Design and Dimensioning of Survivable SDH/Sonet Networks

Basically, a telecommunications network may be represented as a graph where the edges correspond to transmission cables carrying information (signals) between nodes that represent users. Associated to each pair of users there is an integer valued traffic demand which must flow through this network. Building a network in which all customers are directly connected to one another is clearly not a realistic solution due to the huge amount of cables needed to convey all the demands. Consequently, individual signals are grouped into larger aggregate signals, also called frames, and high capacity transmission equipments may then be used to transport demands more efficiently. In technical language, this grouping operation is called multiplexing and the opposite operation which consists in extracting initial information from a high capacity frame is called demultiplexing.