Control architecture using a multi-layer embedded signal status protocol

This invention relates generally to digital transmission networks and, more particularly, to embedded control of signals transported through distributed elements in digital transmission networks. Distributed switch fabrics can support multiple switching functions while meeting established performance requirements by using a control architecture based on multiple layers of signal status carried within signals transported through the distributed switch fabrics. More specifically, a method and apparatus is provided for controlling the selection of signals through distributed switch fabrics by deriving signal status information for the signals at any point along a transmission path and embedding the signal status information in each of the signals using multiple signal status layers. Each of the signals carries its respective signal status information as it propagates along the transmission path, so that the embedded signal status information can be selectively extracted from any of the multiple signal status layers to facilitate a selection decision at any of the distributed switch fabrics. The multiple layers of signal status can be used to provide a cumulative signal status of a particular signal as it propagates along the transmission path or the multiple layers can be used to support various combinations of status control, such as each layer being used to track a different level or type of status for the signal.