  The diameter of a graph is among its most basic parameters. Since a few
years, it moreover became a key issue to compute it for massive graphs in the
context of complex network analysis. However, known algorithms, including the
ones producing approximate values, have too high a time and/or space complexity
to be used in such cases. We propose here a new approach relying on very simple
and fast algorithms that compute (upper and lower) bounds for the diameter. We
show empirically that, on various real-world cases representative of complex
networks studied in the literature, the obtained bounds are very tight (and
even equal in some cases). This leads to rigorous and very accurate estimations
of the actual diameter in cases which were previously untractable in practice.
