Address allocation method, apparatus and system

Embodiment of the present invention provides a method of address assignment, devices and systems. A method suitable for a network with the Broadband Remote Access Server BRAS, with carrier-grade network address translation on CGN BRAS, comprising: BRAS local fault detected CGN provided; BRAS receiving an access request sent by a terminal; BRAS assigned to the terminal public IP address. Example embodiments of the present invention, when implemented in a terminal without failure CGN traffic transfer, shorten the service terminal when the BRAS CGN fault recovery time and reduce costs.