Connect Your LAN To The Internet Using ADSL

You have no doubt heard the World Wide Web described as the World Wide Wait! Well I recently had Asymmetric Digital Subscriber Line (ADSL) service installed at my office to gain higher speed access for less cost than my ISDN connection. There are other options out in the market for high-speed access to the Internet. This article covers my experience with the installation and connection of my ADSL service. I have also tried to give a comparison of ADSL to some of the other services available in the area. Installations of ADSL service just began in the St. Louis area the second week of July and Symmetric Digital Subscriber Line (SDSL) service is already being installed in the area as well. ADSL uses your existing telephone line to provide you with high-speed download with lower speed upload to the Internet. ADSL service is geared toward users who pull a lot of data from the web and do less uploading. Most home users and small businesses would fall into this category. Cable modems are usually configured very similar to ADSL. Cable modems usually have higher speed downloads than uploads. Therefore, if you need to have high-speed access in both directions such as wanting to setup your own web server or hosting service, you should look into SDSL service or some other dedicated line type service. SDSL service provides the same high-speed access to the Internet in both directions (upload and download). The current limits that I have seen for SDSL is 1.5Mb/s in both directions but remain constant. There are several companies in the St. Louis area offering SDSL and only a few reseller partners selling ADSL. Southwestern Bell installs the ADSL service onto your phone line. Then you must choose an Internet Service Provider that is reselling the ADSL service to connect with. SDSL service is sold directly by several Internet Service Providers in the area. Your cable company provides Cable modem service. Most cable modems so far have been configured to use a dial up access to send the request for the web pages to download and the data is then downloaded to your computer via your cable company’s wiring. However, in some areas there is two-way cable modems that provide both upload and download streams across the same cable. This is a much faster configuration. However, the technology in this article for connecting your Local Area Network to the internet can be applied to most of the Internet access technologies available today. In fact it can even be applied to dial up service as well.

I had my order in for installation the first week of July and it wasn’t installed until August 13. This gives you an idea of the lead-time for getting ADSL service installed. ADSL service is being offered in two flavors in the St. Louis area. The slow version supports 384Kb/s – 1.5Mb/s download speeds with a 128Kb/s upload speed and costs $39/month for the ADSL service and between $10 - $40/month for your ISP depending on home or business services. The faster version supports 1.5Mb/s – 6Mb/s download speeds and 384Kb/s upload speeds and costs $129/month for the ADSL service and $70/month for your ISP. Your ADSL performance will vary depending on the quality and wire distance of your phone line to the Central Office (CO). If your line qualifies you are guaranteed that it will meet the lowest speed for the range you selected. For the St. Louis area there is a $199 installation charge to have ADSL service installed into your home or business. This installation charge includes a Plain Old Telephone Service (POTS) splitter, an Ethernet Network Interface Card (NIC) and an Alcatel 1000 ADSL modem. You must qualify your phone line before you can have ADSL or SDSL service installed. Therefore not everyone in the St. Louis area has access to ADSL or SDSL at this time since both ADSL and SDSL have the same limitations. To find out if your line qualifies for ADSL service you can call SWB at 1-888-792-3751. SWB is working on new technologies to get past these current limitations to provide wider access to DSL type services. It is in their best interest to have customers on ADSL since it doesn’t tie up extra switches and cable pairs to get access to the Internet.

When the installer tested the phone line at my office, it was only 2600ft from the CO and it qualified at 6.1Mb/s. However, the line is throttled back to 6Mb/s for the high speed service in the Digital Subscriber Loop Multiplexer (DSLAM) equipment at the CO. Unfortunately, my home phone line didn’t qualify for ADSL service because it was past the 17,500 foot wire limit. You must choose an ISP for your ADSL connection and SWB isn’t the only company offering ADSL ISP services at this time. There are several Internet Service Provider Partners reselling ADSL service and they are a few dollars cheaper than SWB. These providers can be found at the SWB web site at Click on the icon for DSL service and then the Internet Service Provider Partners to find out more.

An article in the May issue of PC Journal provided a good technical description of how ADSL works so I won’t cover all of the details here. ADSL uses your existing phone line for both your voice calls and your ADSL data connection. This allows you to dial and receive phone calls while you are connected to the Internet using ADSL. ADSL service is actually added to your existing phone line by splitting the phone line at your home or office using a POTS splitter. From the splitter your voice line is connected to the circuit as it was before and an ADSL phone jack is installed for your ADSL modem to be connected to. This modem has an Ethernet connector on it, which must be plugged into an Ethernet card in a PC, an Ethernet router or an Ethernet hub. Your ADSL service provides you with a dynamic IP address for residential service and a static IP address for business services for the internet. Your ADSL modem is constantly connected to the internet, unlike using a dial up modem to establish a connection to the internet.

Getting detailed information about connecting a Local Area Network to the Internet using ADSL service was rather difficult. SWB is a phone company and not a networking company. Therefore, they currently will only connect an ADSL modem to your PC and not to a network. Therefore connecting your network to the Internet via ADSL is up to you or you can hire a consultant to get your network connected. My goal was to acquire an ADSL router from SWB rather than the standard ADSL modem, so I wouldn’t have to purchase an additional hardware firewall/router or setup a PC to run firewall/routing software. I have described several of the methods below to get your Local Area Network connected to the Internet using your ADSL connection. I also briefly mention some of the security issues to be concerned with when connecting to the Internet using ADSL.

