Shulou(Shulou.com)06/01 Report--

(sun Huiyong / tr. by Phil Newell)

Market background: in the last 5-6 years, the construction of China's data center is in the stage of rapid growth, and according to the forecast of the third-party survey agency AMI, the construction of domestic data center will continue to be in the rapid growth channel in the next five years or more. According to the report, the compound annual growth rate of data center cabling market in Asia-Pacific region will reach 32.8%. China's compound annual growth rate is expected to reach 37.5%, which is 23.9% higher than the compound annual growth rate of the overall integrated cabling market. China's data center cabling market is expected to reach 9-1 billion yuan in 2011. In recent years, China's domestic traditional cabling market has gradually evolved from a completely dominated phenomenon by international cabling brands to a pattern in which domestic brands compete with international brands, while in the data center cabling market, especially in the large and medium-sized data center cabling market, according to statistics, 70% of the market share is monopolized by about 5-6 international cabling brands specializing in the data center field. Due to the professionalism of products in the data center cabling market, the requirements for product quality and reliability are much higher than those in the traditional cabling market, especially in the application technology of optical fiber products, there is still a considerable gap between cabling brands. the construction and application of large-scale data center projects has greatly promoted the development of optical fiber cabling product technology, and will put forward new and higher requirements for data center optical fiber cabling. And the emergence of new technical topics promotes the development of data center cabling technology, guides the direction of data center cabling product technology, and then produces the mainstream effect in the cabling market. Key words: data center multimode optical fiber cabling technology trend one, the application of optical fiber technology and the development of data center cabling systems need to constantly improve bandwidth, paving the way for fast-growing networks (such as core layer network, aggregation layer network and SAN storage network) transmission applications in advance, while the use of optical fiber transmission can provide a guarantee for continuous exploration of bandwidth potential. Compared with single-mode fiber, the lower comprehensive cost of active + passive multimode fiber will promote the absolute advantage of multimode fiber in the application of data center. More than 85% of optical fiber wiring systems in large and medium-sized data centers use multimode fiber. In August 2009, TIA officially approved OM4, a new category of EIA/TIA492AAAD multimode fiber standard, which provides a good development prospect for a large number of applications of multimode fiber in the future. multimode fiber develops from OM1 to OM2, OM3 after VCSEL laser optimization technology to OM4, and the bandwidth increases step by step. the corresponding relationship between bandwidth and 10G transmission distance is shown in the following figure (1). Figure (1) with the release of IEEE 802.3ba 's new Ethernet 40G/100G standard in June 2010, the application of multimode fiber in the data center field will turn a new page. The high-speed transmission of 40G and 100G will no longer rely solely on single-mode WDM serial transmission, the new generation Ethernet 40G/100G standard will adopt OM3 and OM4 multimode fiber multi-channel parallel transmission. Compared with the single-mode WDM serial transmission mode, the total cost on the 40G/100G (including active equipment, optical module, passive components) on the single-mode parallel transmission mode only accounts for 1 / 3 and 1 / 10 of the single-mode system, respectively. It can be seen that the multimode advantage is very obvious, and the market application trend is usually driven by cost and price factors to determine which technology mode can get the largest application in the market. The transmission mode of the multimode fiber 40G adopts the rate 4*10Gbp=40Gbps of each pair of optical fibers supporting 10Gbps, which requires a total of 8 fibers for each four fibers to send and receive. 100G uses 10 fibers for sending and receiving 10*10Gbps=100G, and a total of 20 fibers are used. The multi-core connection system using standard MTP/MPO will better support the transmission of the new generation optical network 40G/100G. 40G and 100G are in the multimode transmission mode as shown in figure (2) below. The transmission mode of 40G is to take 4 cores on the outermost side of the 12-core MTP/MPO connector for transmission, and the middle 4-core is vacant, while in the 100G transmission mode, two 12-core MTP/MPO connectors are used to take the middle 10-core for transmission. If the MTP/MPO high-density 24-core connector is used, 100G is received and transmitted on a 24-core MTP/MPO connector. During 100G transmission, one core on each side of each of the 12 cores is vacant. 40G Transmission Mode 100G Transmission Mode Diagram (2)

