VPN+-+Applications+&+Technology


 * Applications of VPN Services and Technology**

Figure 3 below models two traditional types of data connections, dedicated connectivity and dial-up networking (also referred to as remote access). Dedicated connectivity in the U.S. is typically in the form of a T1 connection (1.544Mbps), fractional T1 (NX64kbps), or 56kbps service. These connections have an access component (FCC Tariff 11) and a Private Line component (FCC Tariff 9). The access component is the transmission line from the customer facility to the Bell operating company's central office (CO) and the private line component is the "long-distance" carrier facility. The pricing for each of these components is typically distance sensitive. In other words, the longer the circuit the more it costs. This distance sensitive pricing model is very similar to the dial-up environment, also depicted in figure 1.1. Local phone calls are essentially free after paying a flat rate for local telephone service (e.g. there is no additional cost on a per call basis for local calls). However, we pay some amount per minute above our basic service fee for long distance. Furthermore this per minute charge varies based on where you are calling.

**Figured 3 : Dedicated Connectivity**

As we look at figure 4 below, we see three very interesting advantages to introducing a shared network transport and VPN services. First the "long-distance" component of the dedicated service is eliminated and replaced by the shared VPN service. Second, the dial-up connections can be shifted from a long-distance or 1-800 number to a local call. The third advantage is subtler, but we have been able to move from a point-to-point to a point-to-multi-point connectivity model. This allows a facility to share a single physical access connection across many virtual point-to-point connections and allows for any user to communicate to any other user without having a dedicated connection specifically between each pair of end points.



**Figured 4 : Dial-Up Networking**

The cost savings are particularly evident in the dial-up or remote access environment, since corporate employees will be able to dial a local number to access their corporate data back at the home office. As previously mentioned, the typical method for remote access today involves dialing up to a central modem pool at the headquarters office via a 1-800 number. This can be quite expensive for companies that are widely distributed and having large mobile sales or support organizations.

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