Patent ID: 7970278
Filing Date: 2011-06-28
Classification: H04J

Abstract:
1. A method of protection switching for an open multiple-ring network, comprising: detecting a failure occurring at a failure point of a first ring based on optical supervisory channel (OSC) signal; opening the first ring with a first optical switch at the point adjacent to the failure; opening a second ring with a second optical switch at a corresponding point of the second ring; closing a remainder of the first ring and of the second ring such that the first ring comprises no open points other than the failure point and such that the second ring comprises no open points other than the opened corresponding point; in a first node of the network that is immediately clockwise of the failure point, forming an electrical loopback from an OSC unit coupled to the second ring to an OSC unit coupled to the first ring; and in a second node of the network that is immediately counterclockwise of the failure point, forming an electrical loopback from an OSC unit coupled to the first ring to an OSC unit coupled to the second ring.