hw2-sp11 - sender. Consider the Byzantine generals problem...

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Each question is worth 10 points. 1. In the illustration below, three processes perform multicast. Which of the following ordering property is achieved in this example? (i) FIFO ordering, (ii) total ordering, (iii) causal ordering. 2. Suppose that the timeline below corresponds to a system that implements the causal ordering algorithm for multicast discussed in class (Figure 12.16 in the textbook, 4 th edition). Mark vector timestamp at each event in the figure, and indicate for each received message at each process whether it can be delivered immediately on receipt, or must be buffered until a later time. 3. A broadcast channel is one where a message sent by a processor is received by all the processors in the system. In a reliable broadcast channel, all the processors receive the same value sent by the
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Unformatted text preview: sender. Consider the Byzantine generals problem in a system where all the processors are on the same broadcast channel. (a) In the above system, is it possible to tolerate more than n/3 faulty processors? (b) Suggest an efficient algorithm for the Byzantine general's problem in this system. 4. Exercise 12.5 from the textbook (4 th edition). 5. Consider the algorithm for the Byzantine general's problem with 4 nodes (Section 12.5.3 of the textbook, 4 th edition). Illustrate how the algorithm may not achieve correct outcome if only two of the nodes are fault-free. You may show the scenario using a figure (such as figure 12.20 in the textbook). P 1 P 2 P 3 P1 P2 P3 ECE428/CS425/CSE424: Distributed Systems Spring 2011 Homework 2 Due: by 2 pm on 02/22/2011...
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