FT-LAN, a fault tolerant local area network architecture for mobile mission critical systems

This effort presents a fault-tolerant LAN architecture for Mobile Mission Critical Systems (MMCS’s). MMCS’s are real-time computing platforms that perform continuously in harsh environments. It is desirable that they continue to perform a subset of critical tasks under fault conditions. The network in a MMCS can be characterized as an isolated, real-time, device-control network. A key consideration for MMCS’s is the ability of the network to support critical operations during fault conditions. The architecture we propose combines a priority-driven, real-time, LAN protocol with the adaptive earliest deadline first (AEDF) scheduling approach. Under nominal conditions the real-time protocol efficiently guarantees all message time constraints with respect to bandwidth utilization efficiency. If a fault(s) occurs, AEDF attempts to sustain critical tasks by ordering message transmissions based on value and system-state, ignoring bandwidth utilization efficiency. A significant capability of AEDF is its ability to detect and respond to the occurrence of a fault before critical message transmissions are late. A case study and simulation are presented to evaluate performance during overloads.