Selecting Proper Fibers for Smooth 40/100G Migration

petak , 09.12.2016.

Nowadays, there is a widespread concern over the migration from traditional 10G to 40/100G Ethernet network, which seems to be an irreversible trend. As we know, 40/100G Ethernet network can greatly address the problem of very low network speed. Do you also consider upgrading your system for higher bandwidth and larger capacity? There is no doubt that fiber cables must be the first choice for a smooth 40/100G migration, which almost makes copper cables obsolete. But which kind of fiber should be chosen? Is there any key notice should be taken into consideration when selecting fiber for the migration? These problems will be explored and answered in the following parts.

Which Fiber Type Should Be Chosen for 40/100G Migration?
It is reported that over 80% of data centers support their network within 100 meters in recent years. That’s to say, if the fiber has the ability to transmit 40/100G signal for a short distance, it almost satisfies the needs for migration. In general, there are single mode and multimode fiber available for data centers, both of which are capable of supporting 40/100G data transmission links. But which one is the most cost effective for a whole 40/100G system? Let’s talk about it and seek the answer.

For single mode fiber, it can only carry a single light signal and has little modal dispersion in the transmission process, which is highly recommended for long distance transmission. While for multimode fiber, it is able to carry several light signals in the different modes that results in serious dispersion. What’s more, the longer the signals are transmitted, the larger the dispersion will be. Hence, multimode fiber is more popularly used in short distance transmission and much more inexpensive than single mode fiber.

In short, although single mode fiber has a higher performance in data transmission, multimode fiber is more suitable for 40/100G migration as the most cost effective fiber solution.

Notices for Data Transmission Distance
There are two kinds of multimode fiber patch cables, OM3 patch cable and OM4 patch cable that allow for smooth 40/100G migrations with different transmission distances. The following figure shows some commonly used transmission cases in 10G, 40G and 100G network, both of which are able to use short--wavelength (850 nanometer) transmission over OM3 and OM4 patch cable.

From the figure, we can easily learn that both OM3 and OM4 patch cable are suitable for 10G, 40G and 100G applications. As for OM3 patch cable, it is able to support 10G network at lengths up to 300 meters and 40/100G network at lengths up to 100 meters. Compared to OM3 patch cable, OM4 patch cable can transmit signals longer under the same network, which is also a little bit expensive. In fact, its transmission distance can be 550 meters in 10G network and 150 meters in 40/100G network.

Notices for Channel Insertion Loss
It is obvious that different cables have different channel insertion loss in 40/100G network, which may have different influences on the signal transmissions. Once the channel insertion loss is high, it may cause a failed or wrong signal transmission. So that, the channel insertion loss should be also noticed when selecting fibers.

As shown in the following figure, the channel insertion loss by using OM3 patch cable is about 1.9 dB in supporting 40/100G data transmission link which is much lower than in supporting 10G link. If OM4 patch cable is selected to transmit 40/100G signals, the channel insertion loss is only 1.5dB. Undoubtedly, OM4 patch cable performs better than OM3 patch cable in this aspect.



Conclusion
Are you ready to make the 40/100G migration? If yes, you are suggested to choose multimode fiber as the most cost efficient fiber solution. According to the data transmission distance, you can choose OM3 patch cable to support 40/100G link at length up to 100 meters, which is more inexpensive than OM4 patch cable. If the distance can’t meet your requirement, you are suggest to choose OM4 patch cable with lower channel insertion loss.