Non-Blocking In-Network Caching for High-Capacity Content Routers

Unlike IP router's stateless forwarding model, a content router owns a sophisticated data plane, consisting of a three-stage pipeline, namely, FIB, PIT, CS. Generally, a pipeline runs only as fast as its slowest stage. Compared with PIT and FIB, CS design is more challenging because it has more data to read/write, may have more entries in its table to store and lookup, and needs to organize content objects to sustain frequent cache replacement. To address CS's performance issue, we propose a novel mechanism called 'NB-Cache' from a network-wide point of view rather than a single router's. In NB-Cache, when packets arrive at a router whose CS is fully loaded, instead of being blocked and waiting for the CS, these packets are forwarded to the next-hop router, whose CS may not be fully loaded. This approach essentially utilizes Content Stores of all the routers along the forwarding path in parallel rather than checking each CS sequentially. Preliminary evaluation shows significant data plane performance improvement as 130% increase in throughput.