Comparison Between Singlemode QSFP28 and Multimode QSFP28

Fiber optic transceiver, as an important optical component, is widely used for transmitting and receiving optical signals to facilitate communication. To meet the increasing demand for higher speed and bandwidth, fiber optic transceiver has continued to evolve, from SFP, 10G SFP+, 40G QSFP+ to 100G CFP and QSFP28. Among them, 100G QSFP28 transceiver is now very popular on the market. We know that fiber optic transceiver can be divided into singlemode transceiver and multimode transceiver, so this article will make a comparison between singlemode QSFP28 and multimode QSFP28.

Singlemode QSFP28

Singlemode QSFP28 is usually used with singlemode fiber. We know that the core of singlemode fiber is smaller and the laser wavelength is narrower. Therefore, singlemode fiber permits the transmission of signals at higher bandwidth thus facilitating the data transmission at a longer distance. Singlemode QSFP28 mainly works at 1310nm wavelength and is commonly used for long distance data transmission. There are different types of singlemode QSFP28 which can achieve different data transmission distance, such as 100GBASE-PSM4 QSFP28 can support 500 meters, 100GBASE-CWDM4 QSFP28 can support 2 kilometers and 100GBASE-LR4 QSFP28 can support 10 kilometers. And there are some other differences among them. The 100GBASE-PSM4 QSFP28 is designed with 12-fiber MTP connector interface, so it is used with MTP cable; while 100GBASE-CWDM4 QSFP28 and 100GBASE-LR4 QSFP28 are structured with duplex LC connector interface, so they are used with duplex LC patch cable.

singlemode QSFP28 and singlemode fiber

Multimode QSFP28

Multimode QSFP28 is usually used with multimode fiber. The core of multimode fiber is much bigger and multimode fiber usually uses a wider wavelength of light. In addition, it permits the use of inexpensive LED light sources and alignment of the connectors with a coupling that is less critical than that of singlemode fiber. As a result, fiber optics used over multimode fiber have a higher capability to gather light from the laser and are cheaper. Multimode QSFP28 mostly works at 850nm wavelength and is used for short optical link length, like 70 meters over OM3 and 100 meters over OM4. There is only one type of multimode QSFP28—100GBASE-SR4 QSFP28. It has 12-fiber MTP connector interface, so it has to be used with MTP cable.

100GBASE-SR4 QSFP28

Comparison Between Singlemode QSFP28 and Multimode QSFP28

From the above, we can clearly see some differences between singlemode QSFP28 and multimode QSFP28. This part will make a summary from several aspects.

Transmission media: Singlemode QSFP28 works with singlemode fiber while multimode QSFP28 works with multimode fiber. It is noted that 100GBASE-PSM4 QSFP28 is used with singleomde MTP cable and 100GBASE-SR4 QSFP28 is used with multimode MTP cable; while 100GBASE-CWDM4 QSFP28 and 100GBASE-LR4 QSFP28 are used with singlemode duplex LC patch cable.

Transmission distance: Singlemode QSFP28 can reach 500 meters, 2 kilometers and 10 kilometers while multimode QSFP28 is able to support 100 meters optical link.

Power consumption: Multimode QSFP28 consumes less power than singlemode QSFP28, which is an important consideration especially when assessing the cost of powering and cooling a data center.

Cost: Singlemode QSFP28 are nearly two or three times higher in price when compared to multimode QSFP28. Because singlemode fiber requires more expensive laser sources and costs more to make as it is more “fragile”.

Compatibility issue: When it comes to issues dealing with compatibility, the two types of QSFP28 transceivers are not compatible due to the differences in fiber core size and wavelengths.

Conclusion

This article makes a comparison between singlemode QSFP28 and multimode QSFP28. Both of them have their own advantages in data center applications. As for which one to choose, it all depends on your specific requirement of deployment. FS.COM, as a professional optical products supplier, offers various QSFP28 optics to meet customers’ diverse needs. If you have any need, please visit www.fs.com for more detailed information.

Cabling Solutions for 100G CFP/120G CXP

The step for higher capacity and throughput in data centers has never stopped and the 100G/120G Ethernet network has been widely applied. However, it is not an easy job to upgrade existing 10G/40G equipment to meet the requirement of 100G/120G Ethernet network. Is there any cabling solution for smooth migration from 10G/40G to 100G/120G? Of course, there is. This article will take multimode 100G CFP/120G CXP transceiver for example and introduce some cabling solutions to you.

100G/120G to 100G/120G

We know that 100G CFP/120G CXP transceiver is designed with 24 fiber MTP/MPO connector interface (10 Tx and 10 Rx with each lane providing 10Gbps, leaving 4 channels unused). Therefore, it is usually used with 24 fiber MTP/MPO cable. The following figure shows that two 100G CFP/120G CXP transceivers are separately plugged into 100G port on two 100G switches. And then the two 100G CFP/120G CXP transceivers can be directly connected by a 24 fiber MTP/MPO trunk cable. This the simplest cabling solution for 100G/120G to 100G/120G connectivity.

100G 120G to 100G 120G

100G/120G to 10G

By using the 24 fiber MPO to 12 LC duplex harness cable, the 100G/120G to 10G connection can be achieved. However, for the optical link completed by 100G CFP transceiver and ten SFP+ transceivers, there are two LC duplex legs are not used; for 120G to 10G connection, one 120G CXP transceiver and twelve 10G SFP+ transceivers are connected which realize 100% fiber utilization. In this cabling solution, three 10G switch may be needed to satisfied the requirement of at least twelve 10G SFP+ ports. As the following figures shows, 100G CFP/120G CXP transceiver is plugged into 100G port on 100G switch on one side, while ten or twelve 10G SFP+ transceivers are plugged into 10G ports on 10G switches on the other side. Then the 100G CFP/120G CXP transceiver and ten or twelve 10G SFP+ transceivers can be connected by the 24 fiber MPO to 12 LC duplex harness cable. This is also the simplest cabling solution for 100G/120G to 10G connectivity.

