Leader election in a ring As in a LAN with a ring topology, we have a number of stations—entities (at least 3). They need to elect, among themselves, a single leaden This proceeds by executing a leader election” protocol, which involves exchanging some messages. Note that the ring is unidirectional. The aim is to analyze this protocol by hand”, by drawing a part of its reachability state space, and to pointing to Interesting places” within this drawing. One of such places is that, in which a leader has been successfully chosen (exactly one entity is in the I am the leader state, while all the remaining entities are in their I am not a leader states). Please take into account the Important note from project 5.1. • Decide on how to model the entities. The FSM framework is strongly suggested. • Hint: The entities need to be “quasi-identical”, which also means that their behaviour is the same (and thus the specification of the behaviour of each of them is identical). They need, however, to differ somehow. In the original version, they differ in their address. This address is sent in the messages of a protocol. When the FSM framework is chosen, this is not possible, and the order of addresses needs to be coded into the names of signals. For you to think out the rest (the FSMs for stations may not be entirely identical, after all). • First, analyze the regular case, in which each entity (station) has a different address. This is normally the condition for the correct operation of ring networks. • Then analyze the corrupted case, in which two entities have the same address. How does the state space change? Any new faults?
Sample Solution
