Discussion on the integrated optical fiber network cabling solution of Enterprises

Optical fiber is short for optical fiber. It consists of a fine glass wire with a diameter of about 1mm. Because of its high transmission bandwidth and communication capacity, especially not subject to electromagnetic interference, it is favored by the enterprise LAN Integrated Wiring. Based on the comprehensive wiring specifications and the characteristics of Enterprise LAN construction, the selection of optical fiber cabling materials and the design of cabling solutions are discussed, and analyzed and summarized based on the experiences in the Cabling Process of optical fiber cables.

1 optical fiber selection

At present, the market has a wide range of integrated wiring products, and the selection of optical fiber is the first problem we are facing. We should consider from the following aspects:

1.1 select suitable application optical fiber based on performance requirements

Optical fiber transmission modes can be divided into single-mode (SMF) and multi-mode (MMF ).

The core diameter of multimode optical fiber is 50 or 62.5 μm, and the outer diameter of the package layer is 125 μM, Which is 50/125 μm or 62.5/125 μM. The core diameter of a single-mode optical fiber is 8.3 μm, and the outer diameter of the package layer is 125 μM, Which is 8.3/125 μM. The Multi-Mode Optical Fiber Core is coarse and can transmit light in multiple modes. However, the DIQ dispersion is large, which limits the frequency of digital signal transmission and is more serious as distance increases. Therefore, multimode optical fiber transmission distance is relatively close, generally only a few kilometers.

Single-Mode Optical Fiber center glass core is fine, the core diameter is generally 9 or 10 μm, the outer diameter of the package layer is 125 μM, expressed as 8/125 μm, 9/125 μm, 10/125 μm, only one mode of light can be transmitted. Therefore, it is suitable for remote communication, but its color dispersion plays a major role. In this way, the single-mode optical fiber has a high requirement on the spectral width and Stability of the light source, that is, the spectral width must be narrow, good stability.

1.2 select high-quality optical fiber based on standard levels

Because traditional multi-mode optical fiber can only transmit tens of meters in 10 Gigabit Networks, ISO/IEC 11801 has developed a new standard class of multi-mode optical fiber (OM3), which is used in combination with 10-Gigabit applications. Both the LED and laser bandwidth modes are optimized by OM3 optical fiber, and must be strictly tested and certified by DMD. The new standard optical fiber cabling system supports at least 10 Gigabit transmission to 300 meters in multi-mode, and more than 10 km in single mode (NM supports 40 km transmission ).

1.3 select the most economical transmission frequency window from the perspective of cost effectiveness

The optical fiber working wavelength is 850nm, 13l0nm, and 1550nm. The optical fiber loss decreases with the increase of the wavelength. The loss of 1.31 nm is generally dB/km, and the loss of μm is usually 0.35dB/km, the loss of 1.55 μm is generally 0.20dB/km, which is the lowest loss of optical fiber, and the loss of more than 1.65 μm wavelength tends to increase. The main parameters of 1310nm conventional single-mode optical fiber are determined by the ITU ITU-T in G652 recommendations, and l310nm is exactly a low-loss window of the optical fiber.

Therefore, this type of optical fiber is also called G652. G.652.D is the latest indicator of single-mode optical fiber. It is the strictest indicator of all G.652 levels and is fully backward compatible. If only G.652 is specified, it generally means G.652.A's performance specification, which should be paid special attention.

SYSTIMAX Solutions has rich experience in the field of optical fiber cabling. After years of research and experiment, the SYSTIMAX laboratory analyzes the cost of the complete Optical Fiber System and draws the following conclusion: the optimized application of NM on Multimode Optical Fiber maximizes user benefits, followed by the application of NM on single-mode optical fiber.

1.4 optical fiber selection not only depends on the number of Optical Fiber cores and the type of optical fiber, but also depends on the use environment of the optical fiber.

If the transmission distance is less than 2km, you can select multi-mode optical fiber, more than 2km can be used for relay or single-mode optical fiber. The flame retardant, toxic, and smoke Characteristics of the optical fiber used in buildings should be paid attention to during selection. Flame Retardant but smoke type is optional in the pipe or forced ventilation; if it is exposed, flame retardant, non-toxic and smoke-free type should be selected. Armored optical cables should be used for direct burial of outdoor optical cables. Black plastic outer sheath with two or more reinforced bands can be used for optical fiber overhead.

