Solutions for 40G Short Distance Transmission

It is well known that SFP+ transceivers like SFP-10G-SR and SFP-10G-SR-S are very commonly used and perform greatly in 10G short distance transmission. When higher bandwidth is required, several SFP+ transceivers can be used together to offer multiple 10G links as a common solution. However, if an individual 40G link is implemented in this case, it has the ability to perform higher with much faster data transmission rate than multiple 10G links. As the deployment of 40G Ethernet network is not so simple as that of 10G Ethernet network, the following will introduce three widely applied solutions for short distance transmission in 40G Ethernet network which can be useful for you to deploy individual 40G link instead of multiple 10G links.

With the popularity of 40G Ethernet network, 40G solutions, especially 40G QSFP+ modules, have been widely applied to finish 40G data transmission. At present, there are various kinds of 40G solutions available on the market, which are designed to support different applications. For 40G short distance application, three widely applied solutions, QSFP-40G-SR4, QSFP-40G-CSR4 and 40GBASE-CR4 QSFP+ direct attach copper cable will be introduced in details.

QSFP-40G-SR4 module is one of the most popular fiber optic transceiver for 40G short distances transmission, designed with 40GBase-SR4 standards. It is able to support high-bandwidth 40G signal transmission through 12-fiber parallel fiber, which is always terminated with MPO/MTP multi-fiber connectors. How long can it transmit 40G signals? If it works with OM3, it can support the 40G link at lengths up to 100 meters. If it transmit the 40G signals through OM4, the distance can be longer, 150 meters. In addition, QSFP-40G-SR4 module has the ability to connect four SFP-10G-SR modules by an 8-fiber MTP to 4 duplex LC cable. The following is an example of this module working with OM4 that you can find at FS.COM.

As for QSFP-40G-CSR4 module, it is always referred to as an upgraded version of QSFP-40G-SR4 module that has a better performance to support 40G short distance transmission. Its working principle is similar to the previous one, which also works through 12-fiber parallel cables with MPO/MTP connectors to support 40G optical link. Besides, connection with four 10GBase-SR interfaces still can be done in a parallel 4x10G mode by using duplex fiber breakout cables. What higher performance does QSFP-40G-SR4 module have? In fact, it is reflected on the transmission distance which is extended to 300 meters through OM3 and 400 meters over OM4. Here offers an example of QSFP-40G-CSR4 module that works with OM3 for your reference.

40GBASE-CR4 QSFP+ DAC can be also called 40GBASE-CR4 QSFP+ cable, which is very different from the first two 40G solutions. It is a pre-terminated copper cable with both ends terminated with QSFP+ modules. As for its working principle, it uses four lanes of twinaxial cable delivering serialized data at a rate of 10.3125 Gbit/s per lane to finish the 40G signal transmission.

Compared to the above-mentioned 40G modules, 40GBASE-CR4 QSFP+ DAC has a much lower manufacturing cost which is always not considered as a real optics, because of no expensive lasers or electronic components. At the same time, the transmission distance is also much shorter limited by the property of copper cable. In fact, it can only support the 40G signal transmission with a reach of 7 meters. Here also lists an example of 40GBASE-CR4 QSFP+ DAC for you to get a better understanding of the differences between this one and the above-mentioned modules.

If the 10G Ethernet network can not meet your demands any more, you are suggested to deploy 40G Ethernet network for much higher bandwidth and faster data transmission rate. As for the 40G solutions for short distance transmission, you can choose it according to the transmission distance your network requires. In general, 40GBASE-CR4 QSFP+ DAC would be a good choice to support your system within 7 meters with the lowest price, while QSFP-40G-SR4 module is much more suitable to be used in the application within 150 meters. As for QSFP-40G-CSR4 module, it is the most expensive but optimal solution that has the ability to support 40G signal transmission at lengths up to 400 meters.