Scalable Pending Interest Table design: From principles to practice

Abstract

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.

Hardware accelerator to speed up packet processing in NDN router

“…Some previous studies use up to 32-bit hash values, e.g. [5,12] . When the size of the data set is in the order of million, collision is not avoidable if 32-bit hash values are used.…”

“…All-prefix match is much more time consuming than exact match. Yuan and Crowley [4,5] argue that network traffic aggregation is usually performed at edge router where the router may have large number of lower speed interfaces. On the other hand, core router has fewer interfaces but each interface has much higher line speed.…”

“…However, a pure software implementation is unlikely to be able to meet the throughput requirement of a centralized PIT for medium to large scale routers. Some software implementations based on conventional d -left and linear-chained hash tables [5,12] can only achieve packet processing rate of a few MPPS.…”

“…This will limit the overall packet processing rate. Yuan and Crowley present a software implementation of the PIT using d -left hash table [5] . The PIT is composed of d hash tables ( d is equal to 2-4).…”

“…One of the major research issues is related to the implementation of the lookup tables to support NDN packet processing [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] . Most of the previous publications on the implementation of lookup tables in NDN router are softwarebased, and up to now there are only a couple of publications on hardware implementation.…”