A Two-Hop Segment Protecting Paradigm that Unifies Node and Span Failure Recovery under p-Cycles

This letter explains that protecting segments of exactly two hops within an optical network is alone enough to prevent both single span and node failure events. More specifically, we show how to transform a network (topology and working routes) from the two-hop segment perspective and then perform a p-cycle design for the new network. Experimental results typically suggest that two-hop protecting p-cycles are preferable to span- and path-protecting p-cycles for degree-3 or more network instances. The overall two-hop segment protection framework is applicable to any other span-survivability scheme.