Consider the following simple method to collect a global snapshot (it may not always collect a consistent global snapshot): Initiator process takes its snapshot and broadcasts a request to take snapshot. When some other process receives this request, it takes a snapshot. Channels are not FIFO.
Prove that such a collected distributed snapshot will be consistent iff the following holds (assume there are n processes in the system and V ti denotes the vector timestamp of the snapshot taken process pi):
Don't worry about channel states.