MTP Connectivity — Low-loss Multifiber Connectivity

It is not difficult to understand that MTP connectivity is widely applied in 40G and 100G network applications because it is a multifiber connectivity, which can meet the demand for high-density cabling. As a matter of fact, there is another key advantage of MTP connectivity, that is low-loss. With the length and type of the fiber cable, number of connectors and splices all contributing to the link loss, there is no doubt that insertion loss is inevitable during the cabling process. Therefore, cabling solution with low-loss will be preferred by data center managers, who are now regarding optical insertion loss budgets as one of the top concerns. But what contributes to low-loss in MTP connectivity? This post will show you the answer.

Low-loss Connector

Typical MPO/MTP fiber connector, which is used for 40 and 100 GbE deployments, has insertion loss values that range from 0.3 dB to 0.5 dB. In addition, MPO/MTP connector is structured with MT ferrule which has low insertion loss and can provide accurate fiber alignment. Take 12 fiber MPO connector and 24 fiber MPO connector for example, with low-loss ferrules, the insertion loss of both two type of connectors can be rated at 0.35 dB maximum. Reading this, you may ask shouldn’t the result be that higher fiber count will lead to higher insertion loss? The answer is no. Because when using proper polishing techniques, 24-fiber MPO/MTP terminations can meet the same performance levels as 12-fiber MPO/MTP assemblies.

Low-loss Cable

We know that OM3 and OM4 fibers used in MTP connectivity utilize 850 nm source, and IEEE 40GBASE-SR4 and 100GBASE-SR10 standards for 40 and 100 GbE over multimode fiber have more stringent loss requirements for these two types of fibers, which lowers the overall channel loss. As shown in the following table, as speeds have increased from 1 Gb/s to 40 and 100 Gb/s, maximum channel distance and loss has decreased significantly. For OM3 fiber cabling, the 40 and 100 GbE standards allows for a channel distance of 100 meters with a maximum channel loss of 1.9 dB, including a maximum connector loss of 1.5 dB; for OM4 fiber cabling, the distance is increased to 150 meters but with a maximum channel loss of 1.5 dB, including a maximum connector loss of 1.0 dB.

channel loss of OM3 and OM4 fibers

Note: Current TIA and ISO standards require a minimum of OM3 fiber, while TIA recommends the use of OM4 due to its longer transmission capabilities. In fact, the 100GBASE-SR4 standard that uses eight fibers (four for transmitting and four for receiving) at 25 Gb/s is anticipated to be supported by OM4 fiber to 100 meters, but to only 70 meters using OM3.

Conclusion

In today’s large virtualized server environments with high speed 40 and 100 gigabit Ethernet (GbE) backbone switch-to-switch deployments for networking and storage area networks (SANs), staying within the loss budget is essential for ensuring that optical data signals can be properly transmitted from one switch to another without high bit error rates and performance degradation. MTP connectivity, based on low-loss MPO/MTP connector, OM3 and OM4 fibers, is able to reduce the insertion loss to a minimum, which makes this low-loss multifiber connectivity take its place on the market. FS.COM provides high-quality MTP assemblies, such as MTP/MPO fanout cable, MTP MPO trunk cable, MTP cassette and so on. If you want to know more details, please visit our site.

Why Short Distance MTP-based Connectivity Utilizes OM3 or OM4 Fibers?

As today’s network needs to support more devices and advanced applications than ever before, the amount of data transmitted at the enterprise business level is rapidly climbing. For many data centers, 10G network no long satisfies the need of high speed data transmission. In 2010, the IEEE ratified the 40G ad 100G standard. Then how to realize smooth migration path from 10G to 40G and 100G has become the most concern for data center managers. After some comparison, many data center managers turn to MTP-based connectivity since it can provide fast installation, high density and high performance cabling for data centers. It is not difficult to find that both MTP/MPO trunk cable and MTP/MPO breakout cable (shown as the figure below) used for short distance connectivity utilize OM3 or OM4 fibers. Why short distance MTP-based connectivity utilizes OM3 or OM4 fibers? This article will show you the reason.

MTP MPO trunk cable and MTP MPO breakout cable

Bandwidth

OM3 and OM4 fibers are the only multimode fibers included in the 40/100G standard. Multimode fibers utilize parallel optical transmission instead of serial transmission due to the 850 nm VCSEL (vertical cavity surface emitting laser) modulation limits. And OM3 and OM4 fibers have a minimum 2000 MHz∙km and 4700 MHz∙km effective modal bandwidth (EMB). The minimum EMBc (Effective Modal Bandwidth calculate) method measures the actual fiber bandwidth performance, recognizing the fact that overall system bandwidth is a function of both the bandwidth properties of the fiber and also the particle characteristics of individual laser sources, and this is the most significant factor in determining link performance. In addition, the IEEE model is the industry reference point for calculating the maximum achievable Ethernet link distance and sets out the minimum requirements of components in an optical link. Therefore, knowing the exact minimum bandwidth performance of OM3 and OM4 fibers is a prerequisite to understand the ultimate limitation of MTP-based connectivity, which can ensure the optical infrastructure deployed in the data center will meet the performance criteria set forth by IEEE for bandwidth.

Insertion Loss

No matter what kind of cabling system you are going to deploy, insertion loss is inevitable and it is an essential performance parameter of the network deployment. It is important to note that the total connectivity loss within a cabling system has an effect on the network performance over the maximum link distance at a given data transmission rate. It is not difficult to understand that the higher the total connectivity loss, the shorter the maximum link distance. As a result, the insertion loss specifications of components used for connectivity should be evaluated at first when designing data center cabling infrastructures. The 40G standard specifies that with link distance up to 100 meters, the maximum channel loss of OM3 fiber is 1.9 dB, which includes a 1.5 dB total connectivity loss budget; while for OM4 fiber, it is specified that with link distance up to 150 meters, the maximum channel loss is 1.5 dB, which includes a 1.0 dB total connectivity loss budget. And the maximum attenuation of fiber optic cable at 850 nm is 3.5 dB/km. With low-loss OM3 and OM4 fibers, maximum flexibility can be achieved with the ability to utilize MTP connector in the optical link.

Conclusion

With 850nm EMB of 2000 MHz∙km and 4700 MHz∙km, OM3 and OM4 fibers can provide the bandwidth which is needed in MTP-based connectivity for 40G network. Besides, low-loss within cabling system is another characteristic of OM3 and OM4 fibers, which can ensure the high performance of the network deployment. Therefore, utilizing OM3 and OM4 fibers makes short distance MTP-based connectivity an ideal solution for migration from 10G to 40G in data centers.