The technology of this application relates to a communication method that includes a gateway obtaining first information, sending, to the first node, an access protocol message (for example, an EAP-5G message or an SLAP message) that carries the first information, where the first information includes one or more of information that indicates an integrity protection algorithm, information that indicates an encryption algorithm, an integrity protection key, or an encryption key; and exchanges communication information with the first node according to GTP-U based on the first information, where the gateway belongs to a second communication system, and the first node belongs to a first communication system. The gateway and the first node may implement security and/or integrity protection on the communication information based on the first information.