So What Is DSL Anyway?

by Russ Hewitt

DSL is an acronym for Digital Subscriber Line, a general term for a digital local network loop. DSL provides high-speed connectivity for small to medium sized businesses and telecommuters. This new technology offers high-speed, dedicated connections over existing copper telephone lines. DSL is available in different types of services, including ADSL, IDSL and SDSL.

• ADSL - Asymmetric DSL service offers Full T1 download speeds (1.5Mbps) and moderate upload speeds of 384K. It requires a DSL router and your location must be within three miles of your local telephone office/switch.

• IDSL - IDSL service requires an ISDN router. This is generally used when distance is not a factor in determining availability of service. Connection speeds are limited to 144K thoughput, and the deployment of this service is not widespread.

• SDSL - Symmetric DSL service requires a DSL router. Fast upload and download speeds can reach as high as 1.1Mbps throughput in both directions. Available speeds are based on how far away you are from your local telephone office/switch.

Advantages of using DSL

DSL helps to increase efficiency, reduce download time and increase productivity. The service can be also be used for fast Internet access, to host your own web server and e-mail server, or to create a secured virtual private network to your office. Other benefits include:

• Faster Access. Speeds from 144K to 1.5Mbps

• Up to 10 times faster than ISDN and 50 times faster than a 28.8K modem

• Always on

• Dedicated connection; no dial-up process or waiting

• Secure; runs over a dedicated twisted pair copper line

• Fast uploads and downloads

• No per-minute charges

DSL vs. ISDN and Cable Modems

DSL offers comparable speeds compared to other transmission mediums, and has very distinct advantages.

• DSL vs. ISDN -- DSL has no per minute line charges since it uses regular phone lines, and you do not have to pay a separate bill to the phone company. Speeds exceed ISDN in every case, ranging from 144K to 1.5Mbps compared to a maximum of 128K on ISDN.

• DSL vs. Cable Modem - The dedicated line provides better security than cable system. Cable service can get bogged down, depending on how many users are connected, whereas DSL will always provide you with the same high-speed connection. DSL service is also more widely available than cable.

Requirements for DSL Service

The requirements depend on the type of service you are interested in. ADSL and SDSL services both require a DSL router and the installation of a dedicated phone line as well as a network interface card for each computer.

• IDSL - ISDN - DSL can use your existing ISDN lines and ISDN router. This can be a cost-effective option if you already have an existing ISDN service. Distance to local telephone office/switch is not a factor but speeds are limited to 144K.

• ADSL / SDSL - These services require a DSL router as well as a dedicated phone line. Depending on how far away you are from the local telephone office/switch will determine the available speed.

Charges for using DSL

Unlike ISDN, there are no per-minute charges for the use of DSL services. DSL uses the same phone lines that are now in use for standard voice calls.

Setup and Fees

DSL setup will be should be totally handled by your provider. You should not have to do anything more than sign the service agreement, provide space for the router and be available during installation for any questions. Setup fees can run between $250 to $400. These setup fees usually cover the installation of the DSL line and the DSL router by a qualified technician. The DSL router will be an additional cost of around $250 to $400. Also you may incur inside wiring charges of around $100 per hour. Usually this takes no more than hour, if required. Note that promotions have been running all of the time on DSL, so both the installation and/or the router costs can be waived depending on the promotion.

Typical Connection Speeds

DSL connection speeds vary somewhat with the provider but the most common offerings for business service are:

• 144Kbits

• 192Kbits

• 384Kbits

• 768Kbits

• 1.1Kbits

• 1.5/384Kbits (upload speed is 384Kbits)

How much speed do you need? Only you can determine this. Time is money and if you want your employees to be efficient then you need to give them the tools.

Russell Hewitt is president of The Connextion, a local Internet Service Provider offering DSL, ISDN and dial-up as well as web design and hosting.

This article appeared in The Business Monthly in May, 2000.