Once connected, the tunnel peers can exchange information and access servers and services from either end of the virtual link. Authentication is often the most important security element in multiprotocol IP tunneling. It ensures that tunnels can only be established between verified tunnel peers. Different tunneling protocols approach the issue of authentication in different ways. In contrast, other popular tunneling protocols rely on PPP authentication routines to verify tunnel requests.
Authentication occurs before the connection is established.
Once the connection has been established, encryption is used to authenticate the link. The emergence of the Internet as the number one source of information, coupled with the increase in online voice and data communications, has made electronic commerce and Web-based business solutions enormously appealing. Additionally, the telecommuting phenomenon has created a need for low-cost, secure, reliable access to corporate networks. VPNs capitalize on the requirements of the business professional in the Information Age.