact that category 5e wiring will be changed after 5 years. And wiring to category 7A in 15-25 years. So, if you don’t change the wiring in 15 years, then TCO for category 5E will be much better. So it's just a mathematical trick. You won't be able to save on category 7 and category 7A!!!
Yes, and using cabling sharing technology, we reduce the coverage density of the working area, which leads to the use of long and expensive cords. And you also have to use specialized cords with plugs that differ from standard cords with RJ45 plugs. You can no longer connect ordinary cords to a category 7A outlet ... I'm not talking about the prices for sockets, patch panels (patch panels), cords (patch cords) and category 7 and 7A cables.
And most importantly, where are the tasks for category 7A?
Manufacturers will advise 7A for TV, but 5Mbps is enough for a TV channel. Well, let's say that in the future it became 10Mbps per channel, so these are 100 channels on 1Gigabit - is this not enough?
You ask, why there are no advantages at all for categories 6A and 7A?
There is one indisputable advantage of category 6A and category 7A cables. The conductor core of a category 6A and 7A cable is thicker than that of a category 5e cable conductor. A thicker conductor can transfer more electrical power.
It is possible that in the future it will be possible to power the "thin client" over a twisted pair cable. That is, instead of a full-fledged workstation, a box (KVM switch) is installed at the workplace, a keyboard, mouse and monitor are connected to it. KVM switch is already there, but so far the monitors are powered by electrical wiring, and not by twisted pair. Since monitors consume a lot of power and the twisted pair cable simply cannot withstand such a load, the twisted pair jacket will collapse. However, the development of monitors with low consumption is underway, the topic is relevant and in 10 years they may appear on the market at affordable prices.
Twisted-pair power is now being supplied using Power to Ethernet (PoE) switches. But this technology can be used to connect a small number of devices and the power supply over twisted pairs is still very small.
There is one more nuance, cable manufacturers are doing their best to reduce the cost of the cable and the size of the conductor. Therefore, not all category 6A cables will have a thicker conductor, so in 5 years this advantage may not be available for category 6A twisted-pair cables.
What conclusions can be drawn...
Installing category 6 SCS practically makes no sense - money thrown to the wind - I apologize for being so categorical, but it's a fact. Well, if only in a small data center, where the distance is no more than 30 meters.
In a data center, it makes sense to use category 6A, but with this decision, everything must be carefully weighed and it may be better to use category 5E twisted pairs + optical cables.
In a trunk up to 100 meters, it makes sense to lay part of the cable lines on a twisted pair of category 6A.
If a customer in an office building really wants to bet on the future and spend money on SCS category 6A or category 7A, then one cable line can be laid to the workplace of category 6A and the rest of the twisted pairs can be used category 5e.
But it is better to spend money on something really worthwhile and useful!!!
P.S. By the way, only a few structured cabling installers can implement a project in categories 6A and 7A. I know several projects where SCS installers could not certify a structured cabling system, not only for category 6A, but even for category 6
Any SCS includes tens of thousands of different components. The construction of local networks and structured systems is complicated by the huge number of individual elements and devices on the basis of which they are created. To prevent system management from turning into chaos, visual and unique marking of individual groups of components is used.
It is difficult to accurately calculate the damage to the company from downtime during testing and repair of SCS, when the engineer "blindly" tries to find a damaged cable. The installation of SCS and LAN can be significantly improved with a clear segmentation and separation of all used elements and parts.
To simplify orientation in the cable industry, an international system of marking individual parts of the cable network is used, which is an "international language" that allows you to quickly navigate in a structured cable network
General requirements for marking SCS elements are formulated in the current TIA / EIA-606 standard, which describes in detail the groups of network components accepted for indexing: cables, cross equipment, cords and sockets, permanent connectors, trays, boxes and grounding elements.According to the standard, the marking component must comply with the requirements of the UL969 test, namely, it must have a field for applying inscriptions of a certain length and color. Marked components can be of various types and sizes, have high mechanical strength and resistance to environmental influences. The classification of the used cable network marking elements is quite simple. Marked cables installed at the stage of SCS creation are called technological elements.
Markers used already during the operation of the cable network are called finishing. The lack of final marking makes the network management process difficult, so the cable system is not put into operation without the marking and identification process. There are regular marking elements that are included in the delivery of many SCS solutions, for example, panels or sockets.
