Patent ID: 7593320

Claim:
A stackable multi-layer switch comprising: a first set of stack units comprising a master stack unit, wherein one of the stack units in the first set comprises a first port to communicate with a network using a first Internet Protocol address; and a second set of the stack units comprising a backup master stack unit, wherein one of the stack units in the second set comprises a second port to communicate with the network using the first Internet Protocol address; wherein each of the stack units comprises a control plane processor, one or more ports, a stacking interface, and a forwarding engine to communicate with the control plane processor, the ports, and the stacking interface; wherein the stack units communicate with each other through the stacking interfaces; and wherein, when the master stack unit is unable to communicate with the backup master stack unit through the stacking interfaces, the first and second ports attempt to communicate with each other over the network using a second Internet Protocol address associated with the first port and a third Internet Protocol address associated with the second port.