The XFP is a protocol-independent optical transceiver, typically operating at 850nm, 1310nm or 1550nm, for 10 Gigabit per second SONET/SDH, Fibre Channel, 10 Gigabit Ethernet and other applications.
XFP optics are used in datacom and telecom optical links and their benefits are a smaller footprint than other 10Gbps transponders (such as XENPAK, X2 and XPAK). The electrical interface to the host board is a standardized serial 10Gbps interface called XFI. XFP optics are a small form-factor pluggable module. It was defined by an industry group in 2002. A lot of network manufactures such as Juniper, Brocade, Alcatel-Lucent, Extreme, and Huawei are utilizing XFP optics in their routers and switches. Cisco is not using the XFP optics in many of their linecards, as they prefer the older X2 and the newer SFP+ transceivers. However, XFP optics are utilized in some Cisco SPA cards, which are used in the ASR 1002 or ASR 9000 series for example.
XFP optics come standard with a dual LC fiber connector.XFP optics are a popular industry format because of the small shape, and come in 4 different versions: SX, LX, EX and ZX. The SX version will work on Multi Mode fiber, the LX, EX and ZX work only on Single Mode fiber. The LX will reach a maximum range of 10km, the EX of 40km and the ZX of 80km. XFP optics always have a Tx (sending laser) and a Rx side (receiver). The difference between the sending power (in dB) and the receiving power (in dB) is called the power budget and will determine the distance an optic can cover, where the laser light (in nanometers) also has an important role.
Some producers of XFP optics claim to offer the 120km version but this is an enhanced version of the 80km version with a receiver that is less sensitive for wavelength dispersion. The power budget from these 120km XFP optics is not enough to reach the 120km and you would need additional amplification to achieve this range. Solid Optics can offer you the whole CWDM and DWDM spectrum for XFP optics. XFP optics are also available as Bidi optics, which has only 1 LC plus and will work on 1 single strand of fiber.