In modern structured cabling networks, various types of additional tags are widely used, which are produced by specialized companies. Additional tags are distinguished by a variety of colors and good workmanship, which allows you to identify individual links and functional blocks of the enterprise cable system.
The most popular and widespread element of labeling today are adhesive labels, which are used as elements of technological and finishing labeling. Labels are used to identify various components of the SCS: cable and switching equipment, boxes, cabinets, ground plates.
SCS structure
Structured Cabling System (
SCS) should consist of any or all of the following subsystems:
These subsystems include the following functional elements:
- Main Distribution Point (GRP)
- Territory backbone cable
- Distribution Point Buildings (RPZ)
- Main building cable
- Floor Distribution Point (RPP)
- Horizontal cable
- Transition point (TP)
- Telecommunication Connector (TP)
Horizontal subsystem
The horizontal subsystem is the part of the telecommunications cabling system that runs between the telecommunications socket/connector in the workplace and the horizontal distribution box in the telecommunications closet. It consists of horizontal cables and that part of the horizontal distribution box in the telecommunication cabinet that serves the horizontal cable. Each floor of the building is recommended to be served by its own Horizontal Subsystem.
All horizontal cables, regardless of the type of transmission medium, should not exceed 90 m in the section from the telecommunications outlet at the workplace to the horizontal cross. At least two horizontal cables must be laid for each workplace.
For voice and data applications, four-pair UTP/ScTP and fiber optic cables must be run in a star topology from the telecommunications closet on each floor to each individual data outlet. All cable paths must be agreed with the customer before cable laying.
Each segment of the UTP / ScTP cable between the horizontal part of the cross-country in the telecommunication closet and the information outlet must not contain sleeves.
Backbone subsystem
The cable route within the building that connects the cabinet to the cabinet or to the equipment room is called the Backbone subsystem of the building, connecting the main cross-section in the equipment room with intermediate cross-sections (IC) and with horizontal cross-sections in telecommunication cabinets (TC). It consists of a medium in which information is transmitted along the highway between these points, and the corresponding switching equipment that terminates this type of medium.
The backbone subsystem should include a cable installed vertically between storey telecommunication cabinets, a main or intermediate cross-section in a multi-storey building, as well as a cable installed horizontally between telecommunication cabinets, a main or intermediate cross-section in an extended one-story building.
All vehicles must have an adequate cross-sectional area of the trunk route available or available for reuse so that no additional routes need to be created. All trails, if intended for use in telecommunication systems, must have fire plugs, whether the trails are used or not.
Backbone cables should be run topologically in a star pattern, starting at the main distribution frame and running to each telecommunications closet. There may be an intermediate cross between the main and horizontal crosses. Such a system is called a hierarchical star topology.
All telecommunications cabling systems and equipment must be grounded in accordance with relevant codes and regulations.
Highways between buildings
When the distribution system spans more than one building, the components that provide communication between buildings constitute the Backbone subsystem between buildings. This subsystem includes the medium through which trunk signals are transmitted, appropriate switching equipment designed to terminate this type of medium, and electrical protection devices to suppress dangerous voltages when the medium is exposed to lightning and / or high voltage electricity, the peaks of which can penetrate the cable inside the building. This is typically a layer 1 backbone cable running from the main distribution box in the control room of the central building to the intermediate distribution box in the control room of the field building.
The trunk subsystem should include cable laid between buildings, in a tunnel, buried directly in the ground, or in any combination of these methods, and passing from the main distribution block to the intermediate distribution block in a system consisting of several buildings. Backbone cables must be installed in a star topology, starting from the main cross-connect to each telecommunications closet in the field building. All cables between buildings must be installed in accordance with relevant regulations.
Workplace subsystem
This subsystem connects the information socket (telecommunication socket) and the active device (computer/telephone). The subsystem defines the requirements for hardware cords and telecommunications sockets at the user's workplace.
Telecommunication connectors are located on the wall, on the floor or in any other area of the workplace. It all depends on the design of the building. When designing a cabling system, telecommunications connectors should be placed in easily accessible places. The high density of the connectors increases the flexibility of the system in relation to changes. In many countries, connectors are installed on the basis of: two connectors for a minimum of 6 square meters. m. and a maximum of 10 sq. m. m. of working area. Connectors can be installed both separately and in a group, but each workplace must be equipped with at least two connectors.
