tpIP: A Time-Predictable TCP/IP Stack for Cyber-Physical Systems

Cyber-physical systems are networks of computers connected to the physical world. Often the interaction with the physical world is time critical. In that case computation and communication must be performed in real time. However, a standard implementation of a network stack is hardly time predictable. This paper addresses the challenge of real-time communication for time-critical cyber-physical systems with a time-predictable network stack. We present tpIP, a real-time implementation of the TCP/IP stack. We achieve time predictability by two properties: (1) the application interface is based on polling functions, instead of blocking sockets, that fits for periodic real-time tasks; (2) the implementation is carefully crafted to enable static worst-case execution time analysis of all functions.