Applying Standards in Data Center Network Design


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Applying Standards in Data Center Network Design

  1. 1. DATA CENTER TECHNOLOGY Applying Standards in Data Center Network Design By David Kozischek W hen designing a data cen- ogy advancements in system equipment DATA CENTER SPACES AND ter, several factors should must be considered. INFRASTRUCTURE be taken into consideration, TIA-942, Telecommunications The main elements of a data center, including standards compliance. TIA- Infrastructure Standard for Data Centers, defined by TIA-942, are: 942, Telecommunications Infrastructure was released in April 2005. The pur- Entrance room (ER): The space Standard for Data Centers, details several pose of this standard is to provide used for the interface between data of the factors that should be considered information on the factors that should center structured cabling system and when designing a data center. When be considered when planning and pre- inter-building cabling, both access implementing a structured cabling solu- paring the installation of a data center provider- and customer-owned. The tion, the standard recommends a star or computer room. TIA-942 combines ER interfaces with the computer room topology architecture to achieve maxi- within a single document all the infor- through the MDA. mum network flexibility. TIA-942 outlines mation specific to data center applica- additional factors crucial to data cen- tions. This standard defines the tele- Main distribution area (MDA): ter design, including recognized media, communications spaces, infrastructure Includes the main cross-connect, cable types, recommended distances, components and requirements for each which is the central point of distribu- pathway and space considerations, and within the data center. Additionally, the tion for the data center structured redundancy. In addition to standards standard includes guidance as to rec- cabling system and may include a hor- compliance, the need for infrastructure ommended topologies, cabling dis- izontal cross-connect when equipment flexibility to accommodate future moves, tances, building infrastructure require- areas are directly served from the adds and changes due to growth, new ments, labeling and administration, MDA. Every data center shall include applications, data rates and technol- and redundancy. at least one MDA. PAGE 8 SEPTEMBER 2009
  2. 2. DATA CENTER TECHNOLOGY Applying Standards in Data Center Network Design Figure 1 Horizontal distribution area – Outlet in the EDA channel distance allowed is 100 m, assum- (HDA): Serves equipment areas. ing 5 m of patch cord at each end of the In a data center including HDAs, the maximum distance allowed for horizontal channel for connection to end equipment. Equipment distribution area cabling is 90 m, independent of media When a ZDA is used, horizontal cabling (EDA): Is allocated for end equipment type. With patch cords, the maximum distances for copper may need to be and shall not serve the purposes of an reduced (Figure 1). ER, MDA or HAD. Telecommunications room (TR): Figure 2 R educ ed Data C enter T opology Supports cabling to areas outside the Ac c es s computer room and shall meet the specifi- P roviders cations of ANSI/TIA569B. The components of the cabling infra- C omputer structure, as defined by TIA-942, are as O c es , Ops . Main Dis tribution Area R oom C enter, S upport (R outers , B ackbone follows: R ooms LAN/S AN S witches , P B X, M13 Muxes ) – Horizontal cabling – Backbone cabling – Cross-connect in the ER or MDA – Main cross-connect in the MDA Zone Dis t Area – Horizontal cross-connect in Horizontal the TR, HDA, MDA C abling – Zone outlet or consolidation E quip Dis t Area E quip Dis t Area (R ack/C abinet) (R ack/C abinet) point in the ZDA PAGE 10 SEPTEMBER 2009
  3. 3. Applying Standards in Data Center Network Design DATA CENTER TECHNOLOGY Depending on the type and size of Figure 3 the data center, the HDA may be collapsed back to the MDA. This is a typical design for enterprise data centers. In this scenario, the cabling from the MDA to the EDA, with or without a ZDA, is considered horizontal cabling. In a collapsed design, horizontal cabling is limited to 300 m for optical fiber and 90 m for copper (Figure 2). LOGICAL TOPOLOGIES FOR DATA CENTERS While standards help guide the data center physical infrastructure, the logical data center infrastructure does not have a standards body helping with design. Logical architectures, as shown in Figure 3, vary based on customer preference and are also guided by the electronics manu- facturers. Though a standard