On partial protection in groomed optical WDM mesh networks

In this paper, we consider the problem of survivable network design in traffic groomed optical WDM mesh networks with sub-wavelength capacity connections. In typical survivable network designs, individual sessions are provided either full protection or no protection. We consider a quality of protection (QoP) framework where a connection is provided partial protection, i.e. when a link failure occurs on the primary path, the protection bandwidth provided on the backup path is less than or equal to the primary bandwidth. Each connection request specifies the primary bandwidth and a minimum backup bandwidth required. The network will guarantee at least the minimum backup bandwidth and, if capacity is available, higher backup bandwidth up to the primary path´s bandwidth. The advantage of such a model is that it can reduce backup capacity requirements based on connection needs leading to lower blocking probability and lower network costs. We consider two scenarios: (i) a network with static traffic and formulate the problem of providing partial protection in groomed networks as an integer linear program (ILP); and (ii) a network with dynamic traffic that is analyzed using discrete-event simulation models. The results quantify the gain in blocking probability for different partial protection scenarios.