CCN

Content-Centric Networking (CCN) is an information-centric networking approach that emphasizes retrieving data by name rather than by host location. In CCN, applications request data by name through Interest packets; routers route Interests toward potential sources, and Data packets containing the content are returned along the path that satisfied the Interest. The architecture aims to enable efficient content distribution, mobility support, and robustness by leveraging in-network caching.

Core components of CCN include the Content Store (CS), which is in-network cache; the Pending Interest Table (PIT), which tracks outstanding Interests and where Data should be sent; and the Forwarding Information Base (FIB), which guides router forwarding based on content names. Data packets are signed by producers, allowing receivers to verify content integrity and authenticity regardless of where the data was retrieved. Names are typically hierarchical and human-readable, enabling scalable routing and flexible namespaces.

Operation in CCN centers on two packet types: Interest and Data. When a consumer requests content, an Interest is forwarded toward potential sources. If a router has the content in its CS, it can return the Data immediately; otherwise, it forwards the Interest and records it in the PIT. When Data arrives, it is cached in the CS and forwarded to all interfaces that expressed Interests, enabling multicast-style delivery and reducing redundant transmissions.

History and status: CCN emerged from information-centric networking research in the 2000s and has seen implementations and prototypes such as the CCNx project and related work that evolved into the Named Data Networking (NDN) effort. While influential in academic settings, CCN/NDN are not widely deployed as a replacement for current IP routing, though components and concepts continue to inform contemporary content distribution research.