Evaluating the Power of Flexible Packet Processing for Network Resource Allocation

Recent hardware switch architectures make it feasible to perform flexible packet processing inside the network. This allows operators to configure switches to parse and process custom packet headers using flexible match+action tables in order to exercise control over how packets are processed and routed. However, flexible switches have limited state, support limited types of operations, and limit per-packet computation in order to be able to operate at line rate.

Our work addresses these limitations by providing a set of general building blocks that mask these limitations using approximation techniques and thereby enabling the implementation of realistic network protocols. In particular, we use these building blocks to tackle the network resource allocation problem within datacenters and realize approximate variants of congestion control and load balancing protocols, such as XCP, RCP, and CONGA, that require explicit support from the network. Our evaluations show that these approximations are accurate and that they do not exceed the hardware resource limits associated with these flexible switches. We demonstrate their feasibility by implementing RCP with the production Cavium CNX880xx switch. This implementation provides significantly faster and lower-variance flow completion times compared with TCP.