Point-to-Point WAN Links (Leased Lines)

The terms “point-to-point link” and “leased line” refer to the same thing when describing WAN connections – a dedicated link through the service providers’ network. This link is not shared with other customers, and provides a dedicated circuit between two locations. This isn’t to say that the link is a single physical wire. In reality, it is a permanently established circuit through the service provider’s switched network, similar to what is illustrated in the figure below.

Figure: Two offices connected through a service provider’s network using a leased line.

A leased line is a good choice for customers who require consistent bandwidth between two locations. The speed of these dedicated links can vary – for example, a customer may choose a 64K leased line, or one at T1 speeds or higher. Leased lines are generally more expensive than other WAN connections, since the link is permanent and dedicated to the customer, regardless of the extent to which they use their allocated bandwidth. In other words, if a customer pays for a 128 Kbps leased line and then averages only 64 Kbps usage, they still pay for the full bandwidth that the link provides. Prices for leased line vary according to required bandwidth, and sometimes distance between locations. Leased lines will typically use either the Point-to-Point Protocol (PPP) or High Level Data Link Control (HDLC) protocol to encapsulate and send data between locations.

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of 2000Trainers.com. He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.