This article presents a model development of the round trip time in a TCP/IP data network using Nonlinear System Identification techniques, normally employed in Process Control modeling. To achieve this goal, was necessary studying the tools and techniques used by Process Control Engineering and the data collection in TCP/IP data networks. This work demonstrates the effective use of these techniques in the telecommunications field for modeling complex systems like the Internet, part of it or less complex data networks like those found in the enterprise environment.