Evaluating modular node architectures with limited shelf interconnection [Invited]

In order to simplify and speed up optical network dimensioning, the client-to-line ports interconnection restrictions imposed by the node architecture deployed are typically disregarded. However, as some node architectures can impose restrictions in the client-to-line ports interconnection, some grooming optimizations may be precluded. This is particularly relevant in multi-period scenarios where client traffic is churned between periods. In this case, depending on the node architecture deployed, hitless client traffic churn can be impossible to perform and manual intervention is required. In this work, we present an integer linear programming-based framework that minimizes the number of modules required considering the client-to-line interconnection restrictions. Moreover, the model also computes the client traffic churn blocking probability. The four node architectures considered are nonblocking electrical cross connect (EXC), standalone EXCs, EXCs with extendable backplanes, and EXCs with interconnection via high bit rate client ports. Using the proposed models, we evaluate the impact of node architecture flexibility on the probability of blocking traffic. The results show that EXCs with interconnection via high bit rate client ports tend to reduce the percentage of blocked traffic compared to the remaining modular architectures when the number of required shelves is higher than 2.