Some Basics About Migration to 40G Ethernet

Fiber optic links are vital for providing the bandwidth and speed needed to transmit huge amounts of data to and from a large number of sources. Recently more bandwidth is greatly needed to support the use of virtualization and improved space utilization in the data center. 2010 witnessed the ratification of 40 and 100 gigabit Ethernet (GbE) standard, since then leading switch manufacturers offered 40 GbE blades and more than 25% of data centers have implemented these next generation speeds. It is anticipated that by the end of this year, more and more data centers will follow suit. Therefore today’s article will provide an effective solution to help you migrate from current data center applications to 40/100 GbE.

10G OM3/OM4 Connectivity in the Data Center

The IEEE 802.3ae 10G standard released in 2002 included 10GBASE-SR OM3 guidance that can operate at 850nm with duplex fiber serial transmission. Even though duplex fiber implied duplex LC connectivity throughout the channel, 12F MPO terminated cables emerged as a primary choice for deployment in data-center backbone applications. The 12F MPO terminated trunk cable provided the highest fiber packing density to maximize pathway and space utilization in ducts, raceways, and patch panels. For example, 46C3447 is IBM BNT 10GBASE-SR SFP+ that operates over OM3 cable for a distance of 300m with LC duplex connector. An MPO connectorized backbone cable typically is terminated in patch panels using one of two methods that break-out the 12F MPO to six 2F duplex LC (Figure 1).

Standards From 10GbE to 40/100GbE

Similar to how transportation highways are scaled to support increased traffic with multiple lanes at the same speed, the 40 and 100 GbE standards use parallel optics, or multiple lanes of fiber transmitting at the same speed. Running 40 GbE requires 8 fibers, with 4 fibers each transmitting at 10 Gbps and 4 fibers each receiving at 10 Gbps. Running 100 GbE requires a total of 20 fibers, with 10 transmitting at 10 Gbps and 10 receiving at 10 Gbps. Both scenarios call for using high-density multi-fiber MPO style connectors.

According to IEEE 802.3ba standard, multimode optical fiber supports both 40 and 100 GbE over link lengths up to 150 meters when using OM4 optical fiber and up to 100 meters when using OM3 optical fiber. It is important to note that single-mode fiber can also be used for running 40 and 100 GbE to much greater distances using wavelength division multiplexing (WDM) for most data center applications of less than 150 meters. Copper twinax cable is also capable of supporting 40 and 100 GbE but only to distances of 7 meters. Take EX-SFP-10GE-DAC-1M as an example, it is Juniper SFP+ passive copper cable, which is ideal for 10G interconnect application for a link length of 1m.

Migration From Duplex Fiber Transmission to 40/100G Parallel Optics

Based on a MPO system, migration from 10G to 40G to 100G seems to be a simple and easy deployment. Starting with a 10G configuration, a base 12F MPO backbone cable is deployed between the 10G switches. As discussed earlier, modules or harnesses are used at the end to transition from the 12F MPO to LC duplex. These breakout configurations enable connectivity into the switch.

And when the switches migrate to 40G, the 10G module or harness is removed and should be replaced by a conversion module or conversion harness as shown in Figure 3 and Figure 4. Alternatively, an MPO adapter panel can be used. In any of these deployment options, the use of an MPO terminated jumper is needed to establish connectivity between the switches. For 100GBASE-SR4 networks all Figures 4-6 cabling is applicable.

Conclusion

To keep up with the path of future, MPO-based connectivity using OM3 and OM4 is the ideal solution for the data center, which makes the transition to 40/100G more easier and efficient. Fiberstore offers various types of 40GbE transceivers, MPO/MTP trunk cable, MPO/MTP harness cable, MPO/MTP cassette and other assemblies for your 40G network connectivity. For more information about our products, please contact us directly.

Laser-optimized Multimode Fiber – OM3 and OM4

How do I determine the type of fiber needed for my campus backbone? This is the question routinely asked by network designers. I must say, with many cabling options available in the market, it is a huge project to deploy a Gigabit Ethernet network—10GbE or 40/100GbE. As system engineers should not only decide which fiber type and the cabling infrastructure is perfect for their network, but the fiber counts. This article will briefly analyze the benefits of using laser-optimized 50µm multimode fiber in a Gigabit Ethernet application.

50µm Multimode Fibers Were Introduced 
Before the advent of Gigabit Ethernet, choosing fiber type in a network design was quite easy. Standard 62.5µm multimode fiber (OM1) was used for any application up to 2000 m and network speeds up to 622 Mbps and single-mode fiber was used for anything else. But Gigabit and 10GbE changed these rules. Laser-optimized 50µm multimode fiber (like OM3 and OM4) was developed with increased bandwidth performance for 10GbE, and the fiber performance was included in the ANSI/TIA-568 Standard. Figure 1 provides a vivid impression on 50µm and 62.5µm multimode fiber.

Why Consider 50 µm Over 62.5 µm?
The major difference between 50µm and 62.5µm multimode fiber is the bandwidth. 50µm fiber is specifically designed to produce higher bandwidth values than 62.5µm at 850 nm, which enables the fiber to be used with lower cost 850nm VCSEL transmitters. Standard 50µm fiber has three times the bandwidth of standard 62.5µm fiber in the short wavelength operating window while some of the never laser-based 50µm fiber designs have 10-20 times the bandwidth of standard 62.5µm fiber (see in Figure 2). The most commonly used 50µm fibers on the market for Gigabit Ethernet is OM3 and OM4.

OM3 and OM4 Fibers
OM3 and OM4 fibers are essential components to the success of 10G optical connectivity, which are optimized for laser-based 850nm operation and have a minimum 2000 MHz•km and 4700 MHz•km effective modal bandwidth, respectively. 10G operation is supported on OM3 to 300 m and OM4 to 550 m compared to 100 m with CAT 6A copper cable. The laser-optimized fibers provide a migration path for supporting even higher data rates such as 16G and 32G Fibre Channel and 40/100G Ethernet where CAT 6/6A has no migration beyond 10G. OM3/OM4 laser-optimized 50µm multimode fiber for 10G optical connectivity in data center enables better transmission distance and performance when comparing with OM1 and OM2 fibers. For example, GP-10GSFP-1S is compatible Dell Force10 10GBASE-SR SFP+ transceiver. It required an OM3 cable to realize the link length of 300m.

As increased bandwidth requirements are called out in new installations, which have dictated a need to transition from cost-effective multimode systems to more costly single-mode systems to solve the problem of limited transmission distance in the existing infrastructure. However, compared with the expensive single-mode cabling, OM4 effectively provides an additional layer of performance that supports these applications at longer distances, thereby limiting the number of installations that truly require OS2 single-mode fiber. OM4 can even provide a minimum reach of 125m over multimode fiber within the 40 and 100GbE standards. For example, FTL410QE2C (compatible Finisar 40GBASE-SR4 QSFP+) covers a distance of 150m over OM4 cable.

Conclusion
When determining fiber types for a network application, a couple of key points should be drawn to help make the best decision. First, use the standards of each technology, do some analysis, understand the physical topology and the logical topology, then examine where you can save money. Last but not least, for distances less than 550 m, a laser-optimized multimode fiber may yield a price savings compared to a single-mode solution. Fiberstore provides a full range of multimode fibers including OM1, OM2, OM3 and OM4 multimode fibers. We offer these cables at a minimum price but with high quality. If you have any requirement of our products, please contact us directly.