Abstract: A type of switching fabric for exchanging variable-size frames of digital information between frame processors coupled directly or indirectly to one or more digital communication lines. It comprises one or more multi-line serial communication controllers (MSCCs), and a backplane providing a full mesh of serial point-to-point bi-directional links between each MSCC, and, in a loopback, from each MSCC back to itself. The MSCCs collectively manage the transfer of variable-size frames between the frame processors. To transfer digital information from a source line to a destination line, a frame processor coupled to the ingress line drives the switching fabric by signaling its MSCC that there is information. The ingress MSCC then switches the digital information through the backplane to the MSCC serving the frame processor coupled to the egress line. The switching fabric uses a clocking scheme that makes possible high throughput rates.

Abstract: A frame alignment method and system for communicating frames of information between at least two devices. A `start of alignment sequence` is used to cause a device that is in the misaligned state to inform the other device of this state condition in such a way that the other device itself is caused to transition to the misaligned state. The `start of alignment sequence` is therefore a frame alignment error when a device is in the aligned state. Each device in the misaligned state repetitively transmits the `start of alignment sequence`. Each device in the misaligned state transitions to the realignment state upon detection of the `start of alignment sequence`. When in the realignment state the device transmits the `end of alignment sequence` to cause the other device to transition to the aligned state if the other device is in the realignment state.