As the new generation of 40G/100G optical fiber technology standards and application standards have been issued, there is a clearer choice of optical fiber types for data center planners. OM3 and OM4 optical fiber will become the mainstream of data center applications, such as table (1) shows that multimode OM3,OM4 optical fiber is applied to the corresponding transmission protocol and supporting application distance of 40G/100G, respectively. Although the transmission distance of multimode 40G/100G cannot be compared with that of single-mode fiber up to 10KM or 40KM, in the indoor application environment of data centers, it is estimated that the optical fiber link length of more than 90% of small and medium-sized data centers is less than 100m, that of large data centers is more than 70%, and that of more than 85% is less than 150m. Multimode can meet the needs of most links, with the improvement of network equipment technology. The transmission distance supported by multimode fiber is likely to be further increased in the future. Transport protocol type optical fiber type supports transmission distance 40GBase-SR4850nm VCSEL OM3 fiber 100m 40GBase-SR4850nm VCSEL OM4 fiber 150m 100GBase-SR10850nm VCSEL OM3 fiber 100m 100GBase-SR10850nm VCSEL OM4 optical fiber 150m meter (1)

The standard ANSI/TIA 568C.3 issued by the North American Telecommunications Industry Association in June 2009 defines three optical fiber connection modes for fiber connection channels composed of MTP/MPO multi-core connectors, namely TYPE- Aline TYPEMUE Bline TYPEMAE C. In 10Gbps and below transmission applications, Ethernet device ports use duplex mode, and MTP/MPO backbone links will eventually be converted to duplex type connectors such as LC,SC, etc. In the state of 40G/100G, the device port, such as QSFP, will be directly connected with the MTP/MPO connector. No matter how many optical cables are connected in the fibre Channel, and no matter what kind of TYPE connection the intermediate fiber is, the final channel connection between the device end and the device side needs to form the model state of TYPE-B, so that the channels of the device sender and receiver correspond to each other, otherwise the normal communication will not be possible. As shown in figure 3: figure 3

At present, a large number of backbone network equipment ports in the data center are switching from 1GbE to 10GbE. According to a forecast made by Intel, figure (4) taking X86 server ports as an example, a small number of 40GbE ports will be officially applied from 2011, and a large number of applications will begin after 2015. The data center cabling system, as one of the infrastructure, is different from the network equipment, which usually needs to be updated in 3-5 years, and the data center cabling system, especially the optical fiber cabling system, usually needs to support network equipment updates of more than 2 to 3 generations. therefore, the deployment and application of optical fiber cabling system must be 3-5 years ahead of the current actual network applications. According to the analysis of the application of multimode fiber in data centers by the third-party consulting firm Alan Flatman, it is predicted that the deployment of multimode fiber channel supporting 40GbE will account for a certain proportion and increase significantly year by year since 2011, as shown in figure (5) below.

