First and foremost are the cost savings of Internet VPNs when compared to traditional VPNs. A traditional corporate network built using leased T1 (1.5 Mbps) links and T3 (45 Mbps) links must deal with tariffs that are structured to include an installation fee, a monthly fixed cost, and a mileage charge, adding up to monthly fees that are greater than typical fees for leased Internet connections of the same speed.
Leased Internet lines offer another cost advantage because many providers offer prices that are tiered according to usage. For businesses that require the use of a full T1 or T3 only during busy times of the day but do not need the full bandwidth most of the time, ISP services, such as burstable T1, are an excellent option. Burstable T1 provides on-demand bandwidth with flexible pricing. For example, a customer who signs up for a full T1 but whose traffic averages 512 kbps of usage on the T1 circuit will pay less than a T1 customer whose average monthly traffic is 768 kbps.
Because point-to-point links are not a part of the Internet VPN, companies do not have to support one of each kind of connection, further reducing equipment and support costs. With traditional corporate networks, the media that serve smaller branch offices, telecommuters, and mobile works—digital subscriber line (xDSL), integrated services digital network (ISDN), and high-speed modems, for instance—must be supported by additional equipment at corporate headquarters. In a VPN, not only can T1 or T3 lines be used between the main office and the ISP, but many other media can be used to connect smaller offices and mobile workers to the ISP and, therefore, to the VPN without installing any added equipment at headquarters. A company's information technology (IT) department can reduce wide-area network (WAN) connection setup and maintenance by replacing modem banks and multiple frame-relay circuits with a single wide-area link that carries remote user, local-area network to local-area network (LAN–to–LAN), and Internet traffic at the same time.
VPNs can also reduce the demand for technical support resources. Much of this stems from standardization on one type of connection Internet protocol (IP) from mobile users to an ISP's POP and standardized security requirements. Outsourcing the VPN to a service provider can also reduce your internal technical-support requirements, because the service providers take over many of the support tasks for the network.



