Networks today are the product of reactive evolution to demand. Circuit-switched networks built for providing POTS (Plain Old Telephone Service) evolved into the current multi-layered networks in reaction to pressures for new services and increased capacity. Growth of data traffic in particular has consistently outstripped the most aggressive projections, forcing service providers to continuously build out their networks using this inefficient and costly network model.
Responding to these pressures, the telecommunications industry has built networks which may well be reaching the end of their viability. Multi-layered networks have become so complex that the cost of continuous development to meet demands is becoming prohibitive. This section presents three key issues that have brought traditional networks architectures to a crossroads: complexity, cost and the need to protect investments.