Spare Capacity Allocation

This chapter introduces spare capacity allocation schemes performed either off-line for a static deployment, or on-line during a time interval between two consecutive network events (i.e., a connection setup or tear-down). As survivability becomes one of the most important issues in the design of control and management of WDM networks, development of protection and restoration schemes became critical to network applicability and/or revenue-making capability. As mentioned in Chapter 6, pre-planning or pre-configuration of spare capacity for some working paths with stringent quality-of-service requirements, are the most commonly seen approaches for achieving this goal. However, if the allocation of spare capacity cannot be both capacity- and computation-efficient, the applicability of the algorithms may be limited, and the network cost for control and management increased. Therefore, we need to develop a spare capacity allocation scheme which meets the requirements of computation-efficiency, capacity-efficiency, class of service, and adaptability to traffic variation.