Patent ID: 8743677

Claim:
As system, comprising: a first network including a first plurality of network devices, wherein the first network has a first spanning tree associated therewith; and a second network including a second plurality of network devices, wherein the second network has a second spanning tree associated therewith, wherein the second spanning tree is separate from the first spanning tree; wherein a core network connects the first network to the second network; wherein the first plurality of network devices includes first and second redundant network devices connected to the core network; wherein the first and second redundant network devices are connected by an inter-device link, wherein traffic from or to the core network cannot be transmitted on the inter-device link; and wherein the first and second redundant network devices are configured to: send a first packet, by the first redundant network device, to the second redundant network device over the inter-device link indicating that the first redundant network device is in an active state; by the second redundant network device, force down a first connection port connecting the second redundant network device to the core network in response to receiving the first packet, thereby blocking traffic to and from the core network via the second redundant network device; by the second redundant network device, send a second packet to the first redundant network device over the inter-device link in response to the first connection port being forced down, the second packet indicating that the second redundant network device is in an inactive state; and by the first redundant network device, set up a second connection port connecting the first redundant network device to the core network in response to receiving the second packet, thereby permitting traffic to and from the core network to be forwarded via the first redundant network device.