CLB: Coarse-Grained Precision Traffic-Aware Weighted Cost Multipath Load Balancing on PISA

Abstract

This paper presents CLB, a programmable switch-based general-purpose in-network load balancer that can adapt to traffic changes at a very high speed. It uses Weighted-Cost Multipath (WCMP) mechanism for traffic-aware load balancing over many paths at a coarse-grained precision. CLB can be configured to match the load balancing requirements of a wide range of applications at line rate. We have analytically shown that CLB can achieve a bounded response time to traffic changes in the data plane. We implement CLB using the P4 programming language. Our experimental evaluation shows CLB can successfully distribute the incoming load over multiple paths for a given path-weight distribution and leads to performance improvement compared to other load balancing schemes.