25G Ethernet is defined as a cost and performance optimized solution for server and switch connection. As data centers are expanding at an unprecedented pace, it hence demands higher speed between server and switch. To catch up the trend, network infrastructures are undertaking the great migration to a new direction – 25G and 50G Ethernet, from which network professionals can reap significant benefits from enhanced density, speed and performance. This article explains some unique benefits of 25G Ethernet and addresses basics of the standard 25G SFP 28 spec.
25G Ethernet Decoding
Ethernet 25G links utilize a single-lane connection similar to existing 10GbE—but it delivers 2.5 times more data. While compared with 40GbE connectivity, 25G Ethernet connection requires only one lane (four with 40GbE) but offers superior switch port density, lower costs and power requirements. Moreover, 25G Ethernet takes existing module form factors, such as SFP28 and QSFP28, and allows for a breakout connection that is configurable as either 25G per lane or the full 100G without changing the port on the front of switches. Another major advantage of 25G Ethernet in that it also takes existing optical plants and increases the bandwidth by 2.5 without changing the physical infrastructure. 25G Ethernet effectively reduces CAPEX and OPEX while meets the necessary I/O bandwidth requirements in data centers.
25G SFP28 Spec: What Makes It Special?
The IEEE 802.3by specification was released in June 2016 to address Ethernet 25G data rates. It covers the SFP28 form factor, which looks the same as the 10G SFP+. And it also includes the QSFP28 form factor and the QSFP28 to four SFP28 breakout cables. 25G Ethernet has ushered in this new SFP28 spec, which significantly maximizes network performance and scalability, while decrease capital and operating expenses. SFP 28 spec helps pave the road for cloud and web-scale data center to deploy bandwidth-intensified applications. Here we offer a SFP28 vs. SFP+ vs. QSFP28 comparison.
SFP28 vs. SFP+: Same Form Factor With Different Speed
SFP28 spec is regarded as the enhanced version of SFP+ that designed for 25G signal transmission. SFP28 utilizes the same familiar form factor as SFP+, but the electrical interface is upgraded to handle 25Gbps per lane. Since its transmission rate can reach up to 28Gbps, the engineering and industry name is SFP28. Since SFP28 adopts the same form factor as SFP+, it will work sufficiently on SFP+ ports, and SFP+ cables can be plugged into SFP28 ports although they are not designed for 25Gb/s data rates. When it comes to copper cable, SFP28 copper cable possesses significantly greater bandwidth and lower loss compared with SFP+ version.
SFP28 vs. QSFP28: What Are the Differences?
With the number 28 in both of their name, SFP28 and QSFP 28 module actually adopt different working principle: SFP28 modules support 25Gb/s over a single lane, which allows for error-free transmission of 25Gb/s up to 100m over OM4 multimode fiber. While QSFP28 supports four independent channels with data rates ranging from 25 Gb/s up to potentially 40 Gb/s. Both of them can be used in 100G networks, but the SFP28 is applied in the form of QSFP28 to SFP28 breakout cables.
Conclusion
25G Ethernet is the trend to embrace, and it unleashing the power of SFP28 transceiver to deliver enhanced bandwidth, superior impedance control and less crosstalk. SFP28 spec enables a new generation of high-density 25G Ethernet switches, which facilitates server connectivity in data centers, and offers cost-effective upgrade path for enterprises deploying 10G Ethernet links today to 100G or even 400G in the future.
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