In the structured cabling system, optical fiber not only supports FDDI trunk, 1000Base-FX trunk, 100Base-FX to the desktop, ATM trunk and ATM to the desktop, but also supports CATV/CCTV and fiber to the desktop (FTTD), so it and copper cable Together they become the protagonists in structured cabling.
Today, there are two main international popular wiring standards, one is the North American standard EIA/TIA-568A; the other is the international standard ISO/IECIS11801. EIA/TIA-568A and ISO/IECIS11801 recommend using 62.5/125um multimode optical cable, 50/125um multimode optical cable and 8.3/125um multimode optical cable.
Single-mode fiber and multi-mode fiber can be easily distinguished from the size of the core. The core of single-mode fiber is very small, about 4-10um, and only transmits the main mode. In this way, modal dispersion can be completely avoided, so that the transmission frequency band is very wide and the transmission capacity is large. This fiber is suitable for large-capacity, long-distance fiber-optic communications. It is the inevitable trend of the future development of optical fiber communication and light wave technology.
Multimode fiber is further divided into multimode abrupt fiber and multimode graded fiber. The former has a larger core diameter and more transmission modes, so the bandwidth is narrower and the transmission capacity is smaller. Wide and larger transmission capacity, the latter is generally used at present.
At present, the wavelength range of light waves used in optical communication is in the near-infrared region, with a wavelength of 0.8 to 1.8um. It can be divided into short wavelength band (0.85um) and long wavelength band (1.31um and 1.55um). Because optical fiber communication has a series of excellent characteristics, optical fiber communication technology has developed extremely rapidly in recent years. It can be said that this emerging technology is an important symbol of the new technology revolution in the world, and it is also the main transmission tool of various information networks in the future information society. 
Several bands of light waves used in optical fiber wiring: 800nm-900nm short-wave band; 1250-1350nm long-wave band and 1500-1600nm long-wave band.
In these bands, the optical fiber transmission performance is the best, especially in the center wavelength of the band. Therefore, multimode fibers operate at 850nm or 1300nm, while singlemode fibers operate at 1310nm or 1550nm. The two regulations are not very different, both are very strict. Therefore, the longest distance of optical fiber as the backbone wiring is also specified. When the optical cable is used in the backbone, at least 6-core optical cable should be used in the wiring room of each floor, and 12-core optical cable should be used for advanced applications. This is considered from three aspects: application, backup and expansion.