1. A network controller to communicate with a link partner, the network controller comprising: a receiver circuit to receive a control frame from the link partner, wherein the control frame includes at least one field for specifying credit for at least one traffic class, wherein the credit is based on available space in a receive buffer associated with the at least one traffic class; and a transmit scheduler module to send data packets to the link partner based on the credit, the data packets associated with the at least one traffic class.