SGMII is a non-IEEE-standard mode of communication (defined by Document ENG-46158 Serial-GMII Specification from Cisco Systems) between the MAC and PHY that allows for copper 10/100/1000BASE-T (IEEE Std 802.3ab™) operation.
The SGMII specification is closely related to 1000Base-X in that each utilizes the same Physical Coding Sublayer (PCS) and Physical Medium Attachment (PMA) layers as is defined by 1000Base-X 802.3 Clause 36.
