Ip address acquisition method and a network access device

Embodiment of the invention relates to a method for obtaining the IP address and network access device, a first identifier comprising a first IP network address acquired by the network access device after receiving a request message to the first network via a process of the first assign a network identifier associated with a first IP address and the first network and the first session, the first IP address mapping for a first private network IP address; and transmitting said first private IP address to the first network can avoid implementing complex problems of the prior art due to the home network gateway or enterprise network configuration required to initiate the process which led to IPoE dial, simplifying the home network gateway or enterprise network configuration, and reduces operation and maintenance costs, achieve further a flat network.