Installing a Leased Line

Acknowledgements

I would like to thank Matisse Enzer of Internet Literacy Consultants whose Internet connection is photographed in the article below.

Myth versus fact

Leased telephone lines are used to link together two locations so as to form a private wide area network (WAN) or to connect a single computer or a network of computers to packet switching networks such as the Internet. The conventional wisdom holds that leased lines are only for well-heeled corporations, that small businesses or bulletin boards couldn't possibly want or need such a connection. Even if a sysop or small business were to be wrong-headed enough to want such a connection, the "experts" maintain that installing a leased line is incredibly complicated work best left to telecommunications consultants charging $300/hour.

As is often the case, the conventional wisdom is wrong. With a little help from your Internet Service Provider, and local phone company, hooking up a leased line can be as simple as plugging in a few cables, and easier than figuring out a modem init string. In this article we'll show you how.

Getting started

The first thing you need to do before getting started is to have the leased line installed. Since 56 Kbps and T1 leased lines use four ordinary copper phone wires, which look like this:

If you have two unused phone lines (two pairs of wires) available at your location, your local carrier will not have to bring additional cable to your location. Instead, they will take the four wires, hook them up to the terminals on your switch box. Here is a picture of what it will look like:

They will then bring the wire into your dwelling, and terminate it in what looks like an ordinary phone jack:

Below is a picture of the cable than runs from the jack to your Channel Service Unit/Digital Service Unit (CSU/DSU). One of these cables will typically come with your CSU/DSU.

The CSU/DSU serves to take digital data in the format used by the router, and translate it into the digital format used by leased lines. A picture of the front view of a CSU/DSU is shown below:

Here is the back view; note the plugged in leased line cable:

A V.35 cable is used to connect the CSU/DSU to the router. This is what the female and male ends of a V.35 connector look like:

Here is the side view:

Now where does the other end of the V.35 cable go? Well, if you are only connecting a single computer, you can purchase a synchronous adapter with a V.35 interface, and plug the adapter the card into your PC. Synchronous cards (and drivers for KA9Q or PCROUTE) are available from NiWot Networks. Using synchronous cards and packet drivers, it is also possible to run software such Trumpet Winsock.

However, if you'd like to connect a network of computers to the leased line, you will need a router. Through purchase of a synchronous card, network adapter, and appropriate drivers, you can build a router using PCROUTE or KA9Q.

Although it is more expensive, purchasing a dedicated router such as the Livingston IRX-111 pictured below will provide higher reliability as well as important additional features such as support for Frame Relay, SNMP, OSPF routing, and various security features.

The Livingston IRX-111 is available for around $2000 or so, and supports Frame Relay as well as routing at up to T1 speeds, plus Thin, Thick or 10BaseT Ethernet hookups. Information on Livingston products is available at ftp://ftp.netcom.com/pub/livingston

Here is what the back of the Livingston looks like:

From left to right, note the asynchronous port; a sync/async port (set to sync here); and the choice of Thin, Thick or 10BaseT Ethernet connections.

Another alternative are the Morningstar Express 2 series routers. More information on these is available via ftp://ftp.morningstar.com/Express

When everything is connected up, here is what it will look like:

Bernard Aboba, aboba@internaut.com, last modified: 5/29/94