UNIVERSAL DIGITAL FRAMER ARCHITECTURE FOR TRANSPORT OF CLIENT SIGNALS OF ANY CLIENT PAYLOAD AND FORMAT TYPE

摘要

Client signals to be transported in a transmission network, particularly an optical transmission network, may have different payload envelope rates and are digitally mapped on the client egress side into first transport frames (also referred to as iDTF frames, or intra-node or internal digital transport frames), at the client side for intra-transport within terminal network elements (NEs) and further digitally mapped into second transport frames (also referred to as DTFs or digital transport frames) for inter-transport across the network or a link which, through byte stuffing carried out in the first transport frames so that they always have the same frame size. As a result, the system of framers provides for a DTF format to always have a uniformly universal frame rate throughout the network supporting any client signal frequency, whether a standard client payload or a proprietary client payload, as long as its rate is below payload envelope rate of the client signal. At the client signal ingress side, the signal are digitally demapped from the second transport frames (DTF format) into the first transport frames where the stuff bytes are removed and accordingly processed at an intermediate node element before further transport, or digitally demapped from the first transport frames (iDTF format) to reproduce or reassemble the client signal or signals comprising the client payload at the client payload envelope rate for reception at the client's equipment. Among various features disclosed, two predominate features are (1) a single channel or network rate for transport of all signals between network elements (NEs) and end terminal network elements and (2) the digitally wrapping of different types of payloads into N client side or first frames using stuff bytes to render each client side frame size equal to a predetermined value. Then the stuffed first frames are wrapped into line side or second frames for transport over the network at the same high speed line rate for all digitally wrapped client signals. The client side framers may be, for example, running at the lowest signal rate encountered, to digitally wrap then into parallel N client signals or digitally wrap a client signal multi-sected into N parts, where these two different client signals have different payload rates.