The VPN (Virtual Private Network), is a technology that allows you to make private communications. We shall make it a private network in the form of company intranet . These networks offer two major advantages:

• Of high performances in terms of bandwidth, in other words communications in very broadband and of very high quality.
•  The safety and the confidentiality of the data.
  
  

In other words, it is today possible, thanks to these technologies, to spread its private network to all the planet. So, a commercial in movement can connect to the network of her company independently of the place where it is. At any time he can send or receive confidential data in a secure and fast way. In a similar way, two sites of the same company can be virtually combined in a single site, the interconnection between these two sites offering the same services as an intranet network.  

 There are two types different from VPN:

• The VPN IPSec on the network Public IP
  
•  The VPN MPLS on a network Private IP                                                                                                                                                                                                                                                                                                                                                                                                       The Public VPN IP is a network leaning on Internet, whereas the Private VPN IP is a network completely accommodated by the operator.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   The Public VPN IP is a network leaning on Internet, whereas the Private VPN IP is a network completely accommodated by the operator.                                                                                                                                                                                                                We speak about encoding " point to point " when there is only a sender and a receiver (for example, the head office and a local antenna), and we speak about encoding "multipoint" when there are some (for example, the head office and the various frames(executives) in movement).   The tunnel VPN connects directly the sender and the receiver by means of the Internet classic network, preventing a third user from intercepting the data, which would besides ask to be deciphered before being able to be read.