Patent ID: 7602712

Claim:
A method of operating a switch with cut-through routing in a communications network comprising: receiving a packet at a first port of the switch, wherein the first port comprises an input buffer for receiving the packet; determining a second port of the switch from which the received packet is to be forwarded out over the network, wherein the second port supports a higher data rate than the first port, and wherein the second port comprises an output buffer to buffer a respective packet which is to be transmitted at the higher data rate, thereby preventing transmission exhaustion; performing one or more authentication checks on the received packet by checking a partition key for the packet against a partition key table implemented in content addressable memory (CAM), thereby ensuring a deterministic delay for the authentication check; applying a deterministic delay to cut-through routing of the packet by buffering the packet in the input buffer, or the output buffer, or both, wherein the delay is the larger of the time required to perform the authentication and the time required to buffer the packet sufficiently to avoid transmission exhaustion on the second port; and commencing forwarding the received packet from the second port after the delay and prior to complete reception of the packet at the first port.