A Tunable Add-On Diagnostic Protocol for Time-Triggered Systems

Sustaining Property Verification of Synchronous Dependable Protocols Over Implementation

“…In a hybrid fault model, pessimistic fault modes are considered together with less severe fault manifestations. As reported in many applications (e.g., [13]), the classification of hybrid fault classes contributes to a better fault coverage and a finer diagnostic resolution. DD assumes a hybrid fault model, where no assumption is made about malicious (or Byzantine) nodes (i.e., they can send arbitrary messages), and benign nodes are always detected by every correct node based on the erroneous/missing messages sent by the faulty node (e.g., crash faults).…”

“…Consequently, implementations of a synchronous round-based protocols on TTA systems do not (in general) guarantee the desired properties, as shown in the following section. In [13] we present message alignment to remedy the overlap of different phases in case of a round-based diagnostic and membership protocol. We now show that the same mechanism can be used in TTA for the correct implementation of any round-based algorithm.…”

“…Symmetric faults are a consequence of the bus topology, however, asymmetric faults (e.g., [1], [13]) and even Byzantine behavior [4] are also possible in TTA implementations.…”

“…A mechanism called read alignment is used to delineate diagnosis of different rounds [13]. The main idea is that every node buffers the messages sent by other nodes, and computation is done based on messages that can be consistently read by all jobs.…”

“…Therefore, send alignment can be used to delay the sending of fresh data if needed [13]. In fact, if all nodes can send fresh data or, equivalently, none of them can send fresh data (like in Assumption 1), such a mechanism is not needed, since all data refer to the same TDMA round.…”