A SONET/SDH topology that employs two active optical fibers in a dual counter-rotating ring configuration. All traffic moves in both directions. Should the primary ring fail, the secondary ring is already active in the reverse direction, thereby providing protection from network failure. A path-switched approach also improves error performance because the receiving stations examine both data streams and select the better signal. See also line-switched ring, optical fiber, SDH, SONET, and topology.