We use an application domain specific design method, Lyra, to model a network architecture defined in the SpaceWire standard. The Lyra development method provides service-oriented approach to development of distributed communicating systems. Structurization of behavior into internal computation and externally observable behavior, and further on into different types of communication allows more efficient use of advanced formal verifi- cation and testing methods. The Lyra method has been designed particularly for industrial-strength use, so strong emphasis is on early development of the system-level integration model. The SpaceWire standard defines OSI layers 1 and 2. In this paper we focus on modeling the functionality of layer 2. We also discuss on verification of Lyra models indicating the need for more advanced verification methods and tools.