Migrating to 40/100G Era with OM3 and OM4

To meet the continuously increased requirements, data center 40/100G migration is underway. The infrastructure of data centers for the 40G/100G should meet the requirements like high speed, reliability, manageability and flexibility. Fiber optic patch cable plays an important part. The cable used in data center must be selected to provide support for the higher needs of data rate. OM3 and OM4 fiber patch cables have gradually become the popular choice of data center during 40/100G migration. This article illustrates OM3/OM4 multimode fiber cables in 40/100G migration in details.

Why Choose OM3 and OM4 in 40/100G Migration?

OM stands for optical multimode. Why not single-mode fiber cables? The answer is the cost. The price of single-mode fiber is generally more expensive than multimode fiber. Multimode fiber utilizes low cost 850nm transceivers for serial and parallel transmission. Why not OM1 or OM2? Compared with OM1 and OM2, OM3 and OM4 can transport data at higher rate and longer distance. OM3 and OM4 are both laser-optimized multimode fibers with 50/125 core, which are designed for use with 850nm vertical-cavity surface-emitting laser (VCSEL) and are developed to accommodate faster networks such as 10, 40 and 100 Gbps. The IEEE 802.3ba 40/100G Ethernet Standard provides specific guidance for 40/100G transmission with multimode and single-mode fibers. OM3 and OM4 are the only multimode fibers included in the standard. The reason why OM3 and OM4 are applied in 40/100G migration is that they can meet the requirements for the migration cabling performance.

Advantages of Utilizing OM3 and OM4

Bandwidth, transmission distance and total connector insertion loss are three main factors should be considered when evaluation the performance needed for cabling infrastructure to meet the requirements for 40/100G. Advantages of utilizing OM3 and OM4 in these three aspects will be explained below.

Higher Bandwidth: OM3 and OM4 are optimized for 850nm transmission and have a minimum 2000MHz∙km and 4700MHz∙km effective modal bandwidth (EMB). Comparing the OM1 and OM2 with a maximum of 500 MHz∙km, advantages of OM3 and OM4 are obvious.

Longer Transmission Distance: OM3 fiber and OM4 fiber can support longer transmission distance compare with other traditional multimode fibers. Generally OM3 fibers can run 40/100 Gigabit at 100 meters and OM4 fibers can run 40/100 Gigabit at 150 meters. This high data rate and longer distance cannot be achieved by other traditional multimode fiber like OM1 and OM2.

Lower Insertion Loss: According to the 40/100G standard, OM3 fiber is specified to a 100m distance with a maximum channel loss of 1.9dB, which includes a 1.5dB total connector loss budget. And OM4 fiber is specified to a 150m distance with a maximum channel loss of 1.5 dB, including a total connector loss budget of 1.0 dB. With low-loss OM3 and OM4 fiber, maximum flexibility can be achieved with the ability to introduce multiple connector mating into the connectivity link and longer supportable transmission distance can be reached.

OM3 or OM4?

OM3 and OM4 are both available for 40/100G applications. But you also need to choose which one to use. The applications and the total costs are always the main factors to consider to figure out whether OM3 or OM4 is needed. The connectors and the termination of the connectors for OM3 and OM4 fibers are the same. OM3 is fully compatible with OM4. The difference is just in the construction of fiber cable, which makes OM4 cable has better attenuation and can operate higher bandwidth at a longer distance than OM3. Thus, the cost for OM4 fiber is higher than OM3. As 90 percent of all data centers have their runs under 100 meters, choosing OM3 comes down to a costing issue. However, looking in the future, as the demand increases, the cost will come down. Thus, OM4 might be the most viable product at some point soon.

Conclusion

Migration to 40/100G has already been underway. With good performance like high data rate, long transmission distance and lower inserting loss, it seems that OM3/OM4 fiber cable is a must in data center migration to 40/100G.