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Local IP Access (LIPA) and Selected IP Traffic Offload (SIPTO) are two topics currently of high interest to mobile network operators. They enable data traffic offload at appropriate points in the Radio Access Network in a highly cost-efficient manner. These technologies also have the potential to greatly increase system scalability and offer operators the flexibility to cope with the growing community of smart phone users and the associated increase of mobile data traffic. This paper first introduces the main concepts behind LIPA/SIPTO and discusses the main requirements to support them. Different architecture solutions, proposed for home, enterprise and macro-cellular networks, are presented. The paper also elaborates on LIPA/SIPTO traffic handling. A DNS-based approach, offering operators a fine-grained control of LIPA/SIPTO traffic handling, is introduced. The paper then discusses different other issues pertaining to LIPA/SIPTO traffic management, SIPTO QoS support, data offload gateway selection, and service planning and deployment. Finally, the paper concentrates on recent efforts towards the support of LIPA/SIPTO service continuity.