Know More About 100GBASE-PSM4 QSFP28 Transceiver

There is an interesting phenomenon that multimode fibers are more expensive than single-mode fibers but the transceivers are the reverse. That is because the multimode core diameter is large and easy to align with VCSEL lasers and detectors while the single mode fiber cable is very hard to build and align transceiver components with and requires very expensive alignment equipment. Therefore, multi-mode transceivers are less expensive than single-mode transceivers. Now the 100G Ethernet network has been widely applied in data centers and there are various types of 100G fiber optic transceivers available on the market. Is there a type of 100G single-mode transceiver which can provide a low-cost solution for long-reach data center optical interconnects? The answer is Yes. The 100GBASE-PSM4 (parallel single-mode 4-lane) QSFP28 transceiver can do that.

Overview of 100GBASE-PSM4 QSFP28 Transceiver

The 100GBASE-PSM4 QSFP28 transceiver supports 100G link over eight single-mode fibers (four fibers for transmit and four fibers for receive) with data transmission distance up to 500 meters. It uses four parallel lanes for each signal direction and each lane carries 25G optical signal. In addition, the 100GBASE-PSM4 QSFP28 transceiver is structured with MTP/MPO interface, so it is usually used with single-mode fiber ribbon cable with MTP/MPO connector.

100GBASE-PSM4 QSFP28 transceiver
Working Principle of 100GBASE-PSM4 QSFP28 Transceiver

The figure below shows the working principle of the 100GBASE-PSM4 QSFP28 transceiver. The transmitter side accepts electrical input signals compatible with common mode logic (CML) levels, wile the receiver side converts parallel optical input signals via a photo detector array into parallel electrical output signals. The receiver module outputs electrical signals are also voltage compatible with CML levels. All data signals are differential and support a data rate up to 25Gbps per channel.

working principle of 100GBASE-PSM4 QSFP28 transceiver
Applications of 100GBASE-PSM4 QSFP28 Transceiver

The 100GBASE-PSM4 QSFP28 transceiver can be used for 100G to 100G connection. As the following figure shows, two 100GBASE-PSM4 QSFP28 transceivers are plugged into Host IC, then these two transceivers are connected by MTP/MPO patch cord and MTP/MPO patch panel.

100G to 100G connection with 100GBASE-PSM4 QSFP28 transceiver

From an optical transceiver module structure viewpoint, PSM uses a single uncooled CW laser which splits its output power into four integrated silicon modulators. Therefore, the 100GBASE-PSM4 QSFP28 transceiver can be used for 100G to 4x25G connection. As the following figure shows, the 100GBASE-PSM4 QSFP28 transceiver and four 25G-LR SFP28 transceivers are connected by MTP-LC breakout cable.

100G to 4×25G connection with 100GBASE-PSM4 QSFP28 transceiver
Conclusion

The 100GBASE-PSM4 QSFP28 transceiver meets the requirement for low-cost 100G connections at reaches of 500 meters in applications that fall in between the IEEE multi-wavelength 10 kilometers 100GBASE-LR4 single-mode fiber approach and its multimode-fiber based 100GBASE-SR10 short reach specifications. It can support a link length of 500 meters over single mode fiber cable, which is sufficient for data center interconnect applications. FS.COM provides high quality 100GBASE-PSM4 QSFP28 transceiver which has been tested on corresponding equipment before shipping. If you need to buy 100GBASE-PSM4 QSFP28 transceiver, FS.COM is a great option.

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Three Cabling Solutions for 40G Network

Network technology has been developed rapidly and many data centers are utilizing 40G network to satisfy their needs for high density cabling and high speed data transmission. When it comes to 40G network cabling solutions, MPO fiber optic cable assemblies are most used by data center managers. This article is going to introduce three cabling solutions for 40G network—cabling with no conversion component, cabling with conversion module and cabling with conversion harness.

Cabling With No Conversion Component

For cabling with no conversion component solution, in fact, it is a Base-12 MTP connectivity solution. The 12-fiber MTP trunk cables are deployed in the whole 40G connectivity. But in this cabling solution, four fibers are not used. Apart from this, there will be additional cost associated with the purchase of additional fibers. Though this solution does notuse 33% of the installed fiber and may require more cable raceway congestion, it does have the advantage of simplicity and lowest link attenuation.

Cabling With Conversion Module

With the use of conversion module MPO patch panel, the unused fibers can be converted into usable fiber links. For every two 12-fiber MTP connectors in the backbone cable, we can create three 8-fiber links. Using Base-12 connectivity and Base-8 connectivity together realizes 100% fiber utilization. When reusing existing deployed MTP cabling, great value will be gained if using conversion module to use all previously deployed fibers, and we can eliminate the cost of having to deploy additional cabling.

canling with conversion module to convert two 12-fiber links into three 8-fiber links

Cabling With Conversion Harness

The cabling with conversion harness solution uses standard MPO patch panel and 2×3 MPO conversion harness. It can achieve full fiber utilization. Although it seems attractive, it involves considerable cabling challenges. For instance, if you only need two 40G connections to the equipment, what do you do with the third 8-fiber MTP connection? Or what if the 40G ports are in different chassis blades or completely different chassis switches? The result will be long assemblies, which will be difficult to manage in an organized way. For this reason, this kind of solution is expected to be the least desirable and so the least deployed method.

cabling with conversion harness to convert two 12-fiber links into three 8-fiber links

Which One to Choose?

If you are installing new cabling, then you can consider cabling with no conversion component solution, assuming that the cable raceway is not a concern. If you are using previously installed MTP trunks, cabling with conversion module solution is recommended which can realize 100% fiber utilization while maintaining any port to any port patching. The cabling with conversion harness solution is typically deployed only in specific applications, such as at the ToR switch, where 40G ports are in a close cluster and patching between blades in a chassis switch is not required.

Conclusion

It is not difficult to find that each type of cabling solution has their own advantages and disadvantages. As for which on to choose, it all depends on your specific network deployment environment and requirements. After reading the content above, I hope you can have a better understanding of these three cabling solutions for 40G network and choose a suitable cabling solution for your network deployment.