Based on the above analysis, regardless of single-mode and multi-mode, users should invest the best performance at the lowest price from the perspectives of application, transmission distance, foresight, and cost.

2 Cable Laying

The optical fiber cables can be divided into 4-core, 6-core, 8-core, and 12-Core Cables. The cables can be divided into overhead, directly buried, and multi-mode cables (less than 2 kilometers) based on the supported distance), single-mode (2 km to dozens of kilometers ). Enterprise Local Area Networks generally use troughs, heating pipe troughs, or underground multi-mode optical fiber cables in the park. An overhead single-mode optical fiber is considered in a long distance.

Signal attenuation is also inevitable in optical fiber cabling. There are two internal and external reasons for its generation: the internal attenuation is related to the optical fiber material, and the external attenuation is related to the construction and installation. Therefore, it should be noted that:

(1) The first thing we should do is to perform optical fiber connection and maintenance by strictly trained technical personnel in accordance with the optical fiber construction specifications.

(2) complete design and construction drawings must be provided to facilitate the construction and future inspection. During construction, always be careful not to make the optical cable under heavy pressure or be hurt by hard objects; in addition, the traction should not exceed the maximum laying tension.

(3) the turning radius of an optical fiber must be 20 times the diameter of the optical fiber. When the optical fiber goes through the wall or the floor, the plastic tube should be added with the protection port, and the tube should be filled with a flame retardant filler. A certain amount of plastic pipes can be laid in advance in a building.

(4) When the optical fiber is applied to the trunk network, each floor must use at least 6-core optical fiber cables. It is best to use 12-core optical fiber cables for advanced applications. This is from three aspects: application, backup, and expansion.

(5) for long-distance optical fiber laying, the most important thing is to select a proper path. Here, not necessarily the shortest path is the best, but also pay attention to the right to use the land, the possibility of erection or burial.

3 installation and wiring scheme of optical fiber trunk box

The optical fiber trunk box is the final joint of a optical fiber cable. One end is the optical fiber cable and the other is the pigtails. As a result, a optical fiber cable is split into a single optical fiber device and installed in the user optical cable trunk box on the wall, its function is to provide fusion of optical fiber and optical fiber, fusion of optical fiber and pigtails, and optical connector handover. It also provides mechanical and environmental protection for optical fibers and their components, and allows proper inspection to maintain the highest standard of Optical Fiber management. The hosts box is usually installed on a rack of 19 inch and can accommodate a large number of optical fiber terminals.

Common cable boxes include wall-mounted Optical fiber trunk boxes, rack-mounted Optical fiber Distribution boxes, ODF units (Optical Distribution Frame), and Optical fiber transfer boxes, specific applications should be taken into account in terms of project scale, cost, and scalability.

The cable trunk box is mainly used for the fixation of Optical Cable terminals, the fusion of optical fiber cables and pigtails, and the reception and protection of residual fiber.

The optical distribution frame is used for the end-to-end and distribution of local trunk cables in the optical fiber communication system to facilitate the connection, allocation and scheduling of optical fiber lines.

The enterprise's optical fiber topology is usually star. The cabling scheme selects the type of optical fiber trunk box based on the project scale and budget. In the star network layout, the optical fiber is collected to the network center from various information points:

(1) The solution with a relatively small number of optical fibers and a simple star layout adopts the "Network Center rack-mounted optical fiber distribution box to rack-mounted optical fiber distribution box", which features the lowest engineering cost, to add new optical fiber cables, the corresponding optical fiber distribution frames must be added to the network center, with poor scalability;

(2) The solution with a large number of optical fibers and simple star layout adopts the "Network Center ODF unit to rack-mounted optical fiber distribution box"; the project cost is moderate, and the scalability is moderate;

(3) For scenarios with a large number of optical fiber cables and complex star layout, the "Network Center ODF unit to optical fiber junction box to rack-mounted optical fiber distribution box" is adopted. The project cost will increase due to the use of optical fiber transfer boxes, good scalability.

In addition to cost and scalability, the solution also considers the geographical characteristics of the network center data center and each information point. If the network center is in the center of the campus, the second solution can better meet the needs. If the network center is in a certain corner of the park, the information points are relatively concentrated and far from the network center, the third solution can be considered, it is easy to maintain and reduces the construction complexity.