Comparisons Among SFP, SFP+, XFP, SFP28, QSFP/QSFP+, CFP and QSFP28

In the data center, various types of optic module transceiver are seen everywhere, such as SFP, SFP+, XFP, SFP28, QSFP/QSFP+, CFP and QSFP28. However, for those who get in touch with them for the first time, just like me, maybe most information, is unfamiliar to them. Fortunately, I have right collected some materials about them some time ago. Today, I want to share it here in the form of comparison to help those who need them.

To be easier to understand them, it will be better to know their basic information before getting the differences between them. The below is about their brief introduction according to the order of development history.

SFP

SFP, small form-factor pluggable for short, is a compact, hot-pluggable fiber optic transceiver used for both telecommunication and data communications applications. Optic module sfp can be regarded as the upgrade version of GBIC module. Unlike GBIC with SC fiber optic interface, SFP is with LC interface and its main body size is only about half of GBIC, helpful to save the space of SFP. Meanwhile, SFP is a popular industry format supported by many network component vendors. It’s designed to support SONET, Gigabit Ethernet, Fibre Channel, and other communications standards.

SFP+

SFP+ is an enhanced version of the SFP that supports data rates up to 10 Gbit/s and  also supports 8 Gbit/s fibre channel, 10-gigabit Ethernet and optical transport Network standard OTU2. Initial standard applications focused on 8G fibre channel, 10G Ethernet and 10G fibre channel, where the electrical interface to the host board is a standardized serial interface called SFI. Besides, in applications, it has been expanded to SONET OC-192, SDH STM-64, OTN G.709, CPRI wireless, 16G Fibre Channel, and the emerging 32G fibre channel application. Similar to SFP, SFP+ is Also a popular industry format supported by many network component vendors

XFP

XFP has appeared before the SFP+. It is also a standardized form factor for serial 10 Gb/s fiber optic transceiver. It is protocol-independent and fully compliant to the following standards: 10G Ethernet, 10G fibre channel, SONET OC-192, SDH STM-64 and OTN G.709, supporting bit rate from 9.95G through 11.3G. XFP optical transceivers are used in datacom and telecom optical links and offer a smaller footprint and lower power consumption than other 10 Gb/s transponders. In addition, the electrical interface to the host board is a standardized serial 10 Gb/s interface called XFI.

SFP28

SFP28, as the enhanced version of SFP+, is designed for 25G signal transmission. It utilizes the same familiar form factor as SFP+, but the electrical interface is upgraded to handle 25Gbps per lane. On account that its transmission rate can reach up to 28Gbps, the engineering and industry name is SFP28. SFP28 is considered the rising sun in the industry to deliver enhanced bandwidth, superior impedance control and less crosstalk. Meanwhile,SFP28 transceiver support 25Gb/s over a single lane, which allows for error-free transmission of 25Gb/s up to 100m over OM4 multimode fiber.

QSFP/QSFP+

QSFP is short for quad (4-channels) small form-factor pluggable. It is a compact, hot-pluggable optic module, used for data communication applications. QSFP+ is upgraded as the standard to support 10Gb/s data rates per SFF-8436. While QSFP products support Quarter small form-factor pluggable with the different data rate so that there is no changes in the product solution. Nowadays, QSFP+ gradually replace QSFP and is widely used due to its higher bandwidth.

CFP

CFP, namely C form-factor pluggable, is a multi-source agreement to produce a common form-factor for the transmission of high-speed digital signals. The C stands for the Latin letter C to express the number 100 (centum), because the standard was primarily developed for 100 Gigabit Ethernet systems. It can support a wide range of 40 and 100 Gb/s applications such as 40G and 100G Ethernet, OC-768/STM-256, OTU3, and OTU4.

QSFP28

100G QSFP28 transceiver module is with high density and high speed designed for 100Gbps applications. It has the same form factor as the QSFP+ optical link module. QSFP28 100G optics offer four channels of high-speed differential signals with data rates ranging from 25 Gbps up to potentially 40 Gbps, and finally meet 100 Gbps Ethernet (4×25 Gbps) and 100 Gbps 4X InfiniBand Enhanced Data Rate (EDR) requirements. QSFP28 fiber optic module recently is available in several standards—100GBASE-SR4, 100GBASE-LR4, 100GBASE-PSM4 and 100GBASE-CWDM4. QSFP28-100G-SR4 operates over multimode fiber for a distance of 100 m. While 100GBASE-LR4 QSFP28 supports a much longer distance of 10 km. Compared with CFP form factors, QSFP28 optics are more popular on the 100G optics market.

After knowing these basic knowledge about them, these differences among them are easier to get.

SFP VS SFP+: Compared with SFP, SFP+ is an update vision of SFP. SFP usually support 1.25Gbit/s to 4.25 Gbit/s while SFP+ supports data rates up to 10 Gbit/s. SFP and SFP+ have the same size and appearance, but have different in standard, because SFP is based on IEEE802.3 and SFF-8472.

SFP+ VS XFP: By comparison of earlier XFP modules, SFP+ modules leave more circuitry to be implemented on the host board instead of inside the module. The size of SFP+ is smaller than XFP, thus it moves some functions to motherboard, including signal modulation function, MAC, CDR and EDC. XFP is based on the standard of XFP MSA while SFP+ is compliance with the protocol of IEEE 802.3ae, SFF-8431, SFF-8432.

CFP VS QSFP+: QSFP+ (Quad Small Form-Factor Pluggable Plus) modules offer customers a wide variety of high-density 40 Gigabit Ethernet. The CFP is a hot-pluggable transceiver module form factor that supports a wide range of 40Gb/s and 100Gb/s applications such as 40G and 100G Ethernet.

SFP28 VS QSFP 28: SFP28 and QSFP 28 module actually adopt different working principle. As it was mentioned previously, 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. As for QSFP28, it 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.

Above all is about these information I want to share, hoping it can benefit you a lot. Meanwhile, if you want to know more or other information, maybe you can contact Infiberone.

Note: Infiberone is an online store of Gigalight.