I think the purpose is to solve the scenario where each node has a perfect internal clock, but no external reference clock. A rough solution is to initiate a count from the origin, starting from 0. Each node hears the previous neighbor's count, increments it by 1 and sounds off. When the end node is reached, it knows how far the signal propagated. At this point a reverse count is initiated, terminating in 0 at the origin. Each node along the way back hears the adjacent node begin its countdown, and starts its own countdown from its relative position. The return signal reaches the origin node just as the remainder of the nodes reach 0, and all node execute simultaneously on 0 (with appropriate modification for any fencepost problems).

No external reference clock is required, and assuming each node counts at exactly the same rate, all nodes act in unison.