Distributed Integrated Modular Avionics (DIMA) system architecture is the main trend of the development in aerospace domain. The integrated computing system of DIMA system is distributed in physical form, but it is unified in the form of logical level. The DIMA architecture effectively modifies the problem of fault isolation, reconfiguration and resource utilization in IMA architecture. This paper presents the unified network, which is Time-triggered Ethernet network, in DIMA system. TTE network can be the integration approach for subsystem in DIMA system, because it has the advantages in low network delay and transmission determinism. And in order to verify the TTE network performance, network calculus is applied to analyze the network performance. A simulation model of TTE network is proposed and maximum network delay and backlog can be calculated by the network calculus.