VeriTable: Fast Equivalence Verification of Multiple Large Forwarding Tables

TL;DR

VeriTable is a novel algorithm that rapidly verifies the forwarding equivalence of multiple large IP forwarding tables, significantly improving speed and efficiency over existing methods, and addressing challenges posed by longest prefix matching.

Contribution

The paper introduces VeriTable, a fast, single-traversal algorithm for verifying equivalence of multiple large forwarding tables, handling LPM lookups efficiently.

Findings

Outperforms state-of-the-art in speed and memory efficiency

Works effectively for both IPv4 and IPv6 tables

Reduces verification time significantly

Abstract

Due to network practices such as traffic engineering and multi-homing, the number of routes---also known as IP prefixes---in the global forwarding tables has been increasing significantly in the last decade and continues growing in a super linear trend. One of the most promising solutions is to use smart Forwarding Information Base (FIB) aggregation algorithms to aggregate the prefixes and convert a large table into a small one. Doing so poses a research question, however, i.e., how can we quickly verify that the original table yields the same forwarding behaviors as the aggregated one? We answer this question in this paper, including addressing the challenges caused by the longest prefix matching (LPM) lookups. In particular, we propose the VeriTable algorithm that can employ a single tree/trie traversal to quickly check if multiple forwarding tables are forwarding equivalent, as well as if they could result in routing loops or black holes. The VeriTable algorithm significantly outperforms the state-of-the-art work for both IPv4 and IPv6 tables in every aspect, including the total running time, memory access times and memory consumption.