Each telecommunication socket must be marked with a permanent, highly visible label for the user. Attention should be paid to the marking of each duplex pair: all marking changes must be recorded in the documentation.
Placement of a control room or telecommunications cabinet
The control room subsystem consists of electronic communication equipment for collective (general) use, located in the control room or in a telecommunications cabinet, and the transmission medium necessary for connection to distribution equipment serving the horizontal or backbone subsystems.
Telecommunication cabinets must provide all the necessary conditions (space, power, environmental conditions, etc.) for passive elements and active equipment installed in them. Each cabinet must have direct access to the main cables.
Grounding of telecommunications equipment must be carried out in accordance with local and national regulations.
The equipment includes cross-connect fittings, patch panels and racks, active telecommunications equipment, as well as fixtures and devices for testing. It is also necessary to provide a grounding trunk based on a connecting conductor to ensure a direct connection between the control room and telecommunications cabinets. These elements are part of the grounding infrastructure (a system of telecommunications routes and rooms in the building structure) and are independent of equipment or cabling. The equipment room must not be used by other building services that may directly or indirectly interfere with the functioning of the telecommunications system.
| Subsystem | Signal carrier type | Recommended use |
| Horizontal cables | Voice, data | |
| Optical fiber | If needed (1) | |
| Trunk cables | Shielded or unshielded twisted pair | Voice and low-speed data transmission medium |
| Optical fiber | High speed data transmission medium | |
| Trunk cables of the territory | Optical fiber | For most applications. The use of optical fiber solves many of the problems associated with sources of interference. |
| Shielded or unshielded twisted pair | If needed (2) |
(1 ) Under certain conditions (safety considerations, environmental conditions, etc.) the use of optical fiber for horizontal cables may be considered
(2 ) UTP or FP can be used by the backbone subsystem of the territory, if the distance allows and at the same time, the high bandwidth inherent in optical cables is not required.
* Price in terms of one SCS line.
SCS - the basis of a computer local area network (LAN)
The work of the organization requires a local network that combines computers, telephones, peripheral equipment. You can do without a computer network. It’s just inconvenient to exchange files using floppy disks, line up near the printer, and access the Internet through one computer. The solution is technology, abbreviated as SCS.
A structured cabling system is a universal telecommunications infrastructure of a building or a complex of buildings that provides the transmission of all types of signals, including voice, information, and video. SCS can be installed before users' requirements, data rate, type of network protocols become known.
SCS forms the basis of a computer network integrated with the telephone network. The set of telecommunications equipment of a building / campus, connected using a structured cabling system, is called a local area network.
SCS or computer plus telephone network
Structured cabling systems provide a long service life, combining ease of use, data transmission quality, reliability. The introduction of SCS creates the basis for increasing the efficiency of the organization, reducing operating costs, improving interaction within the company, and ensuring the quality of customer service.
A structured cabling system is built in such a way that each interface (connection point) provides access to all network resources. At the same time, two lines are sufficient at the workplace. One line is a computer line, the second is a telephone line. The lines are interchangeable. Cables connect telecommunication sockets of workplaces with ports of distribution points. Distribution points are connected by trunk lines according to the "hierarchical star" topology.
SCS is an integrated system. Let's compare SCS with the outdated "computer plus telephone network" model. A number of advantages are obvious.
- integrated local network allows you to transmit different types of signals;
- SCS ensures the operation of several generations of computer networks;
- SCS interfaces allow you to connect any equipment of local networks and voice applications;
- SCS implements a wide range of data transfer rates from 100 Kbps voice applications to 10 Gbps data applications;
- administration of SCS reduces the labor costs of maintaining a local network due to ease of operation;
- a computer network allows the simultaneous use of different types of network protocols;
- standardization plus competition in the SCS market provide a reduction in the prices of components;
- the local network allows you to realize the freedom of movement of users without changing personal data (addresses, phone numbers, passwords, access rights, classes of service);
- SCS administration ensures the transparency of the computer and telephone network - all SCS interfaces are marked and documented. The work of the organization does not depend on the employee-monopoly of telephone network connections.
