Communications system
The present invention consists of an information structure conceived for the transport of data in digital form from a transmitting element to a receiver. This structure calls for fields for transport of the data and heading information fields termed “overhead” which improve transmission reliability. This structure enables support of digital interconnections in an element of a transport network capable of switching various traffic types such as CBRx (for example STM-N e OC-N), VC-N, STS-N or ODUk. The structure also enables identification of the frame beginning, verification of the integrity and correctness of the switching, support of protection switching, and transport of quality and timing information associated with the switched entities.
1. A method of transporting traffic information from an input interface to an output interface of a network element capable of switching different types of traffic information, the method comprising the steps of:
forming an information transport frame structure comprising a plurality of fixed size sequential frames with each frame comprising at least one overhead section, one data stuffing section, and a data section, the data stuffing section and the data section being sized for containing together at least the traffic type which requires most capacity among those expected and,
upon reception on the input interface of data of a traffic type, mapping in the frame said data filling with said data all the data section, and continuing in the data stuffing section and, if the traffic type requires less space than that arranged in the frame, filling extra space with stuffing bytes to maintain the frame size with a change in transported traffic type,
configuring the structure with fixed dimensions and being repeated at regular intervals, and
the traffic type transported being one of optical data unit-index unit k (ODUk), synchronous transport signals (STS-n), synchronous digital hierarchy (SDH) virtual containers (VC-n), or constant bit rate signals (CBRx).
2. An apparatus, comprising:
at least one input interface;
at least one output interface; and
a transmitter for transmitting data between the interfaces in a frame structure for supporting digital interconnections between a transmitting element and a receiving element for alternatively transporting therebetween different types of alternative traffic including traffic comprised in optical data unit-index unit k (ODUk) traffic and traffic not comprised in ODUk traffic,
the structure having at least one overhead section sized to allow mapping therein of overhead information, and a data section sized to allow mapping therein of characteristic data of each type of alternative traffic transported,
the structure having fixed dimensions and being repeated at regular intervals, and
wherein the traffic type transported is one of ODUk, synchronous transport signals (STS-n), synchronous digital hierarchy (SDH) virtual containers (VC-n) or constant bit rate signals (CBRx).