Cisco Content Delivery Engines (CDEs) are a family of carrier-class appliances that power the Cisco Content Delivery System (CDS), an innovative, network-based, modular platform for video delivery. The Cisco CDS delivers an unprecedented level of scalability and reliability while giving service providers a distinct service-velocity advantage in enabling the next generation of personalized entertainment and interactive media. The Cisco CDS platform combines Cisco CDEs with Content Delivery Applications (CDAs), software elements that provide ingest, storage, caching, personalization, streaming, and other real-time, scalable, and resilient capabilities. Cisco CDEs and CDAs can be flexibly configured to support a host of networked value-added services that service providers can rapidly deploy to attract and retain subscribers.Cisco Content Delivery Engines form the hardware foundation of the Cisco Content Delivery System platform, and consist of a number of networked, multifunction server appliances that can be centrally managed as a single "virtual" server. Each Cisco CDE within the virtual server performs one or more functions depending on which of the Content Delivery Applications are installed on it.Designed for maximum flexibility, Cisco Content Delivery Engines can be grouped into arrays that operate as a single logical system. Service providers can easily expand capacity by simply attaching additional CDEs to the array, thereby achieving virtually unlimited video storage and streaming capacity. The Cisco Content Delivery System employs a hierarchical storage design that allows service providers to maintain huge content libraries while actually simplifying content storage management. With a logically distributed architecture that can separate ingest and storage from streaming, each function can be scaled independently of the other by simply adding another Cisco CDE, which dynamically increases the pooled ingest, storage, caching, and streaming resources available throughout the network.Cisco CDEs adapt automatically to unpredictable and rapidly changing traffic patterns. The platform preserves video programming in a common, shared storage array that is instantly accessible for streaming anywhere in the network. Cisco's Intelligent Caching technology automates the distribution of video content between Cisco CDEs by responding dynamically to actual viewer demand and popularity trends. This adaptive content distribution model helps ensure that the content that is most popular at any point in time at each network node is always available in local storage, significantly reducing the bandwidth burden on the network backbone. This flexible architecture and the effectively unlimited scalability of content libraries make the Cisco CDS an attractive solution for efficiently and cost-effectively delivering "long-tail" content, network-based time-shifted programming, and user-generated content. This serves to increase the network's scalability while at the same time minimizing capital expenditures and operating expenses.Cisco CDEs are also designed for fault-tolerant operation. They can share state and work together as a single logical pool of resources that can be dynamically reallocated across the network's available hardware capacity in response to service requests. In the event of hardware failure, the Cisco CDS immediately delegates the functions being performed by the failed device to other Cisco CDEs in the network. Furthermore, the system automatically discovers the addition or removal of a Cisco CDE and reconfigures itself without service disruption or manual intervention, vastly simplifying maintenance and upgrade operations.A network populated with Cisco CDEs becomes a platform upon which new services and applications can be layered over time and deployed much more quickly than was possible in the past. The platform unleashes the power of IP networking technology by creating a video infrastructure capable of delivering nonstop availability, great scalability, and low total cost of ownership. Taking advantage of the extensible architecture of the Cisco CDS, operators can deploy on-demand video services today with the knowledge that they can expand their services to support real-time applications and multiple forms of rich-media content delivered to many types of devices.