An information transmission method for a communications system including a gateway and a controller, wherein the gateway and the controller communicate with each other by using a wide area network, WAN, comprising: determining, by the gateway, a current operating status and a current transmission port of the gateway, wherein the current transmission port is a current communications port between the gateway and the controller, and the determining a current operating status is determining whether the gateway is currently in an initial startup synchronization state or a normal management operating state; determining, by the gateway, a first compression parameter table according to the current operating status and the current transmission port, wherein the first compression parameter table comprises at least one compression parameter determined by the gateway, and the first compression parameter table further indicates a priority of each compression parameter; and transmitting, by the gateway, information according to the Network Configuration Protocol to the controller according to the first compression parameter table by using the current transmission port, wherein the transmitting, by the gateway, information to the controller according to the first compression parameter table by using the current transmission port specifically comprises: sending, by the gateway, the first compression parameter table to the controller; receiving, by the gateway, a response message sent by the controller, wherein the response message carries a first compression parameter that is determined by the controller according to the first compression parameter table; and processing, by the gateway, to-be-transmitted information according to the first compression parameter, and sending the processed information to the controller. determining, by the gateway, a current operating status and a current transmission port of the gateway, wherein the current transmission port is a current communications port between the gateway and the controller, and the determining a current operating status is determining whether the gateway is currently in an initial startup synchronization state or a normal management operating state; determining, by the gateway, a first compression parameter table according to the current operating status and the current transmission port, wherein the first compression parameter table comprises at least one compression parameter determined by the gateway, and the first compression parameter table further indicates a priority of each compression parameter; and transmitting, by the gateway, information according to the Network Configuration Protocol to the controller according to the first compression parameter table by using the current transmission port, wherein the transmitting, by the gateway, information to the controller according to the first compression parameter table by using the current transmission port specifically comprises: sending, by the gateway, the first compression parameter table to the controller; receiving, by the gateway, a response message sent by the controller, wherein the response message carries a first compression parameter that is determined by the controller according to the first compression parameter table; and processing, by the gateway, to-be-transmitted information according to the first compression parameter, and sending the processed information to the controller. sending, by the gateway, the first compression parameter table to the controller; receiving, by the gateway, a response message sent by the controller, wherein the response message carries a first compression parameter that is determined by the controller according to the first compression parameter table; and processing, by the gateway, to-be-transmitted information according to the first compression parameter, and sending the processed information to the controller.