A Flat and Scalable Data Center Network Topology Based on De Bruijn Graphs

TL;DR

This paper introduces a flat, scalable data center network topology based on De Bruijn graphs that avoids hierarchical switches, ensures short paths, and uses minimal forwarding table entries for efficient routing.

Contribution

It proposes a novel flat topology using De Bruijn graphs that eliminates switch hierarchy and reduces hardware complexity while maintaining scalability and short path lengths.

Findings

Logarithmic (short) path lengths achieved.

Routing implemented with standard prefix matching in hardware.

Requires only a small number of forwarding table entries.

Abstract

Due to the requirement of hosting tens of thousands of hosts in today's data centers, data center networks strive for scalability and high throughput on the one hand. On the other hand, the cost for networking hardware should be minimized. Consequently, the number and complexity (e.g. TCAM size) of switches has to be minimized. These requirements led to network topologies like Clos and Leaf-Spine networks only requiring a shallow hierarchy of switches---two levels for Leaf-Spine networks. The drawback of these topologies is that switches at higher levels like Spine switches need a high port density and, thus, are expensive and limit the scalability of the network. In this paper, we propose a data center network topology based on De Bruijn graphs completely avoiding a switch hierarchy and implementing a flat network topology of top-of-rack switches instead. This topology guarantees logarithmic (short) path length. We show that the required routing logic can be implemented by standard prefix matching operations in hardware (TCAM) allowing for using commodity switches without any modification. Moreover, forwarding requires only a very small number of forwarding table entries, saving costly and energy-intensive TCAM.