Compiling minimum incremental update for modular SDN languages

Abstract

Measurement results show that updating rules on switches poses major latency overhead during the course of the policy update. However, current SDN policy compilers do not handle policy updates well and generate large amount of redundant rule updates, most of which modify only the priority field. Our analysis shows that the lack of knowledge on the rule dependency and the consecutively distributed priority numbers are the fundamental problems behind the redundancy. In this paper, we propose to tackle the problems through 1) an extended policy compiler that builds rule dependency along with the compilation, and 2) an online optimization algorithm that maintains a scattered priority distribution. Our preliminary evaluation demonstrates that our proposed patch can eliminate nearly all the priority updates.