In order to meet various requirements, various types of optical modules have been produced. Classification by rate In order to meet the requirements of various transmission rates, optical modules with different rates have been produced: 100GE optical module, 40GE optical module, 25GE optical module, 10GE optical module, GE optical module and FE optical module. Classification by package The higher the transmission rate, the more complex the structure. In order to meet the requirements of different structures, various packaging types of optical modules have been produced. The applicable encapsulation types of switches are: CFP encapsulation, QSFP+ encapsulation, QSFP28 encapsulation, XFP encapsulation, SFP encapsulation, eSFP encapsulation and SFP+ encapsulation. All optical modules support hot plug. SFP(Small Form-factor Pluggable) optical module: small pluggable package. The SFP optical module supports LC optical fiber connectors. ESFP (enhanced small form-factor pluggable) optical module: enhanced SFP, sometimes referred to as SFP. It refers to SFP with monitoring functions of voltage, temperature, bias current, transmitted optical power and received optical power. SFP+(small form-factor pluggable plus) optical module: refers to the SFP module with increased speed. XFP (10gb small form-factor pluggable) optical module: "x" is the abbreviation of Roman numeral 10, and all xfp modules are 10GE optical modules. XFP optical module supports LC optical fiber connector. Compared with SFP+ optical module, XFP optical module is wider and longer. SFP28 (small form-factor pluggable 28) optical module: The interface package size is the same as SFP+, and it supports the Sfp28 optical module with the speed of 25G. QSFP+(quad small form-factor pluggable) optical module: four-channel small hot-pluggable optical module. QSFP+ optical module supports MPO optical fiber connector, which is larger than SFP+ optical module. CFP(Centum Form-factor Pluggable) optical module: the dimension of length× width× height is defined as 144.75mm×82mm×13.6mm, which is a high-speed and hot-pluggable new optical module standard supporting data communication and telecommunication transmission. QSFP28 optical module: The interface package size is the same as QSFP+, and it supports QSFP28 optical module with a speed of 100GE and QSFP+ optical module with a speed of 40GE.