Getting the Future Trends from 40G/100G Network to 400G

Updated on Jul 20, 2022

FS 100G Data Center Switches

The development of high-definition video, VR, the Internet of Things, and cloud computing has accelerated the upgrade requirements of network bandwidth. The average annual growth rate of Internet traffic remains at a high level, which is also the main reason for promoting data centers to upgrade from 40G/100G to 400G. Compared with the 10G/25G network, the 40G/100G network still has certain advantages in capacity and performance. However, with the development of technology, the cost-effectiveness brought by the 400G network is gradually gaining popularity.

Trends for 40/100G Network to 400G

Around 2022, the market shares of 40G/100G networks and 400G networks are relatively flat. The technical application of 400G also highlights the advantages of the 400G network in the future network.

Market Trends

The emergence of 100G technology has become a technological turning point in the telecommunications industry, and some enterprises have upgraded to 100G. Today, the rapid growth of Internet traffic has made 100G networks no longer able to meet bandwidth requirements, and small and medium-sized enterprises are also preparing to migrate to 100G. However, 400G technology has gradually swept the market since its emergence, and enterprises that once upgraded to 100G networks are moving towards 400G.

The data graph of the number of Ethernet port devices and DWDM shows that the competition between 100G and 400G is still going on. In the future, 200G/400G networks will occupy a large part.

100G and 400G trends

From the global market in 2021, the east-west traffic of data centers accounts for about 70%. It is much higher than the traditional north-south traffic trend, which means that many enterprises have completed the upgrade of their network architectures. The north-south traffic is dominated by 1G/10G networks, which are used in small enterprises. Most of the east-west traffic of medium and large enterprises is 25G/40G/100G network. Based on the 100G network, some large cloud data centers in North America have moved towards 400G trend.

400G trend

40G/100G to 400G Technology Trends

The technical application of 400G improves the efficiency of data transmission and also supports the connection scheme of branch cables. The development of optical chips in 400G networks is also becoming more mature, making 400G more cost-effective.

PAM4: PAM is a new signal transmission technology following NRZ encoding. Compared with NRZ signals, PAM4 uses 4 channels for data transmission, transmits two-digit logic information within the clock cycle, and the code rate of the signal is twice that of NRZ. The use of PAM4 in 400G transceivers can greatly improve data transmission efficiency.

8-channel solution: Traditional parallel transmissions use 12 or 16 fibers for network connections that increase power consumption. Whlie 400G branch link solutions, such as 4x100G, 8X50G, can improve transmission efficiency while reducing wiring complexity, allowing the use of 100G network equipment to smoothly upgrade to 400G network.

Optical chip: 100G transceivers are mainly based on the 25Gbaud/s chip, using DML and VCSEL modulated laser, NRZ signal to achieve the 100G network. The 400G optical chip adopts DML laser and supports the rate of 56Gbaud to achieve higher performance.

400G coherent technology: The coherent technology of 400G on the long-distance transmission network has matured, and data transmission over 80km can be realized through WDM. At the same time, 400G also improves the transmission bandwidth and distance of the OTN network, enabling the OTN network to achieve large-bandwidth and long-distance transmission without relays, which plays an important supporting role for the OTN network in the commercial use of 5G.


Difference Between 40G/100G Network and 400G Network

The 40G network breaks through the 4x10G connection, and the transmission distance using multimode fiber can be as high as 400m. 100G network has a larger capacity, lower latency, and better transmission performance than the 40G network. In terms of transmission interoperability, 10G and 40G WDM technologies have limitations in supporting LAN services. Due to the size of ODU2 (optical density unit) and ODU3 containers, 10GELAN cannot be fully transparently transmitted. The 100G WDM technology solves the problems of transparent transmission and interoperability of various rate Ethernet services and supports a unified mapping method. Additionally, the 100G network also supports the connection of branch cables to complete the smooth upgrade of low-speed networks, such as 4x25G, 2x50G.

400G network capacity and transmission efficiency are higher than 40G/100G. Since its larger network bandwidth also supports 4 or 8 fiber transmission, the cabling is easy to manage. Simultaneously, a single 400G port costs less than a 4 x 100G port connection, which reduces power consumption.

Considerations of Upgrading from 40G/100G Network to 400G

In the process of upgrading from 40G/100G to 400G, the branch port and rate configuration need to be reconsidered. 400G transceivers usually need to use the corresponding fiber jumpers for 16x25G, 8x50G or 4x100G channel data transmission. Hence, the above case should be considered when using existing 100G switches and optical modules. Corresponding fiber jumpers can be selected, like the 8-core MTP fiber patch cables that can achieve 100% utilization of 8x50G.

Since 400G uses PAM4 modulation, and traditional 100G optical modules use 25G NRZ signals, they cannot interoperate with 400G optical modules in 4x100G. QSFP28 100G-DR and 100G-FR support 100G PAM-4 on the optical interface and 4x25G NRZ on the electrical interface, enabling single-channel data transmission. In addition, 400G QSFP-DD is backward compatible with 40G/100G transceivers, enabling the rapid upgrade of 40G/100G networks.


The increasing demand for existing Internet traffic has promoted the continuous upgrading of the network. As the mainstream trend of the previous generation, the 100G network has gradually entered a mature and stable stage. The 400G network has exerted great advantages in data center networking, metropolitan area network, and data center interconnection, and the development of technology will continue to expand the cost-effectiveness, which is why 400G networks will be the new mainstream trend after 100G.


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