Patent ID: 8908499

Claim:
A network switch comprising: a plurality of stack units linked to each other in a sequence; wherein each stack unit includes (i) a port, (ii) a forwarding engine, (iii) a first interface, and (iv) a second interface; wherein the second interface of each stack unit in the sequence is linked to the first interface of a subsequent stack unit in the sequence; wherein the second interface of a last stack unit in the sequence is linked to the first interface of a first stack unit in the sequence; wherein in response to (i) a packet traveling in a first direction from the first stack unit to the last stack unit in the sequence and (ii) a link between a second stack unit and a third stack unit in the sequence being inoperative, the forwarding engine of the second stack unit is configured to return the packet in a second direction to a preceding stack unit in the sequence; wherein the packet travels in the second direction from the preceding stack unit to the first stack unit in the sequence, from the first stack unit to the last stack unit in the sequence, and then from the last stack unit toward the third stack unit in the sequence; and wherein in response to the link between the second stack unit and the third stack unit in the sequence becoming operative subsequent to being inoperative, and in response to the packet having entered the network switch via the port of the second stack unit, (i) the forwarding engine of the third stack unit is configured to forward the packet in the second direction to the second stack unit via the link, and (ii) the forwarding engine of the second stack unit is configured to drop the packet.