Regarding the ARINC 429 data standard, there is only one talker per bus, and many listeners. AIMS acts as a data conversion gateway for a good deal of the data on the 777, and is the core of the 777 avionics. There are redundant 429 busses in some cases, but often only one per device (talker). ARINC 629 is a many talker, many listener bus that is like an ethernet LAN in a way. There are 3 main ARINC 626 busses on the 777, the Flight Controls, Systems, and AIMS Intercabinet busses. The flight controls bus consists of 3 separate sub-busses (twisted pairs), while the Systems and AIMS busses each have 4 twisted pairs (for redundancy).
Critical system failure rates are typically designed for 1E-9 per flight hour.