100G 120G to 10G

With the use of MTP/MPO fiber optic patch panel, 100G to 10G connection can also be reachable. From the figure below we can see that one end of 24 fiber MTP/MPO trunk cable is plugged into 100G CFP transceiver on the 100G switch, while the other end is plugged into MTP ports on the rear of the MTP/MPO fiber optic patch panel. Then the one end of ten LC duplex patch cables are plugged into the LC ports on the front of the MTP/MPO fiber optic patch panel and the other end of cables are connected with ten 10G SFP+ transceivers which are plugged into 10G ports on 10G switches. This cabling solution offers ultimate flexibility in allowing connectivity to any row, rack or shelf. In addition, the MTP/MPO fiber optic patch panel can support up to eight groups of this 100G to 10x10G transmission.

100G to 10G

There is a hybrid link for 120G CXP transceiver, 40G QSFP+ transceiver and 10G SFP+ transceiver. We can use the 1×3 MTP/MPO conversion harness cable to connect 120G CXP transceiver on 100G switch and three 40G QSFP+ transceivers on 40G switches. Then another three 40G QSFP+ transceivers on the 40G switches can be connected with the twelve 10G SFP+ transceivers on 10G switches by three 12fiber MTP-LC fanout cables.

120G to 40G to 10G

Conclusion

As 100G/120G Ethernet network has becomes more and more popular, various types of 100G CFP/120G CXP transceivers are available on the market. This article has illustrated some cabling solutions for migration from 10G/40G to 100G/120G and it is not difficult to find that MTP components are commonly used in these cabling solutions. I hope after reading this article, you can learn something useful.

Overview of 100G Transceivers

There was a time when 10G to 40G migration was a hot spot, and as the only available 40G transceiver, 40G QSFP+ has occupied the major position in the market. However, the pace of development has never stopped and the demand for higher speed data transmission keeps growing. And now, many data center managers set their sight on 100G Ethernet. As an important component in 100G optical links, 100G transceivers gradually gain great popularity among data center managers. But unlike 40G transceiver, 100G transceiver has several types, such as CFP/CFP2/CFP4, CXP and QSFP28. How much do you know about them? This article is going to give an overview of 100G transceivers.

CFP/CFP2/CFP4

The letter “C” in CFP/CFP2/CFP4 stands for 100. The CFP transceiver is specified by MSA between competing manufacturers and it can support 100Gbps over both single-mode and multimode fiber. The electrical connection of a CFP uses 10 x 10G lanes in each direction (RX, TX) while the optical connection can support both 10 x 10G and 4 x 25G variants of 100G interconnects. With improvement in higher performance and higher density, CFP2 and CFP4 appeared. While electrical similar, they specify a form factor of 1/2 and 1/4 respectively in size of CFP. CFP, CFP2 and CFP4 modules are not interchangeable, but would be inter-operable at the optical interface with appropriate connectors.

CFP-CFP2-CFP4

Here is a table for you which shows five typical transceiver types. We can get that CFP-SR10-100G is structured with 24-fiber MTP connector interface, so it can be used with multimode MTP 24 to MTP 24 100g trunk cable to support 100G optical links over short distance; designed with LC duplex interface, CFP-LR4-100G, CFP-ER4-100G, CFP2-LR4-100G and CFP4-LR4-100G are used with LC duplex patch cable to support 100Gbps data rate over long distance.

CFP CFP2 CFP4 transceiver information

CXP

The CXP was created to satisfy the high-density requirements of the data center, targeting parallel interconnections for 12x QDR InfiniBand (120G), 100G, and proprietary links between systems collocated in the same facility. The CXP is 45 mm in length and 27 mm in width, making it slightly larger than an XFP. It includes 12 transmit and 12 receive channels in its compact package. This is achieved via a connector configuration similar to that of the CFP.

QSFP28

Similar to 40G QSFP+, 100G QSFP28 also offers four independent transmit and receiver channels, but each channel is capable of 25Gbps data rate for an aggregate data rate for 100Gbps. With an upgraded electrical interface to support signaling up to 25Gbps signals, the 100G QSFP28 makes it as easy to deploy 100G network as 10G networks. When compared to any of the other alternatives, the 100G QSFP28 increases density and decreases power and price per bit, but It has to noted that 100G QSFP28 has the same physical size as 40G QSFP+. Just like 40G QSFP+, 100G QSFP28 can be both deployed for short data transmission distance over multimode fiber and long data transmission distance over single mode fiber. For example, 100GBASE-PSM4 QSFP28 can be used with MTP single mode cable to support 100G data rate with link length up to 500 meters.

100G QSFP28 transceiveres

Conclusion

Now is the time of 100G Ethernet and 100G transceivers are indispensable to complete the 100G optical links. As there are various types of 100G transceivers available on the market, it is necessary to choose the best suitable one for your network deployment. As a professional manufacturer and supplier in optical communication industry, FS.COM provides a complete range of 100G transceivers to meet the potential requirements. The prices of all our 100G transceivers are much more affordable than the similar products in the market. Furthermore, with the mature coding technology, they can be compatible with many major brands. For more details, please visit our site.