This amendment to IEEE Std 802.3-2002 as amended by IEEE Std 802.3ae-2002, IEEE Std 802.3af-2003 and IEEE Std 802.3aj-2003 specifies a new physical layer medium dependent sublayer interface for 10Gb/s Ethernet. 10GBASE-CX4 specifies an equipment interconnect based on the 10 Gigabit Attachment Unit Interface (XAUI) for up to 15m of balanced shielded cabling.

The scope of this project is to specify additions to and appropriate modifications of IEEE Std 802.3 as amended by IEEE Std 802.3ae-2002 (and any other approved amendment or corrigendum) to add a copper Physical Medium Dependent (PMD) option for 10 Gb/s operation, building upon the existing 10GBASE-X Physical Coding Sublayer (PCS) and 10 Gigabit Attachment Unit Interface (XAUI) specifications.

The purpose of this project is to provide a lower-cost option for interconnection of closely located equipment (within ~15m of cable), typically within a stack or between equipment racks within a room.