Are Today's SDN Controllers Ready for Primetime?

TL;DR

This paper critically evaluates the performance of current SDN controllers, revealing inherent design limitations due to object-oriented approaches that hinder their ability to process small packets efficiently, even on advanced hardware.

Contribution

The paper provides the most extensive evaluation of SDN controllers to date and identifies fundamental design flaws related to object-oriented processing that impair performance.

Findings

Most efficient controller spends 20% of time on packet serialization

Object-oriented design causes significant per-packet overhead

Performance worsens when ported to advanced hardware like Tilera

Abstract

SDN efficiency is driven by the ability of controllers to process small packets based on a global view of the network. The goal of such controllers is thus to treat new flows coming from hundreds of switches in a timely fashion. In this paper, we show this ideal remains impossible through the most extensive evaluation of SDN controllers. We evaluated five state-of-the-art SDN controllers and discovered that the most efficient one spends a fifth of his time in packet serialization. More dramatically, we show that this limitation is inherent to the object oriented design principle of these controllers. They all treat each single packet as an individual object, a limitation that induces an unaffordable per-packet overhead. To eliminate the responsibility of the hardware from our results, we ported these controllers on a network-efficient architecture, Tilera, and showed even worse performance. We thus argue for an in-depth rethinking of the design of the SDN controller into a lower level software that leverages both operating system optimizations and modern hardware features.