X2 optical module is the main type of package module in 10G optical module, developed from XENPAK. It is a hot-swappable input/output device, mainly used for Ethernet X2 port switches or routers and network connection ports.

　　Historical development of X2 optical module:

　　X2 is evolved from the Xenpak standard, and its internal functional modules are basically the same as Xenpak and the application on the circuit board. Only one module is used to realize the function of the 10G Ethernet optical interface. Because the Xenpak optical module needs to be slotted on the circuit board with complicated operation when it is installed on the circuit board, and high-density applications cannot be realized. The improved X2 optical module (its volume is only about half the size of Xenpak) can be directly placed on the circuit board, so it is suitable for high-density rack systems and PCI network card applications.

　　Features and applications of X2 optical modules:

　　The X2 also uses the Xenpak electrical interface, with a few exceptions. X2 provides a 4-bit port address space, one less than Xenpak. X2 also reduces the number of power pins and makes the backplane and electrical ground common. X2 retains 4 vendor-specific pins of Xenpak. In terms of optical technology, the X2 supports 10GbE (Ethernet), OC192 Synchronous Optical Network, 10GFC (Fibre Channel) and other standards.