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.

Design Consideration for 40G Ethernet Network

With the speed in the data center now increases from 10G to 40G, different optical technology and cabling are required. But at first we should figure out the design of 40G Ethernet network. There are several key factors that may affect the transition to 40G. This article today will pay special attention to those aspects that influence data center design consideration.

General Data Center Design
The principal goals in data center design are flexibility and scalability, which involve site location, building selection, floor layout, electrical system design, mechanical design and modularity. Furthermore the key to a successful data center facility: one that is sustainable in the long term; the other is to consider it as a receptacle for equipment and operations, as well as an integrated system, in which each component must be considered to be flexible and scalable. Figure 1 shows a typical data center infrastructure design utilizing preterminated optical solutions.

What Does MPO Connector Means for 40G Data Center?
While speeds have increased to 40G, optical connectivity has remained in a duplex format, whether SC or LC. With the advent of 40G/100G Ethernet, multi-fiber push-on (MPO) connector technology are now used at the electronics interface and further into the data center infrastructure design. MPO technology has displayed proven value in cassette-based data center physical layer installations.

The MPO is defined by TIA-604-5-C, Fiber Optic Connector Intermateability Standard. Type MPO (FOCIS-5) as an array connector that can support up to 72 optical fiber connections in a single connection and ferrule. While the MPO is versatile in the fiber count supported, the 12-fiber MPO is the version widely deployed. Many data center designs today use cassette-based duplex LC connectivity or MPO to duplex LC harnesses at the electronics interface, while 12-fiber MPO-based connectivity is used to connect the trunk cabling to each cassette or harness.

40G Standard Provision
The Habtoor STFA Soil Group (HSSG) has designated 40G to support high-performance computing clusters, blade servers, SANs and network-attached storage. For 40G deployment, the QSFP transceiver will utilize a 12-fiber MPO. Deployment of 40G over multi-mode fiber will be achieved with 4-Tx and 4-Rx fibers from the 12-fiber MPO (see in Figure 2). Each of these four “channels” will transmit 10G for the combined 40G transmission. Single-mode fiber transmission will remain duplex connectivity using course wavelength division multiplexing. The HSSG has also defined the transmission media for 40G to include:

• 40GBASE-SR4 (parallel optics)

100m on OM3/125m on OM4—10G on four fibers per direction

• 40GBASE-LR4(cWDM)

10km on single-mode fiber—4x10G 1300nm wavelength region

• 40GBASE-CR4

7m over copper—4x10G (twinax copper)

• 40GBASE-FR(Serial)

2km on single-mode—4x10G 1550nm

As noted above, the QSFP+ module is specified for use with different standard. The 40GBASE-SR4 is terminated with the MPO connector. For example, Cisco QSFP-40G-SR4 QSFP+ transceiver enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber female connectors.

For 12-fiber MPO cassette-based optical systems already installed, 40G migration is as simple as removing the existing cassette from the patch panel housings at the equipment and cross connects and replacing the cassette with an MPO adapter panel. Next, an appropriate 12-fiber MPO jumper would be used to cross-connect the trunk cabling as well as interconnect into the QSFP. Though not widely available currently, future preterminated system trunks may utilize 24-fiber MPO connections, both on the trunks and on the cassette. In this case, 40G deployment would require an interconnect harness terminated with two 12-fiber MPO connectors at the QSFP end, and one 24-fiber MPO at the trunk end. This would provide the needed interface with the 24-fiber MPO-based trunk and the 40G QSFP. A 24-fiber MPO jumper would be needed at the system cross connects to ensure polarity was maintained and that skew was within requirements.

Conclusion
The data center infrastructure must be reliable, manageable, flexible and scalable no matter who you are asking for requirements of data center design. It is the responsibility of the network designers to insure best compatibility of data center. As migrating to 40G, we have 40G QSFP and cables within MPO connectivity. Fiberstore supplies a variety of 40G QSFP modules and cables for you to choose from. Besides QSFP-40G-SR4, QSFP-40G-SR4-S and Cisco QSFP-40G-CSR4 are also available. If you are interested in our products, please contact us directly.