The Need for Speed Drives High-Density OM3/OM4 Optical Connectivity in the Data Center

Transcription

1 The Need for Speed Drives High-Density OM3/OM4 Optical Connectivity in the Data Center Doug Coleman, Manager, Technology & Standards, Corning Cable Systems Optical connectivity with OM3/OM4 laser-optimized 50/125 μm multimode fiber has emerged as the choice media in the data center. 10GBASE-SR Ethernet is becoming the primary data rate for data centers in response to server virtualization, converged networks and the need to mitigate I/O server bottleneck. Data centers are deploying OM3/OM4 connectivity solutions to meet the 10G two-fiber serial transmission needs, as well as to provide for future migration to 40/100G parallel optics. High-port-count 10/40/100G electronics require utilization of high-density optical connectivity in the data center to facilitate ease of cable management, optimized pathway and space utilization as well as support green initiatives. The Need for Speed Server virtualization and converged networks drive the need for higher network data rates. Server virtualization increases utilization rates by integrating multiple applications on one server, as well as reducing the number of servers. The ability to support higher numbers of applications per server comes through technology enhancements in virtualization software and multicore processors (Figure 1). Where legacy servers have one application per server with typical 15 to 20 percent utilization, virtualized servers presently have the capability to support 20 to 25 applications, which can increase utilization to 80 to 90 percent. The expectation is that virtualized servers may support 100 applications in the near future. Running 25 applications on one physical server offers material and energy costs savings as it potentially eliminates 24 single application servers. Figure 1 Litcode-##-EN LAN-1382-EN Page 1

2 The increased number of applications per server generates the need for => 10G throughput. Depending on the bandwidth requirements for a server, an 8-core processor may be able to drive tens of Gb/s of bandwidth. This translates into the need for a highdata-rate network infrastructure to accommodate a much higher level of server I/O performance. Figure 2 provides a server connection speeds forecast (10G, 40G and 100G). The expectation is that 10G will have a rapid adoption in the next two years at the server and at network switches, such as the core and edge switches. Figure 2 Data centers utilize multiple networks that present operational and maintenance issues as each network requires dedicated electronics and cabling infrastructure. Ethernet and Fibre Channel are the typical networks, with Ethernet providing a local area network (LAN) between users and computing infrastructure, while Fibre Channel provides connections between servers and storage to create a storage area network (SAN). Standard activity has taken place to converge the two networks as Fibre Channel over Ethernet (FCoE). FCoE is simply a transmission method in which the Fibre Channel frame is encapsulated into an Ethernet frame at the server. The server encapsulates Fibre Channel frames into Ethernet frames before sending them over the LAN and de-encapsulates them when FCoE frames are received. The converged network makes use of low cost Ethernet electronics to transport Ethernet and Fibre Channel data. Table 1 provides the Fibre Channel Industry Association (FCIA) FCoE speed road roadmap. Where 10G FCoE utilizes serial duplex fiber transmission, 40/100G FCoE speeds will require parallel optics. FCoE Speed Roadmap Product Naming Throughput (MB/sec) Equivalent Line Rate (Gbaud) Year Tii Spec Completed Market Availability 10GFCoE GFCoE TBD Market Demand 100GFCoE TBD Market Demand Table 1 Litcode-##-EN LAN-1382-EN Page 2

3 OM3- or OM4-Preferred Fibers in the Data Center OM3 and OM4 laser-optimized 50/125μm multimode fibers are the choice fiber type for connectivity in the data center. The fibers provide a significant value proposition when compared to single-mode fiber, as multimode fiber utilizes low cost 850 nm transceivers for serial and parallel transmission. The IEEE 802.3ba 40/100G Ethernet Standard was ratified in June 2010 and specified parallel optics transmission for multimode fiber. Parallel optic transmission is specified instead of serial transmission due to 850 nm VCSEL modulation limits at the time the guidance was developed. OM3 and OM4 are the only multimode fibers included in the standard. The 40/100G standard does not have guidance for CAT UTP/STP copper cable. Figure 3 40GBASE-SR4 Parallel Optics Figure 4 100GBASE-SR10 Parallel Optics Table 2 provides the OM3- and OM4-specified distances for Ethernet and Fibre Channel. Each distance assumes 1.5 db total connector loss with the exception of OM4 40/100G, which assumes 1.0 db total connector loss. OM3 and OM4 are fully capable to support legacy and emerging data rates such that a 15- to 20-year service life is expected for the physical layer. Litcode-##-EN LAN-1382-EN Page 3

