One Faulty Node Can Silence a Real-Time Bus. A Bus Guardian Stops It.
Avoiding the babbling-idiot failure in a time-triggered communication system
In a distributed hard real-time system, a single faulty node can monopolize the broadcast bus by transmitting at arbitrary times, corrupting all traffic — the babbling-idiot failure. This paper adds a bus guardian to each node that exploits the regular transmission pattern of a time-triggered system to enforce fail-silent behavior in the time domain. It details the guardian's requirements, mechanisms, and the node architecture needed to implement the technique.
In a time-triggered system, in which messages are broadcast according to a pre-determined transmission pattern, this kind of failure is characterized by the faulty node transmitting messages at arbitrary points in time, thus corrupting the transmissions on the bus.
- amingilani
Like a time-out timer (TOT) on radios?
> When activated, the Time-out Timer starts counting the moment a user begins transmitting. If the transmission continues beyond a pre-set duration, the timer automatically cuts off the transmission. This mechanism compels users to be concise in their communication and relinquish the channel, allowing others the opportunity to transmit.
— https://talkpod.com/blogs/two-way-radio-wiki/what-is-time-ou...
Edit: No, it's more like a scheduled lockout. You can only talk when it's your turn. And the assumption is that the clocks on each node are synced:
> Every node has a notion of the global time and uses
this notion along with the static schedule to establish
when it should send messages.
- ronfriedhaber
Tangent, First stumbled upon this reading Enigma's work [1].
- captainbland
We could all do with a bus guardian at times