Making WAN Connections
Private or Public?
A private network is one that is exclusive to a particular company. No other company's
data is sent over the private network. The advantages are that the data is secure, you
can control how the network is used, and you can predict how much bandwidth you
have available. A public network (or external network), such as the Internet, is a network
through which many companies' data passes. Public networks are less secure than
private networks, but the advantages are that public networks are less expensive to use
and you don't need to maintain the external network yourself.
Use a public network under the following conditions:
You don't care if data occasionally takes longer to reach its destination or if the
delay between sites is relatively unpredictable.
You want the lowest cost network connection possible.
The data does not need to be secure or you have the ability to make it secure
over the public network. (Technologies such as virtual private networks or
some types of data encryption can provide such security.)
Use a private network under these conditions:
Data security is of utmost concern.
You have a large, experienced staff to set up and maintain the public network.
Cost is unimportant relative to the benefits that the network brings.
You need full, reliable control over the network's bandwidth use.
Comparing WAN Connection Types
Now that you understand some basics of WAN links, the remainder of this chapter
provides an overview of the available WAN technologies, ranging from telephone
connections to very high-speed, high-bandwidth connections.
Plain Old Telephone Service (POTS)
Plain old telephone service (POTS) is the telephone service everyone knows. While
it does not technically qualify as a WAN connection (at least as most people think
of WANs), POTS can still serve to link two or more sites together for certain low-
bandwidth needs. Although it is among the slowest methods of establishing a network
connection, POTS is ubiquitous and easily used throughout the world.
POTS is carried over one set of twisted-pair wires (in other words, just two wires).
In some cases, two sets of twisted-pair wires are used, but only the two main wires
carry the telephone signal and ring signals. The other two wires are used for other
features, such as backlighting a keypad on a phone or providing a message-waiting
light with some PBX systems. POTS connections currently use RJ-11 telephone jacks,
which simply snap into place.