When permanent dedicated connections are required, a point-to-point link is used to provide a single, pre-established WAN communications path from the customer premises, through the provider network, to a remote destination, as shown in the figure.
A point-to-point link can connect two geographically distant sites, such as a corporate office in New York and a regional office in London. For a point-to-point line, the carrier dedicates specific resources for a line that is leased by the customer (leased line).
Note: Point-to-point connections are not limited to connections that cross land. There are hundreds of thousands of miles of undersea fiber-optic cables that connect countries and continents worldwide. An Internet search of “undersea Internet cable map” produces several cable maps of these undersea connections.
Point-to-point links are usually more expensive than shared services. The cost of leased-line solutions can become significant when used to connect many sites over increasing distances. However, there are times when the benefits outweigh the cost of the leased line. The dedicated capacity removes latency or jitter between the endpoints. Constant availability is essential for some applications such as VoIP or video over IP.