Abstract: A method for obtaining a cross-domain link. The method includes: a control device sends a first message to a forwarding device in an internet protocol (IP) domain, where the first message is used to instruct the forwarding device to search for a device adjacent to the forwarding device in an optical domain; the control device receives a second message from an optical network element adjacent to the forwarding device in the optical domain, where the second message includes a first identifier identifying the optical network element, a second identifier identifying a port communicating with the forwarding device and being on the optical network element, and a media access control (MAC) address of the forwarding device; and obtains the cross-domain link between the forwarding device and the optical network element based on the first identifier, the second identifier, and the MAC address of the forwarding device.

Abstract: This application describes a fault protection method for an optical network. A cross-layer controller connecting an optical network and an IP network sends, to an optical controller in the optical network, an indication that a first optical service in an optical fiber belongs to a first priority and a second optical service in the optical fiber belongs to a second priority. The first priority is related to a feature of the first IP link in the IP network, and the second priority is related to a feature of the second IP link in the IP network. When the optical fiber is faulty, a protected priority of any optical service belonging to the first priority is higher than a protected priority of any optical service belonging to the second priority.

Abstract: A method for obtaining a cross-domain link. The method includes: a control device sends a first message to a forwarding device in an internet protocol (IP) domain, where the first message is used to instruct the forwarding device to search for a device adjacent to the forwarding device in an optical domain; the control device receives a second message from an optical network element adjacent to the forwarding device in the optical domain, where the second message includes a first identifier identifying the optical network element, a second identifier identifying a port communicating with the forwarding device and being on the optical network element, and a media access control (MAC) address of the forwarding device; and obtains the cross-domain link between the forwarding device and the optical network element based on the first identifier, the second identifier, and the MAC address of the forwarding device.