Simulation-Based Verification of Network Protocols Performance

Formal verification techniques need to deal with the complexity of the systems being verified. Most often, this problem is solved by taking an abstract model of the system and aiming at a complete verification of an approximation of the system. This paper proposes a complementary verification approach, in which the approximation is introduced into the verification algorithm, instead of the system model: we achieve an approximate verification of a fairly complete and detailed system model. The proposed technique relies on coupling a Genetic Algorithm with a simulator of the system under verification, and is especially suited for verifying performance-related aspects. To prove the effectiveness of our approach, we applied it to the quantitative verification of a network protocol: the TCP protocol operating on a given network. A Genetic Algorithm is able to find a configuration of the traffic over the network that sensitizes a critical problem in the TCP protocol that would be difficult to find both with exact techniques and stochastic ones.