Patent ID: 8879444

Claim:
A method for operating a network unit to be used in a cascade stack of network units, said network unit comprising a switching engine, an external port, and a plurality of cascade ports, said method comprising: receiving a packet through the external port, wherein the packet is to be forwarded onto a cascade port of the plurality of cascade ports; providing, by a processor, the received packet with a cascade header that, uniquely across the cascade stack of network units, identifies the external port and the network unit through which the packet was received; receiving control data indicating an operational failure between at least two other network units in the cascade stack; entering, by the processor, the switching engine into a bypass mode in response to receipt of the control data to cause packets received at a cascade port of the plurality of cascade ports and intended for further transmission on the cascade stack based upon information contained in the cascade header to be forwarded without being re-directed by the switching engine; and providing, by the processor, for each packet that the network unit forwards from a cascade port of the plurality of cascade ports, a header portion that identifies which network units in the stack have and have not been traversed by the packet.