In a line termination unit integrated circuit in a point-to-multipoint network, a receiver receives an upstream transmission from a network termination unit within the point-to-multipoint network, a transmitter transmits a downstream transmission to a network termination unit within the point-to-multipoint network, and an internal processor operatively coupled to the receiver processes sub-fields within the overhead field of the upstream transmission. The internal processor is also operatively coupled to the transmitter to assemble the overhead field of the downstream transmission. The upstream transmission is an upstream transmission convergence frame format having an overhead field and a payload field, and the downstream transmission is a downstream transmission convergence frame format having an overhead field and a payload field.