In high-capacity optical WDM networks, the failure of a network component such as a fiber link may disconnect many optical lightpaths, leading to severe disruption in network services. Therefore it is imperatively important to provide fast and full protection against any failure in optical WDM networks. The method of pre-configured protection cycles (p-cycles) is very attractive for design of survivable optical networks. So far p-cycle approach has been extensively studied for design of survivable optical networks where traffic demand is static. In this paper, we first briefly describe our recently proposed p-cycle design heuristic and then show how to apply this heuristic to optical networks where traffic demand is dynamically changing. We consider three different strategies to configure dynamic p-cycles for dynamic traffic demands, and compare their performance in terms of blocking probability and computational time.

This paper proposes an optimal design scheme for photonic transport networks that interconnect multiple wavelength division multiplexing (WDM) self-healing ring systems by using optical cross connects (OXCs). To calculate the number of OXCs required in each hub to interconnect these ring systems, a virtual mesh network is generated, on which the route of each optical path (OP) going through multiple adjacent rings ("ring" is defined as circle in network topology) is determined based on a list of hubs. An integer-programming-based design problem is then formulated that minimizes the overall cost of facilities including OXCs as well as ring systems to accommodate a given demand. By solving this problem, we can simultaneously optimize required number of ring systems in each ring, wavelength assignment within each individual bidirectional ring system, required number of OXCs in each hub, and capacity to be allocated to each OP. Numerical examples show that the ring-based network is more cost-effective than the mesh restorable network when the cost of an OADM is lower than that of an OXC, and the OXC-to-fiber cost-coefficient ratio is sufficiently large.