How Much Do You Know About The QSFP56 Package?
What is the QSFP56 package?
First, let’s take a look at the appearance design of the QSFP package. The Quad Small Form-Factor Pluggable refers to the four-channel small form-factor pluggable SFP interface (QSFP). Channel SFP optical module. Compared with SFP optical modules, QSFP optical modules have higher bandwidth.
40G QSFP+ and 100G QSFP28 optical modules developed on the basis of QSFP packaging began to be gradually applied to high-density data centers. With the continuous growth of data center traffic and higher bandwidth requirements, QSFP package types have also emerged with more form factors, such as 200G QSFP56 and 400G QSFP56-DD these two package types.
The QSFP56 optical module is an upgraded version of the 40G QSFP+ and 100G QSFP28 optical modules. It is an optical module specially designed for 200G Ethernet interconnection. QSFP56 indicates that a transmission rate of 4x 50Gb/s to 56Gb/s can be transmitted in a QSFP package size. Sometimes, for convenience, QSFP56 optical module can also be called 200G QSFP optical module. According to the different transmission distances, QSFP56 optical modules can be divided into QSFP56 CR, SR, DR, FR, LR these types, which can achieve different transmission distances on single-mode and multi-mode fibers.
In general, insert two QSFP56 optical modules into the corresponding switch ports and connect them with a single-mode or multi-mode optical fiber to achieve a transmission rate of 200G. In addition, plug the QSFP56 DAC/AOC high-speed cable into the corresponding port to achieve 200G transmission. If you want to achieve a transmission rate of 2x100G or 4x50G, you can use 200G QSFP56 to 2x100G QSFP28 branch cables and 200G QSFP56 to 4x50G SFP56 branch cables.
200G QSFP56 and 200G QSFP-DD are two mainstream solutions for 200G optical interconnection. QSFP56 uses mainstream digital signal processors (DSP) to help cloud data centers deal with severe challenges and achieve faster expansion with flexible scale and cost. Optical interconnection. This article will mainly introduce you to the 200G QSFP56 packaging technology and the difference from other QSFP+ packaging.
QSFP56 vs QSFP28 vs QSFP+
From the name point of view, the package types of QSFP56, QSFP28 and QSFP+ optical modules are the same, but their transmission rate, modulation technology, interface, etc. are different. The following table lists the basic parameters of these package types:
Package Type | Year | Item Name | Number of E- Channels | Number of Optical Port Channels | Single Channel Rate | Modulation Technology | Transmission Rate |
QSFP+ | 2013 | 10G four-channel small form-factor hot-swappable optical module | 4 | 4 | 10Gbps | NRZ | 40G |
QSFP28 | 2016 | 28G four-channel small form-factor hot-swappable optical module | 4 | 4 | 25Gbps | NRZ | 100G |
QSFP56 | 2017 | 50G Four-channel small form-factor hot-swappable optical module | 4 | 4 | 50Gbps | PAM4 | 200G |
As can be seen from the above table, the QSFP56 package type optical module can support 4x50G transmission to reach a transmission rate of 200G. QSFP+ optical module is an upgraded version of QSFP optical module, which can support 4x10G transmission to realize the transmission of 10G Ethernet, 10G Fibre Channel and QDR InfiniBand. It can multiplex four channels to increase bandwidth and achieve a transmission rate of 40Gbps (10GBaud NRZ per channel). The QSFP28 optical module, like the QSFP+ optical module, includes 4 optical transmitters and 4 optical receivers, supports 4x25G transmission, and achieves a transmission rate of 100G.
The biggest difference between QSFP56 package and QSFP+, QSFP28 package is that QSFP56 no longer adopts the previous NRZ modulation technology, but adopts PAM4 modulation technology. The transmission rate of each channel can reach 50G, and it can also transmit more on the existing optical fiber. More data is more suitable for applications in ultra-large-scale data center networks.
The transformation of QSFP56 to QSFP56-DD (400G QSFP-DD) package
With the rapid development of data centers, the demand for data transmission is constantly increasing, which promotes the development of networks to higher bandwidth and higher density. At present, a new generation of 400G optical module packaging type has appeared on the market-400G QSFP-DD, where "DD" refers to double density, which means that the number of channels of 400G QSFP-DD has changed from 4 to 8 , Can reach the transmission rate of 400G.
The size of QSFP56-DD is very similar to QSFP56, but it can be backward compatible with QSFP packaged optical modules, such as QSFP+, QSFP28, QSFP56, etc. In other words, as long as the switch supports it, QSFP56 can work on QSFP56-DD ports. When the QSFP56 optical module is used on the QSFP56-DD, the port of the switch will be configured with a transmission rate of 200G instead of 400G.
Although the QSFP56-DD package is currently the most popular package type for 400G Ethernet, this does not mean that the QSFP56 package type is eliminated. For some data centers and enterprise networks that deploy 200G Ethernet, the 200G QSFP56 package type optical Modules are still the ideal solution.
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