The title really speaks for itself. Given what we know about Alcubierre drives (and yes, I know they're extremely hypothetical, but for this question let's just assume they can exist as we currently understand them), and assuming some "magical" method of instant communication across many light years of distance, how might interstellar warfare play out between two states or coalitions, relatively equivalent in power and technology, spanning across scores or hundreds of stars? 

Assume that each state or coalition feels sufficiently threatened by the other that the complete annihilation of the other seems to be the only way to reliably secure the permanence of their own existence, and that both sides have established some kind of Dyson swarm around at least some of the stars they own. What might this war look like? Would there be mutually assured destruction or would it just drag on forever? Would combat between Alcubierre drive powered ships be plausible, or even possible? How might they go about attacking a star system? Would there be any reasonable way to defend against such an attack? Ultimately, what would be the overall nature of such a war?