uilt, debugged, and operational can be risky and should not be attempted without careful planning and deliberate, task oriented, sequential steps. Similar to the end-to-end service model, the reference architecture simply lays out the functional components and shows how they relate. The NID or premises equipment interfaces and interoperates with the network to set up and tear down connections, monitor performance, and process alarms. The desired content transport network leverages one or more routing, switching and transport capabilities, depending on requirements and configuration of the access facilities. In situations where multiple types of traffic are converged onto a common access facility, the access facility must be channelized and mapped to the particular transport. For example, voice grade dialup or switched 3 CONTENT TRANSPORT NETWORK DEFINED service would have channel capacity sufficient to accommodate peak voice demand on the public switched telephone network (PSTN) or integrated services digital (ISDN) network. However, if the design called for voice-over IP, some amount of bandwidth would be re- quired to accommodate a similar level of voice traffic. CPE is a router configured to connect to peer routers at the other loca- tions. The router must be sized and have features selected to perform the functions required by the servers. These functions vary and depend on the encoded bit rate or payload of the content and level of traffic. Another factor for careful consideration is distance between peer devices at other locations. If the distance is short, such as a nearby building, Ethernet could be an option. But outside adjacent buildings within a campus environment it's likely construction and capital cost will quickly add up to make third-party service providers with IP transport capability attractive. Access facilities provide basic connectivity between the CPE and the MAN or WAN. Likely alternatives include E3/DS3 or OC3/STM1. Choosing an appropriately sized access facility is a matter of making a c