Scalable Pending Interest Table Design: From Principles to Practice

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A Pending Interest Table (PIT) is a core component in Named Data Networking. Scalable PIT design is challenging because it requires per-packet updates, and the names stored in the PIT are long, requiring more memory. As the line speed keeps increasing, e.g., 100 Gbps, traditional hash-table based methods cannot meet these requirements. In this paper, we propose a novel Pending Interest Table design that guarantees packet delivery with a compact and approximate storage representation. To achieve this, the PIT stores fixed-length fingerprints instead of name strings. To overcome the classical fingerprint collision problem, the Interest aggregation feature in the core routers is relaxed. The memory requirement and network traffic overhead are analyzed, and the performance of a software implementation of the proposed design is measured. Our results show that 37 MiB to 245 MiB are required at 100 Gbps, so that the PIT can fit into SRAM or RLDRAM chips.