RAPIT: RTT-Aware Pending Interest Table for Content Centric Networking

The current Internet is facing a lot of challenges, including the transmission inefficiency due to the popularity of content-delivery applications. Content-Centric Networking (CCN) solves this problem by name-oriented routing and in-network caching. As a core component of the CCN router, the Pending Interest Table (PIT) is crucial for the forwarding performance. In this paper, we propose the RTT-Aware PIT (RAPIT) to improve the PIT efficiency in CCN by reducing the residence time of non-responded PIT entries. First, we provide an approach to measure the Round-Trip Time (RTT) from a CCN router to the content publisher and set PIT entry residence time dynamically based on the measured RTT. Second, we prioritize the PIT entries based on their aggregated request amounts and the possibility of being responded. When the PIT is exhausted, the lowest-priority entry will be replaced by the latest one. The evaluation results show that: 1) compared with current PIT with scheme in CCNx, RAPIT reduces the PIT size to 57.6% and improve the network throughput by 200%; 2) when replacement is triggered as the PIT is full, RAPIT is more accurate and improves the PIT efficiency by 20-50% compared with FIFO.