Second, the development of optical fiber cabling product technology with the upgrading of optical fiber technology, the product technology of optical fiber cabling system, as the "central nervous system" of data center, is also undergoing a new generation of upgrade. from the perspective of data center cabling product technology in China's domestic market. If we regard the product line professionally applied to data center cabling optical fiber solutions developed in the five years from 2005 to 2010 as the first generation data center optical fiber cabling product technology, the data center optical fiber cabling products represented by the first generation pre-connected (or pre-terminated) product technology have been well applied and promoted during this period. Well, with the continuous release of new standards for optical fiber technology, China's large and medium-sized data center cabling market, which is monopolized by several international cabling brands, will lead the cabling product technology to enter the second generation of data centers. the share and ranking within the oligarchs may change because of the differences in the technical solutions of the new generation data center products and the different ways and effects of market operation. The second generation optical fiber wiring system of data center is composed of representative product lines, such as ultra-low loss pre-connected optical cable scheme, high-density optical fiber distribution system and bending insensitive optical fiber system. 1. Ultra-low loss pre-connection scheme pre-connection optical cable scheme has a variety of connection modes in data center cabling, and there are mainly three mainstream applications that are widely used: (1) pre-connection module with MPO-LC branches at both ends of MTP/MPO to MTP/MPO pre-connection optical cable (2) one end of the MTP/MPO to LC pre-connected optical cable is connected with a pre-connecting module containing MPO-LC branches, and the other end of the LC end is directly equipped with a LC adapter panel; (3) the two ends of the LC to LC pre-connected optical cable are directly connected to the LC adapter panel. With the official release of Ethernet 40G/100G using multi-channel optical fiber transmission standard in the future, in the future optical fiber backbone deployment in data centers, the pre-connection scheme of MTP/MPO to MTP/MPO and OM3,OM4 optical fiber will become the preferred scheme among the above three pre-connection technical schemes, which is different from the requirements of the first generation MTP/MPO connection mode. The initial application of the first generation scheme is mainly to support the application of 10GbE. According to the requirement of 10GbE Ethernet for the overall fibre Channel attenuation of OM3, it is 2.6dB, and if the overall channel attenuation of the network supporting 40G/100G in the future needs to be controlled within 1.9dB and 1.5dB respectively, the corresponding relationship between various transmission applications and channel attenuation is shown in Table (2). The single connection loss of the first generation MTP/MPO is usually only controlled within 0.75dB. Obviously, this performance will cause the problem of effective link length shortening because the channel attenuation exceeds the standard value for subsequent 40G/100G applications. S optical fiber type maximum transmission distance maximum channel attenuation 10GBase-SR850nm VCSEL OM3 optical fiber 300m 2.6dB10GBase-SR850nm VCSEL OM4 optical fiber 550m 2.6dB40GBase-SR4850nm VCSEL OM3 optical fiber 100m 1.9dB40GBase-SR4850nm VCSEL OM4 optical fiber 150m 1.5dB100GBase-SR10850nm VCSEL OM3 optical fiber 100m 1.9dB100GBase-SR10850nm VCSEL OM4 optical fiber 150m 1.5dB meter (1) Table (2)

The MTP/MPO attenuation value of the new generation data center pre-connected system will require the use of low-loss connectors. The industry will require at least a single MTP/MPO connection point attenuation value to be less than 0.5dB in order to allow the channel to play the standard defined 40G/100G maximum transmission distance. At present, different manufacturers have different levels of attenuation control for pre-connected systems. Taking the second generation VelaTM series pre-connection system launched by the German Rosenberg HDCS data center wiring system as an example, the VelaTM series pre-connection system will launch a new generation of ultra-low loss MTP connection system. The realization of ultra-low loss MTP scheme is mainly from the connector's own core insertion accuracy, grinding process, 3D geometric end face testing technology, a single multi-mode MTP connection point can be controlled below 0.3dB. The second generation pre-connected system is shown in figure (6). The second-generation pre-connected fiber optic cable with ultra-low loss provides the basic guarantee for the smooth upgrade of 40G/100G in the data center in the future. In addition to controlling the optical performance of fibre Channel, there are also new upgrades in the structure of the second generation pre-connected system. The pre-connected fiber branches will use more circular fiber branches. Compared with the previous generation of flat MTP/MPO branches, it is easier to have high-density wiring in a narrow space and the fiber bending is not directional with the disk fiber. The second-generation high-tension and small-diameter optical cable is adopted in the backbone optical fiber, which saves pipe slot space in addition to improving the tension and compression parameters of the optical cable itself. at the same time, the wiring and installation of the trunk optical cable is more convenient. The installation handles at both ends of the pre-connected optical cable can support at least 500N installation tension, which can fully meet the mechanical and reliability requirements of the data center in various installation environments. Figure (6)

