I was "happy" with my dial-up 56K modem internet access, but some accesses were so slow that my family decided that we should try a cable modem.

Basically, and usually on weekends, my dial-up internet connection was so slow that it was totally un-useable. For instance, signing in to a free email account required more than 30 minutes. (Yes, I know that dial-up modems are slow, but that is NOT the problem here.) During non-peak hours, access was instantaneous - maybe 20 seconds. And while some sites never loaded, other sites were still available at the same speed as before.

At any rate, my family decided that we should try a cable modem.

Comcast was the only high speed internet option (Northern Virginia).

The sales person said that all we needed was a Cable Modem and that it would support up to 4 computers. Well, that was wrong - you can only plug in one computer. If you want to support more, you must provide some form of address translation.

Each computer on your network has its own IP address. The Cable Modem has 2 IP addresses - one for your network and the second to talk to your cable provider. The address translator converts a local network address to the internet address so that only the internet address is seen to the outside world.

This can be accomplished using one of the following.

• A Proxy server
• NAT (Network Address Translator)
• A Router

This is great - This is good - This beats DSL

• Pricing - available if you already have cable, but not available if you ONLY want internet

Recently, Comcast was bought out by AT&T - so I tried their web site. Another waste of time with no useful information.

I guess persistence counts - I eventually found a list of supported cable modems (it was under FAQs).

Well, I finally got some answers at www.comcastonline.com - you would think that the original comcast page would have a link to here. Instead, I had to read most of the FAQs to find it. ($55/month)

I can not determine if there is an extra charge for a fixed IP address.

There are basically 2 ways to provide address translation

• Attach the cable modem to a computer which has a separate net card connected to the local network. This computer must run the NAT (Network Address Translator) software, which I think is just a generic name for a Proxy server.
• Use a stand alone dedicated computer, called a Router, to perform the address translation. Most of the routers available locally are combined with a Switch which allows the connection of several computers.

• The cable connects to the cable modem
• The cable modem connects to either the Router or a PC
• The Router (or PC) connects to your LAN

www.howstuffworks.com provides a very good description of address translation (NAT).

Windows XP
SMC EZ Card 10/100 PCI (SMC 1211 Series)
Linksys Cable Modem with RJ45 and USB capability
The XP system was already connected to a network that accessed the internet
  via a dialup modem on another machine

Oh, the cable modem could see the internet ok (verified using ipconfig and the modem's lights), but Internet Explorer and ping could not.

The cable modem was plugged into the USB port, and I had the computer connected to a local network with a network card (NIC). I could see the local network fine, but not the internet.

After several hours of work, I found that when I disabled the network card (via the control panel), Internet Explorer and ping accessed the internet without problems ... but I could no longer see the computers on the network.

The solution was to enable ICS (Internet Connection Sharing).

When ICS (Internet Connection Sharing) is enabled, XP tries to set the network card to 192.168.0.1 - there are no options, that is the only possible address.

Well, the existing network shared the internet through a dialup modem on another computer which already had that address. My plan was to leave the system with the modem at that address and to give the XP NIC another address. (I want to keep the dialup connection so that I could still have internet access when the cable system is not available.) You guessed it, I had to change the other computer's address.

After ICS was enable, all the computers on the local network were able to use the cable connection to access the internet and the XP system was able to see the local machines.

Cost - about 6 hours, 11 counting additional research and testing after it "worked".

• I started this process December 11, 2002
• I called the cable company December 15, 2002 to arrange for installation (according to their records).
• In January, after I called to see what was happening, a contractor came out and placed a cable in a trench. This cable was not attached to the house or a pole.
• On Monday, February 3, 2003, another contractor showed up at 6:30 PM (without calling first) "to verify that everything was complete and working". He placed a box on the back on the house and connected the cable to the box. I was told that someone would be out the next day to attach the cable to the pole.
• On Monday, February 10, 2003, I called the local government (the Board of Supervisors) and explained the situation. They contacted the cable company and scheduled completion for the next day.
• The cable was finally connected from the pole to the house February 11, 2003.
• I told the installers that I preferred to do my own inside wiring (through the attic and down the walls) and they said that they would return at 3:30 PM the next day to crimp on the connector.
• I called each of the next 2 days (no show, no call). Finally, I decided to "terminate" the inside cable myself and finish the setup on my own.
• It worked for the first time Thursday, February 13, 2003.
• I still don't have any information on how to use email. (My other accounts require me to dial in to them to send mail, reading mail is not a problem.)

Allowing for Christmas and several snow storms - 2 months is still too long.

About a month ago, we added a router to the network and removed the Windows XP machine from the path (we originally used it as the router, but it hangs on a regular basis and would keep the other machines from reaching the internet).

• Telnet failed from 2 machines - Windows 98 and XP.
• I verified that http, ftp, and email (both send and receive) worked ok.
• I reconfigured the network to remove the router. Now the cable modem plugs directly into the XP's USB port.
• Telnet still fails - the other protocols are ok.
  The error is "Connection to host lost."
• I emailed tech support for the site I was trying to telnet to - at least one person uses Comcast and is currently not having a problem.
• I tried another machine using a dial-up modem - telnet works fine.
• I tried another telnet server and it fails the same way.

After 2 days of trouble shooting and/or waiting for the problem to fix itself, I called Comcast (the ISP). They flatly refused to talk to me - telnet is not handled by their technical support. I tried their "live chat" support, and they said that Microsoft would have to solve the problem. Specifically, they "were not licenced to support third part software".

I called Linksys (the cable modem manufacturer) - they said that as long as http, ftp, and pop3 were working, there was no way that the modem could be the problem - it just passes the packets, it does not contain a firewall or any kind of filtering capability.

I tried PortQry.exe to test port 23 (telnet)

C:\DOWNLO~1\PORTQRY\EXE>portqry -n cpcug.org -e 23

Querying target system called:

 cpcug.org

Attempting to resolve name to IP address...

Name resolved to 216.255.136.62


TCP port 23 (telnet service): LISTENING

Princeton terminates telnet sessions in this manner for security reasons if the IP address is not properly registered.

8 hours later, it fixed itself. At 9:00 am it was broke, at 5:30 pm it worked. That's right, nobody took responsibility for the problem, it just went away on its own.

My best guess is that is was the cable company's problem.

• 2 telnet servers would not work
• 2 of my machines failed, using different operating systems
• Another Comcast customer was not having a problem
• The problem fixed itself

Of course, there is another possibility - another computer could have sent intentional disconnect messages to my system.

• Many cable modems have a diagnostic address located at 192.168.100.1 This will give you the firmware version, power levels, SRN, error log, configuration file, and much more. (I've tested this with Linksys BEFCMU10 ver 2.)
• When cable modems boot, they read a configuration file from your ISP. The files contain names like copper, bronze, silver, and gold (levels of service)

On your Windows XP system, look at

%SystemRoot%\System32\Drivers\etc\Services

URL: http:// cpcug.org / user / clemenzi / technical / Upgrades / Cable_Modem.html