Coordination of spare lane usage between link partners

Various examples of techniques for identifying a corrupt data lane and using a spare data lane are described herein. Some examples include a system of coordinating spare lane usage between link partners. One such example comprises analyzing data from a link partner to identify a corrupt lane, and communicating the corrupt lane to the link partner, wherein the communication does not require sideband communication channel. In some embodiments, communicating the corrupt lane to the link partner comprises identifying a transmit lane corresponding to the corrupt lane, transmitting a set of data intended for a corresponding transmit lane using a spare data lane, and transmitting bad data to the link partner using the corresponding transmit lane.