Provided are a communication method and apparatus, and a
system, relating to the technical field of communications. The method is executed by a communication apparatus in a network
system. The method comprises: determining that a first internal gateway protocol (IGP)
network topology is a stable topology; generating a first IGP path on the basis of the first IGP
network topology; and upon generation of the first IGP path, on the basis of a
routing protocol fault occurring on a second IGP path, switching the second IGP path to the first IGP path, wherein the second IGP path includes a path from a first communication apparatus to another communication apparatus. The first IGP path includes a path from the first communication apparatus to another communication apparatus, and the second IGP path includes a path from the first communication apparatus to another communication apparatus. In this way, by means of path fallback, it is ensured that a network is restored to a stable topology state capable of normal communication, a
routing protocol fault caused by problems such as routing oscillation and the introduction of routing configuration errors can be solved, thereby improving the universality of
network recovery.