BurstBalancer: Do Less, Better Balance for Large-scale Data Center Traffic

Layer-3 load balancing is a key topic in the networking field. It is well acknowledged that flowlet is the most promising solution because of its good trade-off between load balance and packet reordering. However, we find its one significant limitation: it makes the forwarding paths of flows unpredictable. To address this limitation, this paper presents BurstBalancer, a simple yet efficient load balancing system with a sketch, named BalanceSketch. Our design philosophy is doing less changes to keep the forwarding path of most flows fixed, which guides the design of BalanceSketch and balance operations. We have fully implemented BurstBalancer in a small-scale testbed built with Tofino switches, and conducted large-scale NS-2 simulations. Our results show that BurstBalancer achieves 5%similar to 35% smaller FCT than LetFlow in symmetric topology and up to 30 x smaller FCT in asymmetric topology, while 58 x fewer flows suffer from path changing. All related codes are open-sourced at Github(2).