A reliable and durable structured cabling system is the foundation of a local area network. However, every merit has a downside. SCS standards recommend the redundancy of the quantitative parameters of the system, which entails significant one-time costs. On the other hand, you can forget about the nightmare of permanently repairing an existing office in order to build up a computer network to meet current needs.
SCS standards
SCS subsystems
The ISO/IEC 11801 standard divides the structured cabling system into three subsystems:
- the main subsystem of the complex of buildings;
- the main subsystem of the building;
- horizontal subsystem.
SCS backbone subsystem and telephone network
The backbone subsystem of the building complex connects the cable systems of the buildings. The backbone subsystem of the building connects the distribution points of the floors.
The backbone subsystem includes the information and speech subsystems of the SCS. The main transmission medium of the information subsystem is optical fiber (single-mode or multi-mode), supplemented by symmetrical four-pair cables. If the length of the main line does not exceed 90 meters, balanced cables of category 5 and above are used. At longer lengths, for information applications, that is, a computer network, it is required to lay a fiber optic cable.
Building trunk voice applications operate over multi-pair cables. Speech applications that create a telephone network belong to the lower classes of SCS. This allows you to increase the length of the lines of the backbone subsystem, created by multi-pair cables, up to two or three kilometers.
SCS horizontal subsystem and computer network
The horizontal SCS subsystem includes distribution panels, switching cables of floor distribution points, horizontal cables, consolidation points, telecommunication connectors. The horizontal subsystem provides a local network for subscribers and provides access to backbone resources. The transmission medium of the horizontal subsystem is balanced cables not lower than category 5. The 2007 SCS standards provide for the choice of SCS for data centers not lower than category 6. For information technology (computer plus telephone network) of private homes, new standards recommend using category 6 / 7. Transmission medium broadcast communication technologies (abbreviated VKT: television, radio) of private houses / apartments - symmetrical protected cables with a frequency band of 1 GHz, plus coaxial cables up to 3 GHz. Fiber optics are also allowed.
The horizontal subsystem of the SCS is dominated by a computer network. This implies the restriction of the maximum length of the channel - 100 meters, regardless of the type of medium. To extend the service life without modifications, the horizontal SCS subsystem must provide redundancy, a reserve of parameters.
Workspace in the structure of the SCS horizontal subsystem
SCS work area - premises (part of premises) where users work with terminal (telecommunication, information, voice) equipment.
Telecommunication grounding buses (TShZ) are installed in each distribution point near cabinets / racks. Distribution point busbars are connected by grounding lines to the main telecommunications grounding busbar (GTShZ) installed next to the electrical grounding terminal. Modern standards recommend increasing the cross-sectional area of the conductor of the grounding line with an increase in the length of the line. The maximum recommended cross section can be 3/0 AWG or 90 mm2. Line branches are performed by isothermal welding or permanent connection.
Often one has to deal with the absence or improper execution of grounding systems in old buildings. The design of a telecommunications grounding system does not require the elimination of electrical grounding deficiencies. When earthing equipotentiality is not ensured, the principle of "effective shielding" is implemented.
Power supply system
In most cases, for the operation of a computer network, it is necessary to provide power to devices connected to telecommunications connectors. Power sockets are installed at each workplace. Some sockets are used to connect computers and office equipment, others - household electrical appliances. Such separation of systems allows organizing a centralized guaranteed power supply.
It is known that the laying of power cables parallel to information ones worsens the quality of data transmission over low-current lines, which can cause failures of local networks. To reduce this influence, it is necessary to maintain the minimum allowable parallel laying distances, depending on the voltage and load power. Installation of power and low-current networks by one contractor allows solving the problem of electromagnetic compatibility, reducing investment costs.
Socket installation options
Power and telecommunication sockets can be installed in boxes, overhead sockets, walls, telecommunication columns, floor hatches.
The photographs show options for placing telecommunication connectors (TR) with power socket blocks. The most common option for creating cable channels is plastic boxes. Walls, office furniture, even ceilings are used to fix boxes. Boxes with a height of more than 80 mm are convenient for placing sockets. Narrow boxes are complemented by wall sockets.
Socket groups can be marked with markings or insert colors. For example, red inserts for powering a computer network, white ones for connecting household electrical appliances.
Telecommunication columns, floor racks, floor hatches are used less often. The reason is the higher cost of such solutions.
