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.