ADSL Modem Connected to a Single PC
This is how SWB will hook your PC up to the Internet on an ADSL line at this moment in time. I have talked to several people at SWB trying to get an ADSL router and there hasn’t been any confirmation as to when or if they will eventually be offering a router for hook ups as well. For the moment though, if you want to have more than one PC hooked up to the Internet using your ADSL phone line you will have to implement that solution on your own or hire a consultant to do it for you. If you are in the St. Louis area and you want to purchase your own ADSL equipment when other equipment becomes available, you must purchase equipment based on the Dynamite chip set for compatibility with SWB equipment.

Some choices to getting Multiple PC’s onto the Internet using ADSL

  1. Use an ADSL router instead of the ADSL modem.
  2. Plug your ADSL modem into an Ethernet to Ethernet router.
  3. Install a second NIC into your PC and plug that second NIC into your Local Area Network Hub.
  4. Plug your ADSL modem into your Local Area Network Hub directly using a crossover cable or using a crossover port on the hub (the Alcatel 1000 ADSL modem has a built in crossover connection).

ADSL Router Solution
Unfortunately at the time my ADSL installation, I could not locate any ADSL routers that were shipping with the Dynamite chip set which is require by SWB’s DSLAM equipment. Alcatel does have an ADSL router that should be available sometime in September. It was originally slated for May 99 but was delayed. If this ADSL router is reasonably priced this would be the most desirable solution to connect your network to the Internet. It provides Network Address Translation so you can use Non-Internet Routable IP addresses behind the router such as This router would save the expense of purchasing both the ADSL modem and an Ethernet to Ethernet router.

Ethernet to Ethernet Router Solution
This solution works the same as the ADSL Router Solution with the exception of an extra piece of equipment having to being purchased. Netopia offers an Ethernet to Ethernet router, which costs approximately $600 - $800 street price. You would plug one Ethernet connection on the router to your LAN Hub and the other Ethernet connection on the router to your ADSL modem.

Second Network Card Solution
This solution is a little more expensive than any of the hardware only router solutions since you will be tying up a PC for routing network requests to the internet. This solution involves installing a second Ethernet card into the PC that is connected to the ADSL modem. Then you must install and run a software program to run as a Firewall/Router between the Ethernet card connected to the ADSL modem and the Ethernet card connected to you LAN. The software routes all desired packets from the Internet coming from the ADSL modem to the second Ethernet card connected to your LAN. You can allow or disallow certain addresses or services through the firewall.

ADSL Modem Direct Connect to Hub Solution
This solution puts your computers at risk to security threats from outside users on the Internet since it requires you to enter in the IP addresses provided to you from your ADSL ISP for each of the PC’s on your LAN. It also limits you to the number of PC’s that can be connected to the Internet by the number of IP addresses provided to you. The standard business package only provides you with 5 IP addresses to be used for hooking up to the Internet whereas a router can provide nearly an unlimited number of PC’s to be connected.

Security Issues
Security issues should be considered anytime that you are connected to the Internet. With dial up Internet access your IP address usually changes each time you log in. However, with ADSL your IP address is usually static and therefore you are more exposed to intrusions since you are connected all the time. If you are running Windows 9X/NT with file sharing you are definitely taking a risk with your PC’s data. You can disable file sharing and that will reduce the risk of intrusion but not completely. Firewall software is available for your PC and can be downloaded from various sites. For links to specific routing software sites please visit my web site at I have tried several different ones and they work fairly well. However, they cost nearly as much as a hardware router and you have a PC tied up.

I went to to check the performance of my ADSL line after it was installed. This web site has a link to do performance testing by timing the download of either text or graphics data to your PC. After the test is complete, it then displays a performance results page displaying your results and a comparison between a 33.6K, 56K, ISDN 64K and ISDN 128K service. I currently have the low-speed ADSL service and I was getting anywhere from 486Kb/s to 890Kb/s from Your performance can vary greatly depending on what’s happening on the web and the traffic at each particular test site at the time you perform the test. For example, I posted a video clip on my web site that was approximately 5MB. It only took 39 seconds to download using ADSL as opposed to 35 minutes on a dial up modem connection. This is a significant improvement over dial up.

I’m out of room for all the information I wanted to provide you with so visit my web site at to find out more information and other links on DSL technologies. I also have some detailed setup notes for hooking up your LAN using ADSL that I didn’t have room for. Hopefully, you can get access to one of the higher speed access services available in the area for the speed you need.

Rich Simpson is president of Mind’s Eye, Inc., a software development and IT consulting firm. He has a degree in aerospace engineering and has been designing and developing custom and commercial database applications since 1986. For more information or to download software demos visit their web site at or send e-mail to or call 636-282-2102.



Copyright 1999-2008 Mind's Eye Inc.
Last modified: March 02, 2009