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 functions. 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 here: 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 [1] for both schemes, and the results are presented.