2. The pre-connected optical cable of the high-density distribution system is usually installed on the wiring channel of the computer room as the backbone of the data center, and it will not be easily moved and changed once deployed. Unlike the pre-connected optical cable backbone, the optical fiber module and distribution system terminated at both ends of the pre-connected cable will need to be upgraded with the upgrade of the application. At present, the backbone of the data center is more likely to apply 10GbE, while the optical port SFP of 10GbE is more likely to use LC type port connection mode, but the subsequent 40G and 100G transmission may adopt the MTP/MPO interface mode. How to make the cabling system support not only the current needs but also the future needs? Our approach is that only the modules in the high-density distribution system need to be flexibly upgraded without the need to replace the backbone fiber link, and future upgrades of the modules in the distribution system are expected to evolve in the manner shown in figure (7) below (figure 6). Module 1 in the figure is in the form of OM3,OM4 MTP/MPO to LC that currently supports 10GbE applications; module 2 is to support 40GbE applications to improve the utilization of backbone optical fiber, the port of 2'12-core MTP/MPO is converted to 3'8-core MTP/MPO, and the application of this module can increase the utilization rate of backbone optical fiber by 50% at 40G When the network is upgraded to 100GbE, the MTP/MPO adapter panel will be directly used to upgrade the wiring system, and the MTP/MPO jumper will be directly plugged into the adapter panel and the device port. Figure (7) in addition to meeting the requirements of network upgrade applications, the pursuit of high-density cabling is always an important measure of the optical wiring system in the data center, reducing the space occupied by the wiring system in the cabinet. it will maximize the installation space of production network equipment, so as to increase the utilization rate per unit area of the computer room and the rate of return. The wiring system of the next generation professional data center will adopt a variety of wiring modes, such as the new generation wiring system specially designed for the data room can be installed in the TOR mode on the network bridge, or the data center in the under-floor wiring mode can be installed directly in the centralized area distribution system under the movable floor. The new generation of high-density wiring system mentioned above will no longer occupy the space of the cabinet. For the MDA area where optical fiber wiring is most concentrated, the data center wiring system will not only pursue higher and higher density, the maintainability of MDA area optical fiber distribution system is as important as high density, and the higher density will affect maintainability. The development direction of the new generation data center wiring system will be to achieve the best balance between high cabling density and cabling system maintainability. 3. The optical fiber jumper in the high-density distribution area of the bending-insensitive optical fiber data center is often the core of management. when the port density of the optical fiber distribution frame is higher, the management of the jumper is no longer easy. If the bending radius of the optical fiber jumper is too small, it will directly lead to the increase of the attenuation of the whole optical fiber channel. If the bend is serious, the excessive attenuation may cause the communication of the channel to be interrupted. For large and medium-sized data centers, there are thousands of jumpers in the high-density wiring area, so it is difficult to ensure that the management of each jumper can be within the bending radius of more than 10 times the diameter of the optical cable required by the standard. For data centers, the reliability of network operation is one of the fatal elements of data centers. Because of this, the new generation of data centers will increasingly use bending-insensitive optical fiber systems to solve this problem. Unlike the traditional jumper, using the bending insensitive fiber jumper, when the bending radius of our optical fiber is 7.5mm winding 2-3 turns, the attenuation does not even exceed the 0.1dB, while under the same conditions, if the ordinary optical fiber jumper is used, the attenuation may have exceeded 0.6dB, the following figure (8) shows the bending state and real-time test of the Rosenberg HDCS system VelaTM bending insensitive fiber jumper. Figure (8)

As mentioned earlier, when OM3,OM4 cabling needs to be able to support the next generation 40G/100G network, and with the upgrade of each generation of network applications, the standard has more stringent requirements for maximum channel attenuation. Jumper is the core of cabling system management, movement and change. When the jumper system uses bend-insensitive fiber, it will increase the reliability of the overall fibre Channel by one level. The way of using bend-insensitive fiber to improve the reliability of fiber physical channel is more cost-effective than other ways. From this point of view, bend-insensitive fiber will be more and more widely used in the new generation data center. In conclusion, the progress of optical fiber technology, especially the continuous evolution of multimode optical fiber standards, has laid the foundation for the development of data center network technology. as a data center network infrastructure, data center optical fiber cabling system has become a new topic in the cabling industry. compared with traditional cabling, it is becoming more and more specialized, and it is also gradually affecting the competitive pattern of brands in the cabling industry. The continuous introduction of a variety of product application technologies, such as a new generation of optical fiber pre-connection system, high-density wiring technology and bending-insensitive optical fiber, provide a solid foundation for the future upgrading and development of the data center network. Literature summary: 1, "China Comprehensive cabling Market Development report" Comprehensive cabling working Group, March 2010, 2, Ensuring 40max 100G Performance, TIA, 2010 OM4 Fiber Dec 3, OM4 Fiber: The Next Generation of Multmode Fiber,TIA, 2010 Jun

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