An SFC-based communications method and system, and an apparatus are provided. The SFC includes a CF node, an SFF node, and an SF node, and the SFF node is connected to the SF node. The method includes: receiving, by the CF node, a first message from the SFF node; obtaining, by the CF node, network topology information of the SFC based on the first message; obtaining, by the CF node, an SFC forwarding table, where the SFC forwarding table is determined based on the network topology information of the SFC; and sending, by the CF node to the SFF node, a second message used to indicate the SFC forwarding table. In this way, a network topology of the SFC can be flexibly and efficiently discovered.