VIRTUAL PRIVATE NETWORKING MOBILE COMPUTING

In mobile communications systems, mobile units are free to move at a local, regional, national level, track international, while providing communication. With the increasing use, mobile users wish to increasingly access Internet services during their travels, the opportunities offered by these technologies has given rise to a new paradigm "?mobile computing ? Th is paradigm underlying the concept of availability or presence "in any place and at any time" certainly such mobility involves Internet and wireless technologies in a process to provide advanced services to nomadic users, however in order to be able to off er these services with satisfactory quality, you must face many challenges in relation to the reliability of services infrastructure, energy efficiency of mobile devices