Many cloud applications can benefit from guaranteed latency for their network messages, however providing such predictability is hard, especially in multi-tenant datacenters. We identify three key requirements for such predictability: guaranteed network bandwidth, guaranteed packet delay and guaranteed burst allowance. We present Silo, a system that offers these guarantees in multi-tenant datacenters. Silo leverages the tight coupling between bandwidth and delay: controlling tenant bandwidth leads to deterministic bounds on network queuing delay. Silo builds upon network calculus to place tenant VMs with competing requirements such that they can coexist. A novel hypervisor-based policing mechanism achieves packet pacing at sub-microsecond granularity, ensuring tenants do not exceed their allowances. We have implemented a Silo prototype comprising a VM placement manager and a Windows filter driver. Silo does not require any changes to applications, guest OSes or network switches. We show that Silo can ensure predictable message latency for cloud applications while imposing low overhead.

Datacenter networking has brought high-performance storage systems' research to the foreground once again. Many modern storage systems are built with commodity hardware and TCP/IP networking to save costs. In this paper, we highlight a group of problems that are present in such storage systems and which are all related to the use of TCP. As an alternative, we explore Trevi: a fountain coding-based approach for distributing I/O requests that overcomes these problems while still efficiently scheduling resources across both networking and storage layers. We also discuss how receiver-driven flow and congestion control, in combination with fountain coding, can guide the design of Trevi and provide a viable alternative to TCP for datacenter storage.

Ideally, everyone should be free to use as much of the Internet resource pool as they can take. But, whenever too much load meets too little capacity, everyone's freedoms collide. We show that attempts to isolate users from each other have corrosive side-effects - discouraging mutually beneficial sharing of the resource pool and harming the Internet's evolvability. We describe an unusual form of traffic policing which only pushes back against those who use their freedom to limit the freedom of others. This offers a vision of how much better the Internet could be. But there are subtle aspects missing from the current Internet architecture that prevent this form of policing being deployed. This paper aims to shift the research agenda onto those issues, and away from earlier attempts to isolate users from each other.