4 Differences Between SFP28 and SFP+

SFP28 and SFP+ are identical in form factor, then what the differences between them. This article will tell.

What is SFP+?

SFP+ is referred to as an enhanced small form-factor pluggable, which is designed for 10-gigabit data communication applications. SFP+ optical module evolved from the GBIC (Gigabit Interface Converter) module and the SFP+ specification was first published in 2006. It is much smaller in size and has lower power consumption than the GBIC module.

SFP+ modules are generally used in pairs within network devices such as switches, routers, servers, etc. A fiber optic cable or copper cable is used to connect the two-end SFP+ transceivers as the transmission media. Correspondingly, there are two types of network devices, that is fiber optic SFP+ port and Rj45 SFP+ port. The following figure shows the fiber optic SFP+ port and RJ45 SFP+ port of a Cisco network switch. The SFP+ port is plugged in SFP+ fiber optic transceivers ( SFP+ SR, SFP+ LR, etc) and connects optical fibers. And the RJ45 port is plugged in 10GBASE-T SFP+ transceivers and connects Cat6A copper cables.

What is SFP28？

Mentioned 25G SFP28 can not be separated from 100G QSFP28. 25 Gbit/s SFP28 interface is involved from the 100 Gbit/s QSFP28 interface. 100G QSFP28 interface is typically implemented with 4 lanes of 25Gbit/s channels. 25G SFP28 adopts 100Gbps Ethernet technology, implementing one 28 Gbit/s lane and accommodating 25 Gbit/s of data. SFP28 is designed for 25Gbps Ethernet. It shares the same form-factor size as SFP+. The SFP28 specification IEEE802.3by was launched in 2006. Compare to the upgrade route of 10G-40G-100G, using 25G SFP28 module as transition products can save more. So upgrading from 10G SFP+ connector to 25G SFP28 connector is more accepted by Enterprise network users. 25G SFP28 modules are also widely applied in 5G fronthaul networks, especially 25G BiDi optical transceivers.

4 Differences Between SFP28 and SFP+

SFP28 vs SFP+, what are the differences between them? The following article will tell.

Different Speeds

Although SFP28 and SFP+ optical modules look the same in appearance, the supported transmission speeds are different, which is one of the most important differences between SFP28 and SFP+. The maximum data rate of the SFP+  module is 16 Gbit/s, whereas the SFP28 module supports data rates up to 28 Gbit/s. That’s why it was called SFP28.

Since the SFP28 port is the same as the SFP+ port, here comes a question. 

Can SFP28 Run at 10Gb? 

QSFPTEK tech engineer gives the answer. When plugging SFP28 in the SFP+ port, the line speed will be determined by the switch port. Namely, it will run at 10G instead of 25G. So, the SFP28 interface is backward compatible with the SFP+ interface. What about plugging into the SFP28 port? Can the SFP28 module run at 10Gb? To run 10Gb on the SFP28 port, you need a specific dual-rate SFP28 module. The dual-rate 10/25G SFP28 module can be configured for 10G or 25G according to the switch capability. 

Different Structure and Working Principle

To increase the speed from 10Gbit/s to 25Gbit/s, the SFP28 transceiver needs to add CDR (clock data recovery) at the transmitter and CDR circuit at the receiver. The rest structure is basically the same as that of the 10G SFP+ optical module. The working principle of the SFP28 module is shown below.

Different Performance Requirements

To reach a data rate of 25Gbps in a small form factor SFP28, the SFP28 transceiver raised higher requirements for lower power consumption and heat dissipation. Moreover, the SFP28 solution has superior impedance control and less crosstalk than the SFP+.

Different Applications

Compared to the SFP+ application, the SFP28 application is more worthwhile and future-proof. SFP28 is believed to be a more effective and practical solution for the upgrading of current Ethernet and servers to 100G Ethernet. 25G SFP28 modules are more attractive to large cloud businesses and enterprise network users. SFP+ and SFP28 are both cost-effective solutions with accessible upgrade paths for high bandwidth optical transmission. However, SFP28 simplifies infrastructures while being a more future-proof solution with higher bandwidth.

Conclusion

SFP+ and SFP28 are identical in mechanical dimensions, but they are quite different in speeds, structure, working principle, performance requirements, and applications. QSFPTEK can provide a wide variety of SFP+ and SFP28 optical module types at affordable prices, welcome to consult via sales@qsfptek.com.