Fairness & Efficiency in Network Performance Isolation

Performance isolation and high utilization are two key requirements when sharing resources, such as network bandwidth, between tenants in a public or private cloud. Recent network sharing proposals enforce a particular policy, such as per (source-VM, destination-VM) bandwidth allocations, by explicitly enforcing rate limits between pairs of communicating VMs. We show that no single bandwidth allocation policy can capture different tenant goals, and any one policy can hurt tenant performance. Hence, we argue that the cloud provider should provide complete freedom to tenants to decide flow-level rate allocations, and enforce isolation through endpoint (VM) rate limits instead. However, enforcing isolation through static endpoint rate limits can waste bandwidth. To capture these diverse goals of tenants and the provider, we develop a game theoretic model of their interaction. We present a procedure by which a provider can compute an allocation that achieves both isolation and high utilization without explicit information about the tenants’ goals, simply by observing tenants’ usage of their allocated bandwidth.