The cheapest option is built-in sockets. It is also the most aesthetic. The implementation of this method of mounting sockets is optimal when building or repairing an office. An alternative inexpensive option is to install wall sockets, laying mini-boxes.
Testing and guarantees
The opinion that SCS testing is a formal procedure is quite common. Many customers consider line measurement to be a warranty procedure. This is true, but only half. First, testing allows you to discover hidden defects that may go unnoticed. Secondly, this is the only way to avoid the problems of computer network applications.
Contrary to popular belief about the full compliance of SCS standards with the requirements of network protocols, this is a misconception. The transmission media settings are below application requirements. The SCS standards of classes D (100 MHz), E (250 MHz) and F (600 MHz) provide for zero - negative attenuation / total interference ratio at the upper limit of the frequency range. For working pairs of class D applications implemented in computer networks, the signal-to-noise ratio over the entire frequency range should be at least 10-19 dB, that is, one or two orders of magnitude better than the SCS standards provide. Moreover, some class D applications operate in the category 5e frequency band above 100 MHz. The frequency range of 1000BASE-T Gigabit Ethernet is 125 MHz, ATM 155 - 155 MHz.
Thus, the SCS can comply with the standards, but not provide the operation of a number of local network applications in terms of the bit error rate (BER - Bit Error Rate). This reduces the data transfer rate up to the "freeze" of the computer network.
The quality of signal transmission over SCS channels is ensured due to the reserve of parameters. To check whether the reserve is sufficient, network protocol compliance testing is carried out. For example, when using a Fluke cable analyzer (sample report), the baseline/channel is confirmed to conform to eleven network protocols. This means that any lower-class applications can also be used.
Line testing
Warranty certificate SCS ITT NS&S (UK)
Warranty certificate SCS Panduit / Belden (USA)
After installation is completed, all SCS lines are subject to testing. Design documentation with test results is provided to the SCS manufacturer. After verification, a warranty certificate is issued. The warranty period for SCS is 10-25 years. In particular, for ITT NS&S and Panduit - 25 years. Warranties for the power supply system from one to three years are provided by the installation companies.
Problem of choice
A tender is held to select a contractor. The customer determines the category of SCS, the type of shielding, the availability of guarantees, leaving all other issues to the discretion of the bidders. Bidders must convince the customer of the best quality / price ratio of the proposed solution. The choice of SCS contractors often determines the choice of the manufacturer of the system itself. Companies offering different systems price several SCS options from different manufacturers.
The quality of the SCS consists of a reserve of parameters provided by the manufacturer, as well as the qualifications of the performers performing the installation.
The reliability and performance of the cable system largely depends on the implemented design solutions. For example, the length of the cables will be minimal, which directly affects the operation of the local network. The shorter the channel length, the lower the signal attenuation, the better the signal-to-noise ratio. It is advisable to shield the lines of the maximum length. Design is based on a large body of rapidly evolving standards. Therefore, the choice of the system, cable categories, type of connectors, shielding, reasonable redundancy of SCS parameters are important. This reflects the prospects for the growth of network needs, the load of the Customer's local network.
To mount the SCS, you need to prepare cable channels, carefully lay the cables, and connect them to the connectors. Connection requires unweaving pairs, that is, unbalancing, or, in other words, reducing the quality characteristics of the system. Most often, negative test results are caused by the installation of connectors. Good qualifications of installers, verified by test results, solves the problem. There are other possibilities. Modular connectors from a number of manufacturers minimize the risk of unbalance through special mounting technology.
High-quality SCS, a reserve of functional parameters ensure long-term trouble-free operation of the local network, which guarantees a quick return on investment, increasing the efficiency of the organization.
The structured cabling system (SCS) is the fundamental base throughout the existence of the information network. It is the foundation upon which the functioning of all applications depends (Figure 81). A properly designed, installed and managed cabling system reduces the cost of any organization in all phases of its life.
Rice. 81. Comparative indicators of the average lifetime of elements of a distributed information processing system
According to statistics, imperfect cable systems are the cause of up to 70% of all information network downtime. Even though cabling typically outlasts most other network components, it costs only 5% of the total investment in an information network. Thus, using structured cabling is a very compelling way to invest in the performance of any organization or company.
