The Cost of Traffic Protection in Bidirectional Optical Packet Switching Rings

In this paper we present a method for optimal planning of bidirectional optical packet-switched rings, with synchronized work of ring stations and an out-of-band control channel. The network stations are equipped with tunable transmitters and fixed single-wavelength receivers that can be shared by different destinations and without a limit on their number per destination. Optimal planning method that is proposed here is based on linear programming, and provides an optimal network design with minimum transportation cost per network link and receiver, for the preferred method of traffic protection. We considered 1+1 protection ("premium"), which consist in doubling the capacity of each operational connection in the ring and 1:N protection ("regular"), in which the protection capacity is shared between multiple connections, as it is not supposed to be used until an unwanted event, i.e., a failure in the network. Enabling protection in such packet ring is a novel problem and here is solved for the first time, to the best authors' knowledge. By detailed simulations we studied the impact of different protection models on the cost of the network and its configuration, and the mutual interaction between protection methods and their effectiveness. The results suggest that the cost of premium protection is up to 40 % higher than the price of regular protection, and even up to 60 % higher than the cost of the network without any protection.