The 10G optic modules have been developed from 300Pin, XENPAK, X2, XFP and finally achieve with the small size SFP+. 10G SFP+ by virtue of its lower cost, smaller size and other advantages to meet the needs of high-density equipment, SFP+ has replaced the XFP 10G modules and became the mainstream.
10G XFP modules are hot-swappable and protocol independent. XFP operates at optical wavelengths of 850nm, 1310nm or 1550 nm. Principal applications include 10 Gbit /s Fibre Channel, Synchronous optical networking (SONET) at OC-192 rates, Synchronous optical networking STM-64, 10 Gbit /s Optical Transport Network (OTN) OTU-2, and parallel optics links. They can operate over a single wavelength or use dense wavelength-division multiplexing techniques. They include digital diagnostics that provide management that were added to the SFF-8472 standard. XFP modules use an LC fiber connector type to achieve high density.
SFP+ and XFP in Comparison
-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.
-SFP+ is compliance with the protocol of IEEE802.3ae, SFF-8431, SFF-8432.
-SFP+ has a more compact form factor package than XFP.
Both of SFP+ and XFP are 10G fiber optical modules and can connect with other type of 10G modules.
XFP ports only accept XFP optics, and XFP optics are only 10G. An XFP optic cannot be used in an SFP+ port, and vice-versa. The two are not interchangeable, but they are compatible. Meaning they can be used at opposite ends of a physical link, as long as they conform to the same wavelength and signaling rate. For example, a 10Gbps Ethernet Single Mode LR XFP on one end will work fine with a 10Gbps Ethernet Single Mode LR SFP+ on the other end.
This is not like copper, where you can have a port that is able to run at multiple speeds (10/100/1000). With fiber, the optical transcievers are built to pulse light at a fixed frequency, and they do not "scale" down to interoperate with slower speeds. A 10G optic can only transmit and receive signals at 10G on both ends.
The Advantages of SFP+ Modules
An SFP+ port can accept (usually) a variety of optics. That's going to vary by the particular switch. If the switch accepts 1G and 10G optics in the SFP+ port, then you can put in whatever optics suit your needs. 1G optics are usually labelled as SFP (or mini-GBIC), and 10G are usually SFP+. If you put a 10G optic in, it will not operate with a 1G optic on the other end of the link.