Charon: Load-Aware Load-Balancing in P4

TL;DR

Charon is a stateless, load-aware load balancer implemented in P4-NetFPGA that passively collects server load information and uses a power-of-2-choices scheme to improve load distribution and resource utilization at line-rate.

Contribution

It introduces a novel stateless load-aware load balancer in P4 that passively infers server load and makes data-driven decisions without additional memory overhead.

Findings

Improves load distribution fairness

Enhances throughput and quality of service

Reduces processing latency

Abstract

Load-Balancers play an important role in data centers as they distribute network flows across application servers and guarantee per-connection consistency. It is hard however to make fair load balancing decisions so that all resources are efficiently occupied yet not overloaded. Tracking connection states allows to infer server load states and make informed decisions, but at the cost of additional memory space consumption. This makes it hard to implement on programmable hardware, which has constrained memory but offers line-rate performance. This paper presents Charon, a stateless load-aware load balancer that has line-rate performance implemented in P4-NetFPGA. Charon passively collects load states from application servers and employs the power-of-2-choices scheme to make data-driven load balancing decisions and improve resource utilization. Perconnection consistency is preserved statelessly by encoding server ID in a covert channel. The prototype design and implementation details are described in this paper. Simulation results show performance gains in terms of load distribution fairness, quality of service, throughput and processing latency.