Working and protection capacity, and spare capacity redundancy
Working capacity is used to establish working paths between node pairs. Total working capacity is the sum of working capacity on all the links within a network. The total working capacity or capacity cost is defined as
sum protection capacity
Protection capacity is used to establish protection paths between node pairs. Total protection capacity is the sum of protection capacity on all the links within a network. The total protection capacity or capacity cost is defined as
sum working capacity
where Cj is the unit capacity cost on span j, wj and sj are working and protection capacity units respectively on link j.
Spare capacity redundancy is defined as a ratio of total protection capacity to total working capacity, and spare capacity cost redundancy is defined as a ratio of total protection capacity cost to total working capacity cost. Spare capacity redundancy is an important criterion often used to evaluate the efficiency of a protection scheme.
