ovide reliable networking services in the face of growing traffic and diminishing revenue, we need a new approach to networking. Traditional telecom network design and implementation has followed a tried and tested approach for several decades. When new network requirements are identified, a request for proposals (RFPs) is issued by the carrier. The vendors respond with proprietary solutions that meet interoperability stan- dards, and each network operator then picks the solution they like. The networks are built by inter- connecting physical implementation of functions. Today's telecom networks have over 250 distinct network functions deployed-switches, routers, access nodes, multiplexors, gateways, servers, etc. Most of these network functions are implemented as stand-alone appliances-a physical "box" with unique hardware and software that implements the function and conforms to standard interfaces to facilitate interoperability with other boxes. For operational lease, network operators prefer to use one or two vendors, typically, for a given class of appliances (routers, for example). The appliance vendor often uses custom hardware to optimize the cost/performance; the software is mated with hardware, and the product can be thought of as "closed." This creates vendor lock in, and since most deployed appliances are seldom replaced, the result is a platform lock in, with limited options for upgrading with technology advances. Figure 1.1 qualitatively depicts the evolution of cost over a 10-year period. For purposes of illustration, the unit cost signifies the cost for performing one unit of the network func- tion, (e.g., packet processing cost for 1 GB of IP traffic). Due to platform lock in, any cost improve- ment comes from either hardware redesigns at the plug-in level with cheaper components, or price concessions made by the vendor to maintain market position. On the other hand, technology advances characterized by advances in component technology (Moore's Law) and competitive market dynam- ics, facilitate a