does not exist, there are some common architecture best prac- tices that can be followed. Most logical architectures can be broken into four layers: Core segments are needed: MAPPING LOGICAL ARCHITECTURES Front-end Segment – This area con- TO TIA-942 Aggregation tains web servers, DNS servers, FTP and The key for many data center design- Access other business application servers ers is how to translate the many logical Storage Application Segment – Provides the topologies onto a TIA-942 structured cabling connection between the front-end servers infrastructure. This translation will affect some Core and the back-end servers. of the key design elements of a structured The core layer provides the high- Back-end Segment – Provides con- cabling solution such as fiber counts, hard- speed connectivity between the data cen- nectivity to the database servers. This seg- ter and the campus network. This is typi- ware considerations and physical cable runs. ment also provides access to the storage cally the area where multiple ISPs provide The first step is to translate the TIA-942 areas area network (SAN) connections to the Internet. (MDA, HDA, ZDA, EDA) to the logical archi- Storage tecture areas (core, aggregation, access, Aggregation The storage layer contains the Fiber storage). Figure 4 shows a comparison The aggregation layer provides a point Channel director and other storage devic- between the two. where all server area devices can share com- es such as magnetic disc media or tape. The next step is to take an example mon applications such as firewalls, cache engines, load balancers and other value- Figure 4 added services. The aggregation layer must be able to support multiple 10G and 1G TIA-942 Physical Logical Architecture Architecture Area Area connections to support a high-speed switch- MDA=Main Distribution ing fabric. Maps to Core and Aggregation Area Access HDA=Horizontal Maps to Aggregation The access layer provides the Distribution Area connectivity between the aggregation ZDA=Zone Distribution layer shared services and the server farm. Area Maps to Access and Storage Since additional segmentation may be EDA=Equip Distribution required in the access area, three different area Blog at SEPTEMBER 2009 PAGE 11
  4. 4. DATA CENTER TECHNOLOGY Applying Standards in Data Center Network Design logical architecture and translate it to a Figure 5 TIA-942 structured cabling solution. In this example, we will use a small data center and map the logical architecture shown in Figure 5 to the physical architecture of the data center (racks and cabinets) shown in Figure 6. The next step is to choose the TIA-942 architecture that will best map to the logical architecture shown in Figure 5. Since this data center is small, a reduced TIA-942 architecture will be implemented. In this architecture, an MDA, ZDA and EDA will be implemented. In implementing this structured cabling design, the datacenter will be seg- mented based on the logical topology shown in Figure 5. The segmentation will be as follows: 1. Collapse the core switching LAN, SAN and aggregation switching in the MDA 2. Segment the access layer into three zones: front-end, application and back-end Figure 7 PAGE 12 SEPTEMBER 2009
  5. 5. Applying Standards in Data Center Network Design INSTALLATION Figure 6 a hardware and cabling infrastructure. The TIA-942 Structured Cabling Standard provides guidance in how to properly map any logical architecture into a physi- cal architecture. When applied correctly, the structured cabling system installed today will serve the needs of the data center now and in the future. With more than 15 years of experience in communications technology, David Kozischek 3. Segment the storage into a ZDAs will homerun back to the MDA, currently serves as market manager, Data separate zone where they will terminate in a main cross- Centers for Corning Cable Systems. Kozischek Each zone will use a middle-of-the- connect (MC). This is shown in Figure 7. joined Corning Cable Systems in 1990 and has rack interconnect solution for the cabling. CONCLUSION held positions in Engineering Services as a senior Within each zone, the EDAs will utilize a When designing a data center, there field engineer and senior systems engineer; top-of-the-rack interconnect. The EDAs will be many different types of logical Strategic Planning and Business Development as will serve the electronics in each cabinet architectures to choose from. These logi- technology manager; and Global Strategic Growth and the ZDAs will serve the EDAs. The cal architectures will be deployed over as a technology discovery manager. Blog at SEPTEMBER 2009 PAGE 13