Analysis of the development trend of optical fiber cabling technology

The data center cabling system needs to continuously increase the bandwidth to lay a good road for the rapid growth of network transmission applications, and the use of optical fiber transmission can provide guarantee for the continuous exploration of the bandwidth potential. Compared with single-mode fiber, due to the lower active/passive cost of multimode fiber technology, multimode fiber will have an absolute advantage in data center applications, with over 85% of fiber optic cabling in large and medium-sized data centers. The system uses multimode fiber.

market background

In the recent 5-6 years, the construction of data centers in China is in a period of rapid growth. According to the AMI forecast of a third-party investigation agency, the construction of domestic data centers will continue for a period of 5 years or even longer. In the fast-growing channel, according to the report, the compound annual growth rate of the cabling market in the Asia-Pacific data center will reach 32.8%, and China's compound annual growth rate is expected to reach 37.5%, which is 23.9 times higher than the compound annual growth rate of the overall cabling market. %, China's 2011 data center cabling market will be expected to reach 910 million yuan.

The domestic traditional wiring market in China has been gradually dominated by the international cabling brand in recent years and gradually evolved into a domestic brand and international brand division. In the data center cabling market, especially large and medium-sized data center cabling market, according to statistics, 70% of the market The share is formed by an oligopoly market of about 5-6 brands that are specialized in the field of data centers. Due to the professionalism of the data center cabling market, product quality and reliability requirements are much higher than those of traditional cabling markets. In particular, there are still gaps between cabling brands in the application technology of optical fiber products, and large-scale data center projects The construction and application will greatly promote the development of fiber cabling product technology, put forward new and higher requirements for data center fiber cabling, and generate new technical issues to promote the development of data center cabling technology, and guide the data center cabling product technology The direction then has a mainstream effect in the wiring market.

Application and Development of Fiber Optic Technology

The data center cabling system needs to continuously improve its bandwidth for the rapid growth of the network (such as the core layer network, convergence layer network and SAN storage network) transmission applications ahead of the road, and the use of fiber optic transmission can continue to explore the potential of bandwidth to provide protection. Compared with single-mode fiber, due to the lower active/passive cost of multimode fiber technology, multimode fiber will have an absolute advantage in data center applications, with over 85% of fiber optic cabling in large and medium-sized data centers. The system uses multimode fiber. In August 2009, TIA formally approved the launch of OM4, a new category of EIA/TIA492AAAD multimode fiber standard, which provides a promising development prospect for the future use of multimode optical fibers in a large number of applications. Multimode optical fibers from OM1 to OM2 adopt VCSEL laser optimization. After the technology, the OM3 went to the OM4 to develop four stages. The bandwidth is also upgraded step by step. The relationship between the bandwidth of each level and the distance of the 10G transmission is shown in the following figure (1).

With the release of IEEE 802.3ba new Ethernet 40G/100G standard in June 2010, the application of multimode optical fiber in the data center sector will open a new page, and the high-speed transmission of 40G and 100G will no longer rely solely on single-mode adoption. High-cost WDM serial transmission, the new generation of Ethernet 40G/100G standard will use OM3 and OM4 multi-mode fiber multi-channel parallel transmission, this multi-mode and parallel transmission mode compared to single-mode WDM serial transmission The overall cost of 40G/100G (including active equipment, optical modules, and passive components) accounts for only 1/3 and 1/10 of the single-mode system, showing that the multi-mode advantage is very obvious, and the market application tends to be common. It is driven by cost and price factors and decides which technology model can achieve the largest application in the market.

The transmission mode of multi-mode optical fiber 40G adopts a rate of 4*10Gbp=40Gbps for each pair of optical fibers. It requires 4 optical fibers to transmit and receive a total of 8 core optical fibers, and 100G uses 10 optical fibers to transmit and receive 10*10 Gbps=100G. A total of 20 core fibers are used. The multi-core connection system using standard MTP/MPO will better support the transmission of 40G/100G in the new generation optical network. The transmission modes of 40G and 100G in the multi-core fiber are as shown in the following figure (2). The 40G transmission mode is based on the 12-core MTP/MPO connector with 4 cores on the outermost sides for transmission. The middle 4 cores are in the idle state, and the 100G transmission mode uses two 12-cell MTP/MPOs. The middle 10 pins of the connector are used for transmission. If a MTP/MPO high-density 24-pin connector is used, 100G reception and transmission are performed on a 24-pin MTP/MPO connector. In the 100G transmission, one core per one side of each 12 cores is in an empty state.

As the standards and application standards for the new generation of 40G/100G optical fiber technologies have been released, the data center planners have a clearer choice of optical fiber types. OM3 and OM4 optical fibers will become the mainstream of data center applications. The multimode OM3 is shown, and the OM4 fiber is applied to the 40G/100G corresponding transmission protocol and supporting application distance. Although the transmission distance of the multimode 40G/100G cannot be compared with that of the single mode fiber up to 10KM or 40KM, it is in the data center. In the indoor application environment, according to statistics, more than 90% of optical fiber links in small and medium-sized data centers have a length of less than 100 meters, and 70% of large data centers have a fiber link length of less than 100 meters, and more than 80% of the length is less than 125 meters. The requirements of most links can be met. With the advancement of network equipment technologies, the transmission distance supported by multimode optical fibers may increase further in the future.

Transmission Protocol Type Fiber Type Supports Transmission Distance:

40GBase-SR4850nmVCSELOM3 optical fiber 100 meters

40GBase-SR4850nmVCSELOM4 fiber 125 meters

100GBase-SR10850nmVCSELOM3 optical fiber 100 meters

100GBase-SR10850nmVCSELOM4 fiber 125 meters

Standard ANSI/TIA568C released by the North American Telecommunications Industry Association in June 2008. 3 Three types of optical fiber connection modes are defined for optical fiber connection channels consisting of MTP/MPO multi-fiber connectors: TYPE-A, TYPE-B, and TYPE-C. Ethernet devices are used for transmissions of 10 Gbps or less. The port adopts the duplex mode. The MTP/MPO trunk links will eventually be converted to duplex type connectors such as LC, SC, etc. In the 40G/100G state, the device ports such as QSFP will be directly connected to the MTP/MPO connectors. Regardless of whether the optical fiber is usually connected by several optical cables, and regardless of which TYPE connection method is adopted for the intermediate connection optical fiber, the final channel connection mode between the device end and the device end of the 40G/100G needs to form a TYPE-B model state. Make the channel between the sender and receiver of the device correspond to each other; otherwise, the device cannot communicate normally.