QSFP28 Modules for Deploying 100G Ethernet Network

It is well known that the 10G Ethernet network has been a traditional favorite that is very commonly used today, and then the 40G Ethernet network was published to keep pace with the increasing requirements. However, nowadays, the 10G/40G Ethernet network can not meet the demands of some data centers any more, and those data centers are hungry for higher network speed and larger capacity. In order to solve this, they decide to deploy the 100G Ethernet network that can accelerate the network speed and expand the network capacity greatly. Are you also eager to upgrade your system? In this paper, it will introduce the basic knowledge of QSFP28 module and some commonly used QSFP28 modules, which may guide you to deploy a smooth and fast 100G Ethernet network.

QSFP28 module is the smallest 100G form factor transceiver but has the same size as QSFP+ module used for 40G applications. Although the appearance of QSFP28 module is similar to that of QSFP+, it is a kind of optimized module with 4*25G lane that enables 100G transmission, featuring higher density and lower power consumption. When working and interconnecting for 100G data transmission, each lane can generally transmit 25G signal, and finally achieve the 100Gbps data rate. Whatrsquo;s more, the data rate each lane can be up to 28Gbps at most.

With the popularity of 100G network, the 100G modules become more and more diversifying. As the most commonly used 100G module, QSFP28 module undoubtedly has many types, for instance, QSFP28 SR4, QSFP28 LR4, QSFP28 PSM4 and QSFP28 DWDM4 module. These four kinds of QSFP28 modules are the ideal solutions for 100G transmission, which can be learned from the following figure.

QSFP28 SR4 Module

QSFP28 SR4 module is published to transmit the 100G signal for a short transmission distance, which always works through multimode fiber (MMF). In details, it can transmit 100G signal through OM3 MMF at lengths up to 70 m and through OM4 MMF at lengths up to 100 m. Meanwhile, QSFP28 SR4 module features with MTP interface, which allows for 4*25G dual way transmission over 8 fibers, as shown in the following figure.

QSFP28 LR4 Module

Clearly different from the QSFP28 SR4 module, QSFP28 LR4 module is specifically designed for 100G long distance transmission, as the letter L (long) in its name implies. This kind of QSFP28 module with duplex LC interface always works on single-mode fiber (SMF), supporting the 100G dual-way transmission up to 10 km. When it is working, WDM technology will be used for the 4*25G signals long transmission, and each 25G signal will be transmitted over different wavelength. To better understand the working principle, here offers the figure that illustrates how the QSFP28 LR4 module works to transmit the whole 100G signals.

QSFP28 PSM4 Module

QSFP28 PSM4 module has an MTP interface and four parallel lanes in each direction. Like the previous two modules, each lane of QSFP28 PSM4 module can also carry a 25G optical transmission. With the MTP interface, this module enables 100G signal transmission through eight-fiber cable, with the distance limited to 500 m. For its working principle, it can be easily learned on the following figure.

QSFP28 DWDM4 Module

QSFP28 DWDM4 module also uses the WDM technology like the QSFP28 LR4 module. When it is working, the optical multiplexer and de-multiplexer are used for separating and combining the 100G signal, so that the number of the fibers can be reduced. In fact, this kind of QSFP28 module has the ability to transmit the 100G signals through SMF with a duplex LC interface, which can also be learned from the figure below. With this kind of transmission mode, the 100G signals can be transmitted at lengths up to 2 km, which is shorter than that of QSFP28 LR4 module. While on the other hand, the 100G network deploying cost can be saved a lot for the reduced SMF.

There is no doubt that the need for 100G Ethernet network is always on the rise in recent years, and more and more modules for deploying the 100G network are put forward to face the challenge. In this paper, it simply introduces four common kinds of QSFP28 modules for 100G transmission. The first one is the QSFP28 SR4 module used for 100G short distance transmission, and the second one is the QSFP28 LR4 module that can support the 100G transmission at lengths up to 10 km. As for the third one, it is the QSFP28 PSM4 module, working with eight-fiber cable to support 100G network with 500m distance at most. And the last one is the QSFP28 DWDM4 module that can transmit the 100G signal with the distance limited to 2 km, as a cost effective solution.