The effect of interconnect schemes on the dependability of a modular multi-processor system with shared resources

AlliedSignal's Avionics & Lighting business unit is expanding the performance of its flight safety avionics by means of functional integration (added functionality enabled by exchanging information between traditionally stand-alone subsystems), as well as physical integration (sharing of system resources) and full dual redundancy. Major performance goals of this integrated modular architecture are a significant increase in system dispatchability and reduction of the loss-of-function probability of individual junctions. Success of this architectural migration depends on the scheme that is used to fully interconnect the various processing and input/output modules. Two of the considered interconnect schemes are discussed: a dual LAN and a dual-dual LAN. In both schemes, all modules can receive data from all LANs. In the prior scheme, all system modules have time-multiplexed transmit privileges on both LANs. In the latter scheme (patent pending), the modules are grouped into two identical sets. The modules in a set can only transmit on two of the four LANs. Dependability of the system has been modeled and analyzed with the HIMAP tool for both schemes, and the results are presented.