An optical communications system, comprising a first node, first
dispersion compensation fiber located in the first node, wherein the
first dispersion compensation fiber induces dispersion onto optical
signals passing through the first dispersion compensation fiber, a second
node, a plurality of spans between the first and second nodes, and second
dispersion compensation fiber located in at least one of the spans,
wherein the second dispersion compensation fiber induces dispersion onto
optical signals passing through the second dispersion compensation fiber,
and wherein the dispersion induced by the second dispersion compensation
fiber is opposite in sign to that induced by the first dispersion
compensation fiber.