Deterministic Ethernet technologies are becoming the primary backbone communications network for Integrated Modular Avionics (IMA) system architectures. ARINC-664 Part 7 and AS6802 (TTEthernet) are two examples of deterministic Ethernet implementations. In order to ensure optimal performance, and predictable deterministic operations, all components of ARINC-664 and AS6802 networks must have all communications parameters statically pre-configured unlike their dynamically configured and adaptive counterparts used commonly in data communications networks. Additionally, these deterministic Ethernet technologies require unique test, integration, and simulation solutions. Standard Ethernet testing tools typically do not provide the special set of features needed to support effective and efficient verification and validation of IMA systems based on deterministic Ethernet. This paper provides an overview of the ARINC- 664 and AS6802 deterministic Ethernet technologies and discusses the unique requirements associated with testing and integrating these types of networks. Specifically, the challenges faced by system integrators, network architects, and sub-system designers are covered. A flexible test and simulation solution, which provides effective and efficient support for deterministic Ethernet network and subsystem design as well as system integration activities, is presented.