4 850 nm Ethernet Distance (m) 1G 10G 40G 100G OM OM / Proposed distance for 10G standard 2 Engineered length 850 nm Fibre Channel Distance (m) 4G 8G 16G OM Table 2 OM High-Density Optical Connectivity Network switching products are available with 48 SFP+ port line cards that use more than a 1,000 OM3/OM4 fibers per chassis switch for 10G duplex fiber serial operation. Future 40/100G switches are projected to use more than 4,000 fibers per chassis where parallel optics is deployed. Network electronics high-fiber-count requirements demand highdensity cable and hardware solutions to maximize utilization of pathway and spaces, ease cable management and simplify connections into system electronics. Bend-optimized OM3/OM4 fiber offers significantly smaller cable diameters and hardware components that yield the highest connectivity density in the data center. Compared to traditional multimode fiber, bend-optimized OM3/OM4 fiber facilitates reduced trunk cable diameters of 15 to 30 percent and hardware patch panel densities of 4,000+ fibers. The reduced trunk cable diameter consumes less pathway and space, as well as supports more efficient usage of cable trays that results in major material cost savings (Figure 5). Figure 5 Data centers need to install high-density 12-fiber MPO trunk cables with OM3/OM4 fiber today. These can be used for duplex fiber serial transmission, providing an effective migration path to parallel optics that require an MPO interface into the switch electronics and the server NIC (Figure 6). Litcode-##-EN LAN-1382-EN Page 4

5 Figure 6 High-density modular 4U and 1U hardware patch panels easily support duplex fiber serial transmission and simplify migration to parallel optics with the usage of MPO/LC modules (Figure 7). MPO/LC modules are used to break out the 12-fiber MPO connectors terminated on a trunk cable into simplex- or duplex-style connectors. Simplex- and duplex-style patch cords then can be used to patch into system equipment ports and crossconnect patch panels. The MPO/LC modules are easily removed and replaced with MPO adapter modules as needed to begin parallel optics transmission. 40G multimode fiber transmission will use a 12-fiber MPO and 100G multimode fiber transmission will use a 24-fiber MPO connector at the transceiver interface. Figure 7 Patch panels have integrated trays that contain the MPO/LC modules. Each tray has four discrete MPO/LC modules to enhance modularity for moves, adds and changes. 4U and 1U patch panels have 12 and 2 trays, respectively. A 4U housing is typically used to connect into high-density electronics, as well as for cross-connects. A 1U housing is typically used for trunk cables to interconnect into top-of-rack edge switches. Figures 8 and 9 illustrate patch panel designs, and Table 3 provides patch panel fiber capacities. Litcode-##-EN LAN-1382-EN Page 5

6 Figure 8 4U Patch Panel Figure 9 1U Patch Panel 4U Housing 10G Ports 2-fiber LC Duplex 40G Ports 12-fiber MPO 100G Ports 2 x 12-fiber MPOs 10G Ports 24-fiber MPO Circuit Capacity Fiber Capacity U Housing 10G Ports 2-fiber LC Duplex 40G Ports 12-fiber MPO 100G Ports 2 x 12-fiber MPOs 10G Ports 24-fiber MPO Circuit Capacity Fiber Capacity Table 3 Litcode-##-EN LAN-1382-EN Page 6

7 The MPO/LC harness assembly has become a popular method for connections into high-port-count network switches. An MPO connectorized trunk cable terminates with the harness assembly at the network electronics patch panel. The harness assembly has an MPO connector on one end of the cable, while the other end is equipped with simplex- or duplex-style connectors. Compared to typical two-fiber jumpers, harness assemblies significantly reduce the bulk of cabling into the electronics to facilitate ease of management, as well as enhance cooling efficiency. In addition, the harness assembly can be configured with staggered, connectorized legs that match the pitch of the electronics line card (Figure 10). When converting to parallel optics, you would simply remove the harness assembly and replace with the appropriate MPO jumper cable. Figure 10 Conclusion Existing and emerging network technologies are driving the need for increased data rates and fiber usage in the data center. High-density optical connectivity solutions are essential to address these trends to optimized cable management and data center real estate usage, as well as provide an easy migration from duplex fiber serial transmission to 12- and 24-fiber parallel optics transmission. OM3/OM4 optical connectivity solutions are well prepared to meet these challenges. Litcode-##-EN LAN-1382-EN Page 7

8 notes Corning Cable Systems LLC PO Box 489 Hickory, NC USA FAX: International: Corning Cable Systems reserves the right to improve, enhance and modify the features and specifications of Corning Cable Systems products without prior notification. LANscape and Pretium are registered trademarks of Corning Cable Systems Brands, Inc. MTP is a registered trademark of USConec, Ltd. All other trademarks are the properties of their respective owners. Corning Cable Systems is ISO 9001 certified. 2008, 2011 Corning Cable Systems. All rights reserved. Published in the USA. LAN-1382-EN / November 2011 LAN-1382-EN Page 8