On partial protection in groomed optical WDM mesh networks

In this paper, we consider the problem of survivable net-work design in traffic groomed optical WDM mesh networks with sub-wavelength capacity connections. In typical sur-vivable network designs, individual sessions are provided either full protection or no protection. We consider a quality of protection (QoP) framework where a connection is pro-vided 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 net-work with static traffic and formulate the problem of pro-viding partial protection in groomed networks as an Inte-ger Linear Program (ILP); and (ii) a network with dynamic traffic that is analyzed using discrete-event simulation mod-els. The results quantify the gain in blocking probability for different partial protection scenarios.