Category Archives: 40/100GbE Solutions

Cabling Solutions for 100G QSFP28 Transceiver

Since the demand for high speed data transmission keeps growing, 100G Ethernet has been widely deployed in data center. Designed for high port density with small compact size and low power consumption, 100G QSFP28 transceivers domain the 100G transceiver module market. In the previous post “Focus on 100G QSFP28 Transceiver”, I have introduced four 100G QSFP28 transceiver types—100GBASE-SR4 QSFP28 transceiver, 100GBASE-PSM4 QSFP28 transceiver, 100GBASE-CWDM4 QSFP28 transceiver and 100GBASE-LR4 QSFP28 transceiver. So in this article, I will share cabling solutions for 100G QSFP28 transceiver with you.

We know that the above four 100G QSFP28 transceiver types can be divided into two categories according to the interface: 100GBASE-SR4 QSFP28 and 100GBASE-PSM4 QSFP28 are with MTP/MPO interface, while 100GBASE-CWDM4 QSFP28 and 100GBASE-LR4 QSFP28 are with duplex LC interface (shown as the figure below). Therefore, the cabling solutions are different respectively.

100G QSFP28 transceiver

Cabling Solution for 100G QSFP28 with MTP/MPO Interface

This kind of 100G QSFP28 transceiver is usually used with 100g MPO cable. For example, 100GBASE-SR4 QSFP28 can support 100G optical links over eight fibers and it can be connected with a 12-fiber MTP/MPO patch cable (four fibers for transmit, four fiber for receiver, leaving four fiber unused). Similar to 100GBASE-SR4 QSFP28, 100GBASE-PSM4 QSFP28 is also used with 12-fiber MTP/MPO patch cable. However, 100GBASE-SR4 QSFP28 utilizes multimode cable for 100 meters data transmission distance while 100GBASE-PSM4 QSFP28 utilizes single-mode cable for 500 meters optical links. Take 100GBASE-SR4 QSFP28 for example, the following figure shows that two 100GBASE-SR4 QSFP28 transceivers are connected with a multimode 12-fiber MTP trunk cable.

Cabling Solutions for 100GBASE-SR4 QSFP28 Transceiver

The following figure shows that with the use of multimode MTP-LC 8f fanout patch cord, one 100GBASE-SR4 QSFP28 transceiver can be connected with four 25GBASE-SR SFP28 transceivers.

100GBASE-SR4 with four 25GBASE-SR SFP28

Cabling Solution for 100G QSFP28 with Duplex LC Interface

Structured with duplex LC interface, 100GBASE-CWDM4 QSFP28 and 100GBASE-LR4 QSFP28 are usually used with single-mode patch cables with LC duplex connectors. When upgrading the network, we often meet the problem that we have to replace all the fiber patch cables. However, you do not have to worry about this issue if your transceivers are 100GBASE-CWDM4 QSFP28 and 100GBASE-LR4 QSFP28. Common single-mode duplex LC patch cable can meet the cabling requirement of these two transceivers. The following figure shows that two 100GBASE-CWDM4 QSFP28 transceivers are connected with a single-mode duplex LC patch cable.

Cabling Solutions for 100GBASE-CWDM4 QSFP28 Transceiver

Conclusion

For 100G QSFP28 with MTP/MPO interface, you can choose MTP/MPO cable, but remember that 100GBASE-SR4 QSFP28 utilizes multimode cable while 100GBASE-PSM4 QSFP28 utilizes single-mode cable; for 100G QSFP28 with duplex LC interface, you can use duplex LC patch cable for long distance transmission. I hope after reading this article, you can get something helpful. The transceivers and fiber optic cables mentioned above can be found at FS.COM. For more details, you can visit our site.

Can 40GBASE-LR4 Be Used for 4x10G?

We know that 40GBASE-SR4 QSFP+ transceiver can be used for 4x10G SFP+ connections, because it offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G over 100 meters of OM3 MMF or 150 meters of OM4 MMF. However, for 40GBASE-LR4 QSFP+ transceiver, it is commonly utilized over long transmission distance of SMF in 40G network applications. Can 40GBASE-LR4 be used for 4x10G? The answer depends and this article will focus on this question.

40GBASE-LR4 CWDM QSFP+ Transceiver Cannot Be Used for 4x10G

The 40GBASE-LR4 CWDM QSFP+ transceiver, such as QSFP-40GE-LR4, is compliant to 40GBASE-LR4 of the IEEE P802.3ba standard. It contains a duplex LC connector for the optical interface. The maximum transmission distance of the transceiver is 10km over SMF. In the transmit side, the transceiver converts 4 inputs channels of 10G electrical data to 4 CWDM optical signals by a driven 4-wavelength distributed feedback (DFB) laser array, and then multiplexes them into a single channel for 40G optical transmission, propagating out of the transmitter module from the SMF. Reversely, the receiver side accepts the 40G CWDM optical signals input, and demultiplexes it into 4 individual 10G channels with different wavelengths. Each wavelength channel is collected by a discrete photo diode and output as electric data after being amplified by a transimpedance amplifier (TIA). Therefore, 40GBASE-LR4 CWDM QSFP+ transceiver cannot be used for 4x10G. It cannot be split into 4x10G, because it uses 4 wavelengths on a pair of single-mode fiber with LC duplex connector, and does not allow itself to split into 4 pairs without substantial complexity to split out the wavelengths.

Working Principle of 40GBASE-LR4 CWDM QSFP+ Transceiver

40GBASE-LR4 PSM QSFP+ Transceiver Can Be Used for 4x10G

The 40GBASE-LR4 PSM QSFP+ transceiver is a parallel single-mode optical transceiver with an MTP/MPO fiber ribbon connector. It also offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G on 10km of single-mode fiber. The transmitter side accepts electrical input signals compatible with common mode logic (CML) levels. All input data signals are differential and internally terminated. The receiver side converts parallel optical input signals via a photo detector array into parallel electrical output signals. That’s to say, the parallel optical signals are transmitted parallelly through 8 single mode fibers. As a result, 40GBASE-LR4 PSM QSFP+ transceiver can be used for 4x10G, because it uses parallel (ribbon) fiber with MTP/MPO connector, which allows the creation of 4 fiber pairs.

Working Principle of 40GBASE-LR4 PSM QSFP+ Transceiver

Note: 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, it allows for splitting into 4x10G (single-mode).

Conclusion

In a world, the answer of question “Can 40GBASE-LR4 be used for 4x10G?” depends. The 40GBASE-LR4 CWDM QSFP+ transceiver cannot be split into 4x10G, while for 40GBASE-LR4 PSM QSFP+ transceiver, it cab be used for 4x10G. To put it simply, 40G QSFP+ transceiver which is with MTP/MPO interface can be used for 4x10G connections, otherwise, it can only support 40G link. The 40G QSFP+ transceivers mentioned above can be found in FS.COM, if you want to know more details, please visit our site.