XENPAK is a Multi-Source Agreement (MSA). It defines a fiber-optic or wired transceiver module which conforms to the 10 Gigabit Ethernet (10GbE) standard of the Institute of Electrical and Electronics Engineers (IEEE) 802.3 working group. The XENPAK MSA was publicly announced on March 12, 2001 and the first revision of the document was publicly released on May 7, 2001. The most recent revision of the MSA, Issue 3.0, was published on September 18, 2002. The result covered all physical media dependent (PMD) types defined by the IEEE at that time for 802.3ae 10GbE.
XENPAK Transceiver is packed in a 4.8×1.4×0.7 inch package, using DFB laser components. The working distance of XENPAK modules via G652 multimode fiber could reach up to 10km. Another important component inside the XENPAK module is the MUX/DEMUX part, which consumes 50% of the power and results in the bigger size. Its components inculde these following parts: