This paper will briefly address the reliability performance requirements of the Broadband Data Networking transmission system cable modem termination systems (CMTS), and HFC plant). In the context of this larger perspective, it will specifically illustrate the critical importance of a maintaining a high availability CMTS. For example, failure of a single CMTS downstream port will affect hundreds of subscribers. The service objective is to keep downtimes below 53 minutes a year (99.99% available.) This paper will then focus on techniques that can be applied to maximize the availability of the Cable Modem Termination System. Mechanisms that increase availability are redundancy, high mean time to failure and low mean time to restore. A fully distributed, no single point of failure architecture also enhances reliability. This paper will be of interest to all cable operators interested in understanding the impact of deploying high availability advanced services and how that translates into infrastructure equipment requirements.