Scalable Routing Easy as PIE: a Practical Isometric Embedding Protocol (Technical Report)

TL;DR

PIE is a practical, scalable routing protocol that uses virtual coordinates for efficient, low-stretch greedy routing on large networks like the Internet, with high delivery success and adaptability.

Contribution

This paper introduces PIE, a novel isometric embedding-based routing scheme that is scalable, easy to implement, and effective on any graph, especially Internet-like networks.

Findings

Achieves 100% packet delivery with low path stretch.

Scales efficiently on Internet-like graphs with minimal memory.

Adapts quickly to network changes, improving delivery ratios.

Abstract

We present PIE, a scalable routing scheme that achieves 100% packet delivery and low path stretch. It is easy to implement in a distributed fashion and works well when costs are associated to links. Scalability is achieved by using virtual coordinates in a space of concise dimensionality, which enables greedy routing based only on local knowledge. PIE is a general routing scheme, meaning that it works on any graph. We focus however on the Internet, where routing scalability is an urgent concern. We show analytically and by using simulation that the scheme scales extremely well on Internet-like graphs. In addition, its geometric nature allows it to react efficiently to topological changes or failures by finding new paths in the network at no cost, yielding better delivery ratios than standard algorithms. The proposed routing scheme needs an amount of memory polylogarithmic in the size of the network and requires only local communication between the nodes. Although each node constructs its coordinates and routes packets locally, the path stretch remains extremely low, even lower than for centralized or less scalable state-of-the-art algorithms: PIE always finds short paths and often enough finds the shortest paths.