The current Medium Access Control interface specifications of the Multimedia Cable Network System (MCNS) project describe a best effort access service over cable networks. In this paper, we show that even though these specifications are mainly intended to support IP traffic, there is a significant benefit in the stratification of the cable service offerings. We present a priority system to extend the MCNS MAC protocol so that differentiated services can be supported on Hybrid Fiber Coaxial networks with different levels of performance.