  Given a network of fixed size $n$ and an initial distribution of data, we
derive sufficient connectivity conditions on a sequence of time-varying
digraphs for (a) data collection and (b) data dissemination, within at most
$(n-1)$ iterations. The former is shown to enable distributed computation of
the network size $n$, while the latter does not. Knowledge of $n$ subsequently
enables each node to acknowledge the earliest time point at which they can
cease communication, specifically we find the number of redundant signals can
be truncated at the finite time $n$. Using a probabilistic approach, we obtain
tight upper and lower bounds for the expected time until the $\textit{last}$
node obtains the entire collection of data, in other words complete data
dissemination. Similarly tight upper and lower bounds are also found for the
expected time until the $\textit{first}$ node obtains the entire collection of
data. Interestingly, these bounds are both $\Theta (\text{log}_2(n))$ and in
fact differ by only two iterations. Numerical results are explored and verify
each result.
