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

I. Preface

According to a recent report released by Cisco, the number of connected devices worldwide is expected to increase from 5 billion today to 15 billion by 2015, and global monthly Internet traffic will increase from 1 exabyte in 2004 to 80 exabytes (1 exabyte = 1 billion GB) in 2015. In the face of such a large amount of Internet equipment and data traffic, it is bound to be supported by a corresponding number of basic cabling systems, especially in the Internet, finance, telecommunications and other industries where data traffic is relatively concentrated. The traditional cabling system has been difficult to meet the operational needs of enterprises, so the construction of data center, as a data processing center, will be the focus of network infrastructure in the future. Due to the high requirements for the quality of cabling products and the construction level of the system in large data centers, cabling enterprises have specialized division of labor. At present, most of the large data center cabling projects in China are concentrated in enterprises that specialize in providing data center cabling solutions. About 5-6 international cabling brands, such as Rosenberg, have more advantages than traditional cabling brands to get project opportunities. These few data center cabling companies account for about 70% of the large data center cabling market. Because of the centralized market characteristics, many traditional cabling practitioners have little opportunity to go deep into the data center cabling technology. Compared with the traditional structured cabling of buildings, the cabling technology of data center has more technical details and application characteristics, especially for the new employees in the cabling industry, they may even be confused when they encounter a data center project. Although there is no lack of professional papers introducing data centers in the industry, too professional introductions often make it difficult for beginners to understand. In order to enable more people to care about and understand the data center, this article only discusses some basic knowledge in the data center cabling system. Second, if the relevant technical standards of the data center want to understand the cabling structure of the data center, we should first be clear about the relevant standards followed by the cabling of the data center. At present, the commonly used data center cabling technical standards are shown in Table 1.

At present, the authoritative standards for computer room design at home and abroad are TIA-942 "data Center Communication facilities Standard" of American Communications Industry Association and Chinese national standard GB50174 "Design Code of Electronic Information system computer Room". TIA-942 standard combines the advantages of previous relevant standards and specifications, and makes up for the information gap in the previous data center design and construction stage. Comprehensive consideration is given to the coexistence of multiple applications such as electrical systems, HVAC (heating, ventilation and air conditioning), fire detection and suppression, safety, etc., in telecommunications infrastructure and space. GB50174 "Code for the Design of Electronic Information system computer Room" is a national compulsory standard which is more suitable for China's national conditions on the basis of drawing lessons from the relevant contents of TIA942 standards. 3. Data center wiring structure depending on the size, the data center can be a group of buildings, buildings or part of a building, which is mainly used to accommodate the computer room and its supporting space. Functionally, the data center is the center of electronic information storage, processing and circulation, and the information center of enterprises and institutions. The data center cabling discussed in this paper mainly refers to the structured cabling of the computer room, including server room, network computer room, storage room and other functional areas. Compared with the traditional structured cabling which consists of six subsystems, the data center computer room wiring system is divided into: main wiring area MDA, intermediate wiring area IDA, horizontal wiring area HDA, regional wiring area ZDA and equipment wiring area EDA and so on. The overall topology of TIA-942-A large data center cabling is shown in figure 1.

The cabling system structure described in the TIA942 standard is a widely used implementation scheme architecture in the computer room wiring project at present. The following takes this as an example to introduce the specific components and technical points of each part of the cabling system. The MDA main distribution area, that is, the core switching area, connects the backbone wiring of each layer from the intermediate distribution area, the horizontal distribution area, as well as between telecommunications and near lines, and is the core wiring area of the data center. To some extent, MDA is equivalent to the equipment subsystem of building wiring. IDA intermediate wiring area, for large data centers that occupy multiple buildings, multiple floors or multiple rooms, often involves the wiring of IDA intermediate wiring area, that is, aggregation exchange area. For some small and medium-sized data centers, the intermediate distribution area of IDA is not necessary. HDA horizontal wiring area, is the horizontal management area of the data center, generally located at one or both ends of each row of cabinets, so it is often referred to as column cabinets, or in the middle of each row of cabinets. Each horizontal distribution area is calculated according to the number of equipment cabinets managed, generally no more than 15; when centralized management is adopted, the management points generally do not exceed 2000 points. In data center cabling, there are corresponding column cabinets in each area, such as main wiring area, PC server area, small computer area, storage area and so on. The function of a horizontal wiring area is similar to that of a floor management room (IDF) in building wiring. ZDA regional distribution area, ZDA is the only area in the entire data center wiring that does not contain source equipment, generally only in the large data center computer room, there are equipment that need to be moved or changed frequently. The ZDA can be a cabinet or rack, or you can connect the cables through a rendezvous point (CP). EDA equipment wiring area, equipment wiring area refers to the wiring of PC servers, minicomputers, storage devices, switches, KVM and other network devices. In order to improve the stability of the network equipment in the data center and reduce the jumper plug at the end of the network equipment as much as possible, the network switch port and the wiring equipment port in the general horizontal distribution area are interconnected by cross-connection. EDA is the equivalent of a workspace in a data center. Fourth, data center computer room level when discussing the data center, we often hear the concept of four or several levels of computer room, which comes from the definition of computer room in the relevant standards. According to the importance of the industry where the computer room is located, the guarantee ability of the users to the systems in the computer room, and the economic and social loss and impact caused by the interruption of network information / loss of important data caused by the failure of site facilities, GB50174 divides the computer room into levels A, B and C from high to high, while TIA 942 divides the data center computer room into four levels: Tier I, Tier II, Tier Ⅲ and Tier Ⅳ from low to high [2]. The comparison of various characteristics of computer rooms at all levels is shown in Table 2.

In order to further understand the differences between computer rooms at all levels from the structure, according to the grading standard of TIA942 computer rooms, let's analyze the wiring structure of computer rooms at all levels, as shown in figure 2.

As can be seen from the above figure, network services must be provided by two independent operators (which can be in the same incoming room), so as to avoid system paralysis caused by the failure of a network operator; when the level of the computer room rises to level 3, two separate incoming rooms need to be built, and the other can maintain normal operation when one of the incoming rooms fails. In addition to the wiring requirements of the third-level computer room, it is recommended to add backup wiring in MDA, IDA and HDA areas. Conclusion: no matter in terms of network architecture or basic wiring, the data center is very different from the traditional building cabling. As China's banking, insurance, securities, government, telecommunications, petrochemical, power and Internet industries continue to attach importance to data centers, the market scale in this field continues to expand, which puts forward higher requirements for the quality of personnel in the cabling industry, which is lacking in the original professional and technical personnel. Article: Rosenberg Asia Pacific Electronics Co., Ltd. Chen Fengxia reference [1] China 2010 Integrated cabling Market report: integrated cabling working Group, 2011.05 [2] Zhang Yi et al. White Paper on Integrated cabling system [M]. Beijing: Tsinghua University Press, 2010 [3] China 2009-2010 Integrated cabling Market report: integrated cabling working Group, 2010.10.29

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