Leased line VPNs are usually dial-up in nature and are used by companies that already have the needed multiple points-of-presence available.

Layer 2 Tunnel Protocol (L2TP) was created by the IETF to extend a PPP connection past the connecting ISP's POP, all the way to the corporate gateway. Because PPP can run different transport protocols than IP, the remote host can appear to be on the same subnet as the corporate gateway with PPP tunneling the gateway protocol under the IP protocol. Figure 2 shows one L2TP scenario, with the disparate elements of the actual network connection shown.

Figure 2