Reducing the size of pending interest table for content-centric networks with hybrid forwarding

Content-Centric Networking (CCN) is a novel networking paradigm that treats the named contents, not the hosts, as the first-class citizens of the network. In the forwarding plane, CCN employs a stateful forwarding scheme, which maintains per-packet state information in Pending Interest Table (PIT). By employing stateful forwarding, CCN enables native support for content requests aggregation and multicast. However, the stateful forwarding scheme requires large-sized PITs with extremely high access speed to store per-packet state information, leading to scalability issue. To overcome the issue, this paper proposes a Hybrid forwarding scheme based on content POPularity (HyPOP) for CCN. HyPOP classifies the contents into popular and unpopular contents, and uses the stateful and Bloom Filter based stateless forwarding schemes to forward the popular and unpopular contents, respectively. The mathematical analysis results demonstrate that if PITs only store state information for popular contents, the small-sized PITs are sufficient for achieving satisfactory forwarding performance. Furthermore, the extensive simulation results also verify that HyPOP can reduce the size of PIT significantly and achieve promising forwarding performance.