Our approach to the content routing problem is to view it as, literally, a routing problem. Clients (and users) desire connectivity not to a particular server or IP address but to some piece of content, specified by name (typically a URL). Replicated servers can be viewed as offering alternate routes to access that content, as depicted in Figure 2. That is, the client can select the path through server 1, server 2 or server 3 to reach the content, assuming each server is hosting the desired content. Thus, it is the same multi-path routing problem addressed in the current Internet in routing to a host.
Figure 2: Content-Layer Routing
Network-integrated content routing provides support in the core of the Internet to distribute, maintain, and make use of information about content reachability. This is performed by routers which are extended to support naming. These content routers (CRs) act as both conventional IP routers and name servers, and participate in both IP routing and name-based routing. This integration forms the basis of the content layer. Not every router need be a content router; instead, we expect firewalls, gateways, and BGP-level routers to be augmented while the vast majority of routers are oblivious to the content layer.