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ECE428 Homework 2
This assignment has 4 questions with 60 points in total. The solutions must be typed, and submitted
via Blackboard. However, the diagrams can be hand-drawn. You must acknowledge any sources
used to arrive at your solutions, other than the course materials and textbook. All homework
assignments are expected to be an individual work, so no collaborations are allowed.
Question 1: The only things guaranteed in life are FIFO channels [20 points]
Consider a system with pair-wise FIFO communication channels. Explain, which of the ordering
properties FIFO, causal, and/or total ordering will be satisfied in the following four scenarios. For
each ordering property, either explain (in one or two sentences) why it will be satisfied, or provide a
counter-example, for example, using a diagram. The same counter-example can be used for
different scenarios. For B-multicast over FIFO channels, explain whether and why it automatically
satisfies causal ordering, or provide a counterexample.
(a) B-multicast in a situation where there are no process failures;
(b) R-multicast in a situation where there are no process failures;
(c) R-multicast in a situation where process failures may occur;
(d) The sequence number-based FIFO multicast algorithm discussed in class.
Questions 2-4 are on the next pages
