ModNet: A Modular Approach to Network Stack Extension

The existing interfaces between the network stack and the operating system are less than ideal for certain important classes of network traffic, such as video and mobile communication. While TCP has become the de facto transport protocol for much of this traffic, the opacity of some of the current network abstractions prevents demanding applications from controlling TCP to the fullest extent possible. At the same time, non-TCP protocols face an uphill battle as the network management and control infrastructure around TCP grows and improves. In this paper, we introduce ModNet, a lightweight kernel mechanism that allows demanding applications better customization of the TCP stack, while preserving existing network interfaces for unmodified applications. We demonstrate ModNet's utility by implementing a range of network server enhancements for demanding environments, including adaptive bitrate video, mobile content adaptation, dynamic data and image compression, and flash crowd resource management. These enhancements operate as untrusted user-level modules, enabling easy deployment, but can still operate at scale, often providing gigabits per second of throughput with low performance overheads.