Patent ID: 6724781
Filing Date: 2004-04-20
Classification: H04J,H04L

Abstract:
A SONET Add/Drop Multiplexer (ADM) for processing data packets having an overhead section and a payload section, the SONET ADM having three interfaces, an east SONET interface, a west SONET interface, and a local add/drop interface, comprising:east and west SONET agents for sending and receiving SONET data signals to and from the ADM and two other SONET ADMs coupled to the east and west SONET interfaces. east and west packet-over-SONET (POS) agents coupled, respectively, to the east and west SONET agents for transporting data packets within the SONET data signals; and a protection switching agent including two fast downstream data path circuits, one fast downstream data path circuit coupling the west POS agent to the east POS agent and the other fast downstream data path circuit coupling the east POS agent to the west POS agent; wherein the protection switching agent receives and buffers only a portion of the data packets including at least a portion of the overhead section and routes this portion to the fast downstream data path circuits which examine an embedded virtual channel identifier within the portion and determines by comparing the virtual channel identifier within the overhead section to a stored look-up table of virtual channel identifiers associated with the SONET ADM, whether to forward the entire data packet to another SONET ADM via one of the east or west SONET interfaces, or to forward the entire data packet to a local node coupled to the SONET ADM via the local add/drop interface; wherein the protection switching agent further includes a packet buffer coupled to one of the SONET interfaces, and a packet multiplexer coupled to the output of the packet buffer and the local add/drop interface for multiplexing onto a second SONET interface the data packet received from the one SONET interface and the local add/drop interface.