XENPAK is a 10G optical fiber transceiver which supports a variety of physical interfaces, including single mode fiber, multi mode fiber and CX4 Infiniband copper cables. The XENPAK standard is defined in the Multisource Agreement (MSA), which defines a fiber optic or copper transceiver module conforming to the IEEE 802.3ae 10GbE (10 Gigabit Ethernet) standard.