Protection method and system for multi-domain network, and node

A node, comprising a detecting unit, a switching unit, and a processing unit, wherein:

• the detecting unit is configured to detect a failure of a first link, wherein the first link is a link between a first node and the node;
• the switching unit is configured to:
• after it is detected that the first link fails, disconnect a first protection path on the node, and connect a first sub-path and a path that is within a second domain, uses the node as an endpoint, and is used to bear a service, wherein:
• the service is a service that passes through a first domain and the second domain;
• the first domain and the second domain intersect at the first node and the node;
• the first protection path is formed by splicing the first sub-path and a second sub-path and is a protection path of a first working path;
• the first working path is a working path of the service between the first node and a third node within the first domain;
• the first sub-path is a path between the node and the third node;
• and the second sub-path is a path that passes through the first link and is between the first node and the node;
• and
• the processing unit is configured to:
• after it is detected that the first link fails, send, on the first sub-path, a first failure monitoring message that carries first maintenance information to the third node, wherein:
• the first maintenance information is the same as second maintenance information carried in a second failure monitoring message;
• and the second failure monitoring message is a message that is sent on the first protection path by the first node to the third node and is used to monitor a failure of the first protection path.