Patent attributes
Network devices can detect whether a tunnel is available (e.g., usable to convey traffic in both directions) by implementing a tunnel detection protocol that uses a combination of idle timers and multiple types of probes. In this protocol, the device at one end of the tunnel is configured as an active device, while the device at the other end of the tunnel is configured as a passive device. The tunnel detection protocol is asymmetric; the active device sends probes to the passive device, but the passive device does not send probes to the active device. By using at least two types of probes, the active device can inform the passive device about the availability of the path from the passive device to the active device. Since the passive device does not need to send probes or process probe replies, control plane processing on the passive device can be reduced.
