Ether: Providing both Interactive Service and Fairness in Multi-Tenant Datacenters

Multi-tenant datacenters and cloud networks must provide both isolation and interactive service to tenant applications, many of which are sensitive to tail flow completion times. Network operators must also ensure high utilization of network capacity to reduce cost. Existing approaches that statically partition network capacity, in either time or space, provide good isolation but suffer from under-utilization. Existing schemes that dynamically allocate capacity to tenants incur either decreased fairness or high tail flow completion times. To overcome these limitations, we propose Ether. Ether is able to overcome these limitations because it can prioritize bursty flows during short congestion episodes while still ensuring fairness at long timescales. In this paper, we present a preliminary design of Ether and discuss its feasibility in today's programmable switches. Our evaluations show that, at high loads, Ether achieves 23% improvement in tail flow completion times (FCT) when compared with idealized fair queueing (FQ) while still providing similar fairness as FQ. In contrast, pFabric, which optimizes FCT, worsens fairness by a factor of 1.8 when compared with Ether.