PR-Trie: A Hybrid Trie with Ant Colony Optimization Based Prefix Partitioning for Memory-Efficient IPv4/IPv6 Route Lookup

Abstract

Memory-efficient Internet Protocol (IP) lookup with high speed is essential to achieve link-speed packet forwarding in IP routers. The rapid growth of Internet traffic and the development of optical link technologies have made IP lookup a major performance bottleneck in core routers. In this paper, we propose a new IP route lookup architecture based on hardware called Prefix-Route Trie (PR-Trie), which supports both IPv4 and IPv6 addresses. In PR-Trie, we develop a novel structure called Overlapping Hybrid Trie (OHT) to perform fast longest-prefix-matching (LPM) based on Multibit-Trie (MT), and a hash-based level matching query used to achieve only one off-chip memory access per lookup. In addition, the proposed PR-Trie also supports fast incremental updates. Since the memory complexity in MT-based IP lookup schemes depends on the level-partitioning solution and the data structure used, we develop an optimization algorithm called Bitmap-based Prefix Partitioning Optimization (BP 2 O). The proposed BP 2 O is based on a heuristic search using Ant Colony Optimization (ACO) algorithms to optimize memory efficiency. Experimental results using real-life routing tables prove that our proposal has superior memory efficiency. Theoretical performance analyses show that PR-Trie outperforms the classical Trie-based IP lookup algorithms.

Cuckoo Bloom Hybrid Filter: Algorithm and Hardware Architecture for High Performance Satellite Internet Protocol Route Lookup

“…In Reference [31], we introduced a new IP lookup algorithm called Prefix-Route Trie (PR-Trie). This scheme considers a special coding concept for a hybrid of prefixes and routes, which we call Overlapping Hybrid Trie (OHT).…”

“…In the original PR-Trie paper [31], we recommend the parallel version of PR-Trie that can achieve the fastest lookup and update speeds. Unfortunately, it may be impractical to employ a lot of computing and memory resources in satellite IP route lookup.…”

“…In this section, we discuss the theoretical performance of the proposed CBHF, including the false positive probability, the average number of subtrie accesses, and the lookup time. According to the IPv4 prefix partitioning scheme recommended in Reference [31] (i.e., Level 1 contains prefixes in /1 to /8; Level 2 contains prefixes in /9 to /16; Level 3 contains prefixes in /17 to /24; Level 4 contains prefixes in /25 to /32), Level 3 and Level 4, containing the most potential subtries (2 17 and 2 25 , respectively), are set to the popular levels in the CBHF, and the rest of levels are set to unpopular. Therefore, the CBHF in PR-Trie comprises two Bloom filters and two cuckoo filters.…”

“…As mentioned in Section 3.1, the counting Bloom filter is adopted in the CBHF structure, to support subtrie deletions. The basic update operation of the original PR-Trie has been provided in Reference [31], and in this paper, updates in the imaginary root table of the proposed architecture are quite easy, since there are not many imaginary roots in real-life routing tables (in quantity) and the update procedure is not necessarily performed in real-time (in terms of speed).…”

“…Table 3 reports the detailed configuration of the CBHF structure. As shown, for the Bloom filters of Level 1, there are at most two elements due to the one-bit subtrie index (i.e., IP [31]), which makes these filters safely work without the counters, and thus the width is 1 + 0 = 1 bit (array + counter). For the cuckoo filters of Level 3 and Level 4, the number of hash functions (N) is always 1 + 1 = 2 (h 1 () and f ()), and the widths are 4 × 8 = 32 bits and 4 × 16 = 64 bits (cell × fingerprint) accordingly.…”