Upgrading Optical Networks with Elastic Transponders

We show how rate-adaptive transponders help reduce the cost of optical networks compared to single and mixed-line-rate solutions through a better ability to accommodate growth of traffic and uncertainties in traffic matrices during network upgrades. Introduction The bandwidth demand in core networks has been consistently growing at 20-60% CAGR and similar growth rates are expected for the 1 foreseeable future . It is therefore crucial to take such growth into account during network planning and subsequent upgrades. Two main strategies can be considered: all-period and 2 incremental planning . All-period planning assumes complete knowledge of the traffic matrix evolution over the whole life of the network and decides at T0 when and where resources should be provisioned. This strategy favours the early deployment of high-datarate channels and may require significant overprovisioning to compensate for uncertainties in the traffic matrix. On the other hand, incremental planning reassesses at several points along the life of the network which resources should be deployed. This allows one to improve estimations for the traffic matrix at each period and to better benefit from price erosion of tranport equipment. However, planning choices made in the early stages of the network life may turn out to be 2 highly constraining at latter times . This is particularly true for mixed linerate (MLR) networks which rely on datarate variety, e.g. 10, 40 and 100Gb/s to address the heterogeneity of demands in terms of both capacity and distances to be bridged.