International Journal of Innovative Technology and Exploring Engineering (IJITEE)
SDH possess an international standard networking principle. It is synchronous by nature so name of the hierarchy is taken from multiplexing method. The evolution of this system improving the economy of operability and reliability of a digital network SDH evolution meets the requirement of the customer with respect to the different band width requirements and different services.SDH standard defines the transmission rate developed to 155.52 mbps. In multiplexing process payloads are layered in to lower order and higher order virtual container, each including a range of over head functions for management and error monitoring.