This paper introduces NEST (Network-Enforced Session Types), a runtime verification framework that moves application-level protocol monitoring into the network fabric. Unlike prior work that instruments or wraps application code, we synthesize packet-level monitors that enforce protocols directly in the data plane. We develop algorithms to generate network-level monitors from session types and extend them to handle packet loss and reordering. We implement NEST in P4 and evaluate it on applications including microservice and network-function models, showing that network-level monitors can enforce realistic non-trivial protocols.
@article{arxiv.2604.21795,
title = {NEST: Network Enforced Session Types (Technical Report)},
author = {Jens Kanstrup Larsen and Alceste Scalas and Guy Amir and Jules Jacobs and Jana Wagemaker and Nate Foster},
journal= {arXiv preprint arXiv:2604.21795},
year = {2026}
}