Generally, VPNs are used for one of the following three main reasons: to interconnect two or more company locations via a public network (site-to-site VPN), to remotely access the company network when traveling or from home (end-to-site VPN), or to remotely access one computer from another computer (end-to-end VPN).
Site-to-Site VPN : A site-to-site VPN is used when multiple local networks are to be connected to a virtual communication network, via a public transport medium. Such scenarios are possible, for example, when connecting different company locations with one another. Alternatively, location networks can also be realized, in the form of a corporate network. Corporate networks are based on a private fixed connection, but companies have to rent the corresponding infrastructure first in order to use it. A connection via VPN, on the other hand, relies on a public network. Here an internet connection is the only cost involved. Creating a site-to-site VPN also requires a VPN router; these are needed to build the connection between the VPN tunnel and the local network. Other terms used to describe a site-to-site VPN include: LAN-to-LAN or Branch-Office VPNs.
End-to-Site-VPN : Companies tend to use end-to-end VPNs whenever their networks are to be made available for mobile users working in the field of from their home offices. The tunnel to the local network is created through a VPN client on the external employee’s terminal device; here the main transport medium is also the internet. This enables employees to access the company network (and so any file and mail server located within this) simply via internet connection. An end-to-site VPN is also referred to as a remote-access VPN.
End-to-End VPN : And end-to-end VPN occurs if setting up a network with remote access isn’t possible, and can only be done by connecting one computer to another one. Working on a remote desktop would be a classic use case for this kind of VPN connection. Here, a software program is executed on one computer, and displayed and used on another one. The transport medium for such applications can be the internet or a local company network. For business-related purposes, remote desktop VPNs are used when an employee seeks to access their work computer from home.