The cabling system is the network component with the longest lifetime, longer than only the building frame. Standards-based cabling guarantees long-term network performance and support for all digital applications, providing a return on investment over the life of the network.
Hierarchy in cabling
A Structured Cabling System (SCS) is a set of switching elements (cables, connectors, connectors, cross panels and cabinets), as well as a technique for their joint use, which allows you to create regular, easily expandable communication structures in computer networks.
A structured cabling system is a kind of "constructor", with the help of which the network designer builds the configuration he needs from standard cables connected by standard connectors and switched on standard cross panels. If necessary, the connection configuration can be easily changed - add a computer, segment, switch, remove unnecessary equipment, and also change connections between computers and hubs.
When building a structured cabling system, it is understood that every workplace in the enterprise must be equipped with sockets for connecting a phone and a computer, even if this is not currently required. That is, a good structured cabling system is built redundant. This can save money in the future, since changes to the connection of new devices can be made by reconnecting already laid cables.
A structured cabling system is planned and built hierarchically, with a main line and numerous branches from it (Fig. 82).
Rice. 82. Structured Cabling Hierarchy
This system can be built on the basis of already existing modern telephone cable systems, in which cables, which are a set of twisted pairs, are laid in each building, bred between floors, a special cross cabinet is used on each floor, from which wires in pipes and ducts are brought to each room and are divorced by sockets. Unfortunately, in our country, not even in all newly built buildings, telephone lines are laid with twisted pairs, so they are unsuitable for creating computer networks, and in this case the cable system must be rebuilt.
A typical hierarchical structure of a structured cabling system (Figure 83) includes:
horizontal subsystems (within the floor);
vertical subsystems (inside the building);
campus subsystem (within the same territory with several buildings).
Rice. 83. Structure of cable subsystems
The horizontal subsystem connects the cross cabinet of the floor to the user's sockets. Subsystems of this type correspond to the floors of the building. The vertical subsystem connects the cross cabinets of each floor with the central control room of the building. The next step in the hierarchy is the campus subsystem, which connects several buildings to the main equipment room of the entire campus. This part of the cable system is commonly referred to as the backbone.
Using a structured cabling system instead of chaotic cabling offers many benefits to a business.
Versatility. A well-thought-out structured cabling system can become a single environment for transmitting computer data in a local area network, organizing a local telephone network, transmitting video information, and even transmitting signals from fire safety sensors or security systems. This allows you to automate many processes of control, monitoring and management of business services and life support systems of the enterprise.
Extended service life. A well-structured cabling system can be obsolete for 15 years.
Reduce the cost of adding new users and changing their placements. It is known that the cost of a cable system is significant and is determined mainly not by the cost of the cable, but by the cost of laying it. Therefore, it is more advantageous to carry out a one-time job of laying the cable, possibly with a large margin in length, than to carry out laying several times, increasing the length of the cable. With this approach, all work on adding or moving a user comes down to connecting the computer to an existing outlet.
Possibility of easy network expansion. The Structured Cabling System is modular and therefore easy to expand. For example, you can add a new subnet to a backbone without affecting existing subnets. You can replace a single subnet cable type independently of the rest of the network. A structured cabling system is the basis for dividing a network into manageable logical segments, since it is itself already divided into physical segments.
Providing more efficient service. A structured cabling system makes maintenance and troubleshooting easier than with a bus cabling system. In the bus organization of the cable system, the failure of one of the devices or connecting elements leads to a hard-to-localize failure of the entire network. In structured cabling systems, the failure of one segment does not affect the others, since the segments are interconnected using hubs. Hubs diagnose and localize the faulty section.
Reliability. A structured cabling system has increased reliability, since the manufacturer of such a system guarantees not only the quality of its individual components, but also their compatibility.
The first structured cabling system to have all the modern features of this type of system was the SYSTIMAX SCS system from Lucent Technologies (formerly a division of AT&T). And today Lucent Technologies owns the main share of the world market. Many other companies also produce quality structured cabling systems, such as AMP, BICC Brand-Rex, Siemens, Alcatel, MOD-TAP.
Basic concepts
Structured Cabling System (SCS)- this is a universal cable system of a building, a group of buildings, designed to be used for a sufficiently long period of time without restructuring, SCS involves the replacement of the entire cable system and building / building systems ..
The versatility of the SCS implies its use for various systems:
- computer network;
- telephone network;
- security system;
- fire alarm
- others.
