A point-to-point link provides a pre-established WAN communications path from the customer premises through the provider network to a remote destination. Point-to-point lines are usually leased from a carrier and are called leased lines. Leased lines are available in different capacities. These dedicated circuits are generally priced based on bandwidth required and distance between the two connected points. Point-to-point links are generally more expensive than shared services such as Frame Relay. The cost of leased-line solutions can become significant when they are used to connect many sites. There are times when cost of the leased line is outweighed by the benefits. The dedicated capacity gives no latency or jitter between the endpoints. Constant availability is essential for some applications such as electronic commerce.

A router serial port is required for each leased-line connection. A CSU/DSU and the actual circuit from the service provider are also required.

Leased lines are used extensively for building WANs and give permanent dedicated capacity. They have been the traditional connection of choice but have a number of disadvantages. WAN traffic is often variable and leased lines have a fixed capacity. This results in the bandwidth of the line seldom being exactly what is needed. In addition, each end point would need an interface on the router which would increase equipment costs. Any changes to the leased line generally require a site visit by the carrier to change capacity.

Leased lines provide direct point-to-point connections between enterprise LANs and connect individual branches to a packet-switched network. Several connections can be multiplexed over a leased line, resulting in shorter links and fewer required interfaces.

Interactive Media Activity Checkbox: WAN Technologies Leased Lines Upon completing this activity, the student will be able to identify the characteristics associated with a leased line connection.