  Stability of synchronization in delay-coupled networks of identical units
generally depends in a complicated way on the coupling topology. We show that
for large coupling delays synchronizability relates in a simple way to the
spectral properties of the network topology. The master stability function used
to determine stability of synchronous solutions has a universal structure in
the limit of large delay: it is rotationally symmetric around the origin and
increases monotonically with the radius in the complex plane. This allows a
universal classification of networks with respect to their synchronization
properties and solves the problem of complete synchronization in networks with
strongly delayed coupling.
