Digital Private Lines
A digital private line, also called a data line, a
point-to-point tie line or a circuit, is a dedicated physical connection between (2)
locations.
A private line is like a chain between (2)
locations, consisting of (3) links. The two end links are the local loops, which are
provided by the local telephone companies (LEC). These local loops are the first and third links and connect the
customer locations to the long distance carrier. The second, or
middle link, is the long distance or inter-exchange (IXC) connection, which is provided by
the long distance carrier (MCI or Qwest).
The speed of digital private lines can vary from as
low as 56,000 bps to as high as 45 Mbps (DS-3). Typically, point-to-point data lines are
now 1.536 Mbps (T-1). A point-to point T-1 will typically be 3-5 times more
expensive than a 56K data line but its speed is 24 times faster than a 56K data line.
The cost of a digital private line is mileage and
speed sensitive. Two-thirds of a data line cost are the (2) local loops and are based on
the proximity of the end user location to the local telephone company office. The third
cost element is the long distance mileage between 2 locations. Therefore, as the distance
between (2) locations increases, the cost of the line increases, but not
proportionally to the increase in the distance, due to the local loop pricing at each end
remaining constant. |
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