Exercise 1.
Reachability Analysis
Given the
following network of two CFSMs.
Questions:
Exercise 2. Understand the protocol behavior of Alternating Bit Protocol.
Given the
alternating bit protocol,
Describe
the event sequence, starting from initial states, of the alternating bit
protocol, if channel C2 loses the even messages, i.e., it loses the 2nd, 4th,
6th,... messages. Each event can be identified as
starting global state--machine:transition->ending
global state. For example, (1,1,E,E)--S:NewData-->(2,1,E,E)
is the first event. Include events up to the one that
successfully delivers A1 to the Sender.
Ans: The event sequence is as follows:
(1, 1, E, E)—S :NewDataà(2, 1, E, E)
(2, 1, E, E)—S :-D0à(3, 1, D0, E)
(3, 1, D0, E)—R :+D0à(3, 2, E, E)
(3, 2, E, E)—R :Deliver Dataà(3, 3, E, E)
(3, 3, E, E)—R: -A0à(3, 4, E, A0)
(3, 4, E, A0)—S :+A0à(4, 4, E, E)
(4, 4, E, E)—S :New Dataà(5, 4, E, E)
(5, 4, E, E)—S :-D1à(6, 4, D1, E)
(6, 4, D1, E)—R :+D1à(6, 5, E, E)
(6, 5, E, E)—R :Deliver Dataà(6, 6, E, E)
(6, 6, E, E)—R :-A1à(6, 1, E, A1)
(6, 1, E, A1)—C2 :Lose 2nd msg A1à(6, 1, E, E)
(6, 1, E, E)—S :Toà(8, 1, E, E)
(8, 1, E, E)—S :-D1à(6, 1, D1, E)
(6, 1, D1, E)—R :+D1à(6, 8, E, E)
(6, 8, E, E)—R :-A1à(6, 1, E, A1)
(6, 1, E, A1)—S :+A1à(1, 1, E, E)