Patent ID: 7317681

Claim:
A failure recovery method in a dual optical ring network including an inner ring and an outer ring, a plurality of nodes, a first concentrator and a second concentrator, wherein each node includes at least an interface A and an interface B each comprising an input interface and an output interface, said method comprising the steps of: connecting interface A of every even node and interface B of every odd node directly to said first concentrator and connecting interface B of every even node and interface A of every odd node directly to said second concentrator; configuring said first concentrator and said second concentrator so as to connect said plurality of nodes to form two counter-rotating optical rings; in the event of a failure of a concentrator, configuring interfaces in said plurality of nodes connected to the failed concentrator to loopback configuration; and configuring said surviving concentrator such that the interfaces of said plurality of nodes are connected in daisy chain fashion so as to form a single optical ring.