400G Ethernet for data center is a hot topic these days. Though 100G network is widely deployed today, 400G is considered to be the next major Ethernet speed for data centers. In fact, cloud providers and others who require ultra-high bandwidth connectivity are developing and testing technologies for 400G Ethernet networks now. Then what exactly is 400G Ethernet network? What kind of transceiver module shall be used for 400G Ethernet link connectivity?
400 Gigabit Ethernet standard is developed by the IEEE P802.3bs Task Force. It is the logical progression from 100G Ethernet. However, 400GbE is not only four times as fast as 100GbE, but also offers a better economy of scale and a denser configuration. Unlike 100G transceivers, the 400G transceiver often has 8 channels and adopts PAM4 encoding scheme to reach 50Gbps per channel. Till now, many transceiver interface standards have been released, including 400GBASE-SR16, 400GBASE-DR4, 400GBASE-FR8, and 400GBASE-LR8.
The optical transceiver is one of the first things to consider when moving to 400G Ethernet network. Now there are various form factors for 400G optical transceivers, including QSFP-DD, OSFP, COBO, and CFP8.
QSFP-DD means Double Density QSFP. 400G QSFP-DD transceiver is a new module similar to current QSFP, but with an eight-lane electrical interface. Each lane can achieve up to 50Gbps data rate. In addition, QSFP-DD transceiver shares the same cage with the QSFP module but has a longer electrical connector. This is because QSFP-DD has an additional row of contacts (as shown above). With this design, 400G QSFP-DD is capable of backward compatible to QSFP+, QSFP28 and even QSFP56. When use a QSFP+, QSFP28 or QSFP56 transceiver in the QSFP-DD port, only one row of contacts are detected, engaging only 4 lanes of I/O (as shown below). 400G QSFP-DD transceivers are now the most popular optical modules in the market, which have been launched and manufactured by Finisar, Innolight, Vitex-Tech, Mitscomponent, etc.
OSFP stands for Octal Small Form Factor Pluggable, which is a new kind of pluggable form factor. Like 400G QSFP-DD module, OSFP transceiver also has 8 lanes supporting 50Gbps each. But it is slightly wider and deeper than the QSFP in size. Therefore, 400G OSFP port can not be back compatible to existing QSFP+, QSFP28 and QSFP56 transceivers. However, companies such as Innolight, Vitex-Tech and Eoptolink have already sold 400G OSFP transceivers on their website.
CFP8 is a new, first-generation optical transceiver form factor for 400G Ethernet applications. It has a relatively large physical size, offering the lowest port density. 400G CFP8 transceiver supports IEEE standards including 400GBASE-SR16, 400GBASE-FR8, 400GBASE-LR8, featuring a maximum transmission length of 10km. Now Finisar has launched 400G CFP8 FR8 and CFP8 LR8 optical transceivers. Oclaro also announced sampling of its 400G CFP8 transceiver for core routers/transport applications.
The COBO is named for Consortium for On-Board Optics. Unlike the above mentioned transceiver modules, 400G COBO transceivers are installed internally to the line-card equipment in a controlled environment. Though lacking of flexibility, COBO transceivers can provide higher module port density, improved thermal management, and better power efficiency. This kind of transceiver is most suitable for the new cloud market. Now 400G COBO transceiver is only a concept, which means it has not been launched by any company yet. But Microsoft is one of the main supporters for this kind of transceiver.
400G Ethernet is an inevitable trend in data centers. And as transceiver modules are fundamental for both inter and intra data center communications, the 400G transceiver will be flooding the data center transceiver market in the near future. But with various 400G transceivers, which is the best choice for next-generation data centers? In our opinion, 400G transceivers with smaller size, faster speed and lower cost will be mainstream. In this case, 400G QSFP-DD and OSFP transceiver will be much more favored. And since 400G CFP8 transceivers has good thermal management function, they will also have a small market. 400G COBO transceivers, as mentioned above, will be mainly used for the new cloud market.
FS.COM is a professional data center and enterprise network solutions provider. We always keep up with industry trends and offer the most cost-effective solutions for our clients. Now we are planning to launch the above mentioned 400G QSFP-DD, OSFP, and CFP8 transceivers. High performance 400G Ethernet switches will also be on our agenda. For more information, please visit our website at www.fs.com.Related Article: Global Optical Transceiver Market: Striding to 200G and 400G
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