Underwater Wireless Ad Hoc Networks: A Survey ◾ 399
a per-destination basis. However, TORA does not continuously execute a shortest-path com-
putation and thus the metric used to establish the routing structure does not represent a dis-
tance. e destination-oriented nature of the routing structure in TORA supports a mix of
reactive and proactive routing on a per-destination basis. During reactive operation, sources
initiate the establishment of routes to a given destination on-demand. is mode of operation
may be advantageous in dynamic networks with relatively sparse traffic patterns, since it may
not be necessary (nor desirable) to maintain routes between every (source, destination) pair at
all times. At the same time, selec ...