Such a cable system is independent of the terminal equipment, which allows you to create a flexible communication infrastructure of the enterprise. A structured cabling system is a collection of passive communication equipment:
Cable- this component is used as the SCS data transmission medium. The cable is divided into shielded and unshielded.
Sockets- this component is used as an entry point to the cable network of the building.
Patch panels- are used to administer cable systems in the switching centers of the floors and the building as a whole.
Patch Cords- are used to connect office equipment to the cable network of the building, organize the structure of the cable system in switching centers.
The principle of building SCS
SCS - covers the entire space of the building, connects all points of information transmission media, such as computers, telephones, fire and security alarm sensors, video surveillance and access control systems. All these facilities are provided by an individual entry point into the overall building system. Lines, separate for each information outlet, connect the entry points to the floor switching center, forming horizontal cable subsystem. All storey switching nodes are connected by special trunks in the switching center of the building. External cable lines are also brought here to connect the building to global information resources, such as telephony, the Internet, etc. This topology allows you to reliably manage the entire building system, provides flexibility and simplicity of the system, as well as its unification.
1 - Office equipment- computer, telephone, fax and other peripheral equipment.
2 - Cabling- it is laid along embedded channels inside walls, along decorative cable ducts inside rooms, along trays behind false ceilings or under false floors.
3 - Switching node- designed for installation and use of switching equipment of the cable system, for centralizing external and internal cable entries, for connecting the cable system with active network or other equipment.
4 - Vertical cabling
5 - Service technical means
Workplace- the area where the technical means of the user are installed, connected to the cable network of the building. The workplace is equipped with at least two information outlets, since a typical office workplace contains at least a user's computer and his phone. To connect them to the SCS, sockets with a standardized RJ-45 connector and patch cords with a length of 1 to 5 meters are used.
Horizontal cabling- cable lines connecting the workplace with the switching node of the floor. Horizontal cabling, based on copper conductors, uses a four-pair single-core cable in various designs. Under normal conditions, unshielded cable is used, and with increased requirements for electromagnetic radiation, compatibility or confidentiality, shielded cable. In some, special cases, it is possible to use a fiber optic cable as a horizontal cable system, providing increased protection against electromagnetic radiation and protection against unauthorized access.
Floor Switching Unit- the area where the horizontal cabling lines converge, the switching equipment is located and the floor's cabling system is administered. Administration refers to making changes and additions to existing configurations. The basis of such centers are patch and cross-panels. For ease of installation and ease of use, switching equipment is placed in special cabinets and racks, to which all cable lines are connected. Cabinets also perform the function of restricting access to switching equipment.
Vertical cabling- cable lines connecting the switching node of the floor with the switching center of the building.
Backbone subsystem- a subsystem of a building complex, which can be built from copper and/or fiber optic types of cable, and which integrates the cable systems of buildings.
In each particular building, in general, there are three SCS subsystems: a vertical cable subsystem, a horizontal cable subsystem, and a workstation subsystem. For sufficiently large buildings, with a large number of jobs on the floors, all these three subsystems are present in an explicit form. For relatively small buildings with a limited number of jobs, it is recommended to organize one SCS switching node, where all horizontal cabling converges. In this case, the vertical cable subsystem may be absent or may be of a degenerate nature, in which the vertical cable subsystem is represented by a set of patch cords connecting the ports of the floor switches of the LAN (switches for connecting workplaces) to the ports of the central (backbone) switch.
Requirements for the design of SCS:
SCS should be designed with redundancy in terms of the number of connections.
A structured cabling system must be made in accordance with standards - international, European, American. such as ANSI/EIA/TIA 568, ANSI/EIA/TIA 569
The workplace must have at least one LAN connection and one telephone network connection
The maximum horizontal wiring distance should not exceed 90m;
The equipment used to build the SCS must comply with at least the fifth category.
Each link of the cable system from the point of connection of the terminal equipment to the point of connection to the patch panel must be tested for belonging to at least the fifth category.
SCS should provide fast switching of horizontal wiring lines and building mains
Cable laying in the corridors should be carried out behind a false ceiling, if any, and in its absence - in specialized cable channels (boxes) or in existing mortgages; in the working premises, the cable is supplied to the workplaces in cable channels.
