Patent ID: 7742401

Claim:
A network switching device, comprising: a first CPU coupled to a first memory, the first memory containing a first system software image; a second CPU coupled to a second memory, the second memory containing a copy of the first system software image; a first scheduler generating a first control signal; a second scheduler coupled to the first scheduler, the second scheduler generating a second control signal; a first switching fabric coupled to the first scheduler; a second switching fabric coupled to the second scheduler; a multiplexer receiving a first input signal from the first switching fabric and a second input from the second switching fabric, and generating a multiplexer output signal; and a port interface module receiving the output signal from the multiplexer, the port interface module receiving the first control signal from the first scheduler and the second control signal from the second scheduler, wherein an upgraded system software image is transferred to the second memory by the first CPU, the upgraded system software image is installed to the second CPU by the first CPU, and the second CPU is restarted to execute the upgraded system software image, and then the switching device stops control packet transmissions from the first scheduler, disables active fabric control signals from the first scheduler, enables active fabric control signals from the second scheduler, waits a period of time for transiting data to exit the switching device, enables control packet transmission from the second scheduler to make the second scheduler an active scheduler, and makes the second switch fabric an active switch fabric with no data loss, and wherein the upgraded system software image indicates a target hardware type and the upgraded system software image is validated before being installed to the second memory by validating that the target hardware type matches the hardware type of the switching device.