Patent ID: 7319664

Claim:
A method of managing a redundant link for use in a stack of switches comprising the steps of: connecting every two switches in the switch stack via links including the redundant link to form a closed-loop link topology; detecting a link status; deactivating the redundant link if the link status indicates that the switch stack forms the closed-loop link topology; polling each of the switches through the links within the switch stack; activating the redundant link in the switch stack if one of the switches in the switch stack fails to respond to the polling; re-initializing the switches to form a new switch stack in which the redundant link is activated; reassigning unit IDs to respective switches in the new switch stack; determining whether the new switch stack has changed from the original closed-loop link topology to another link topology; and identifying a link connected between the first switch with the lowest unit ID and the second switch with the highest unit ID as a disconnected link if the closed-loop link topology is changed; and wherein a first switch in the new switch stack is assigned to a lowest unit ID if the first switch has a downlink port with no active control signal; wherein a second switch in the new switch stack is assigned to a highest unit ID if the second switch has an uplink port with no active control signal.