dacs.doc electric

 

The Cable Modem Won't Work
or Wow, that Lightning was Close!

by Jim Scheef

 

Almost exactly one year ago last summer, a lightning storm knocked out my cable modem. What follows is a recount of my trials to get things working again. Along the way, I’ll give some hints on dealing with Charter Communications, from whom I get my cable modem Internet service.
Now, this was not your run of the mill lightning storm that gives a few rumbles and sends the dog hiding in the bath room. This was a big storm, with lots of wind blowing tree branches down and scattered power outages. Perhaps unfortunately, my house never lost power. If I had been home, I might have pulled the plugs out of the wall--the ultimate surge protector.

However, when I did get home, the cable modem could not get an IP address. Since the cable television was working, I called the Charter phone number in the New Milford phone book. This was mistake #1, because this is the general number for all cable TV questions. Because of the storm, many people were experiencing trouble, so after a long hold, I was transferred to another hold queue to wait for someone in the Internet dept. [Hint: The phone number for the Internet Department is 203-426-6116. Call this number directly]. Once I was talking to a real person, it turned out to be a very helpful technician, who determined that my cable modem was damaged. The jolt had to have come in thru the cable TV cable, as every piece of equipment in my ‘data center’ is on an uninterruptible power supply (UPS) or a high quality surge protector. Even the LAN has a grounded surge device. Because of the holiday, they could not do the exchange until sometime after the 4th of July. At least this was not a long holiday weekend! On Thursday, I drove over to Newtown and made the swap.

Once I had the new cable modem, it would not ‘link’ to the router when plugged into the WAN port. Most ethernet equipment has a light that comes on when the device has a valid electrical connection to another device. This meant that the WAN (wide area network) port on the router had also been damaged by the lightning. Arghhh!

So I called SMC Networks, which manufactures the Barricade router. They have 24hr tech support, with knowledgeable support technicians. The pleasant woman at the SMC showed me how to do a "hard reset" of the router. This questionable design feature requires shorting two pins of the serial port and powering on the router. This task requires three hands and did not cure the problem. I opted to pay for overnite shipping of the replacement.

While waiting for the router, I needed to reinstall the ‘official’ NIC (network interface card) first used to install the cable modem. All ethernet cards have a unique number called the media access control (MAC) address burned into them at the factory. This NIC has the magic MAC address that identifies me to Charter's DHCP (dynamic host configuration protocol) server, so it will assign me an IP address. This exact card would be needed to program the new router so the router can fool Charter’s server into thinking it is talking to the "official NIC". Got that?

Well, naturally, installing the card required debugging to avoid resource conflicts--both IRQ and i/o port in an old pre-plug and play PC running Windows NT. This was probably why I had pulled the card out! At least this gave me something to do while I had no Internet access.

By the time I got the NIC working, the router had arrived and I still could not get an IP address from Charter. Another call to Charter Internet support and this time the technician suggested that I reset the cable modem. This was easy to do, using a paper clip in a small hole. Within seconds the cable modem lights started flashing, and by the time I could check, I had an IP address. What an effort!

So what did I learn from all this? Whenever your cable modem stops responding, give it a kick in the rear by unplugging it for a minute. Turn off the router as well (tell Charter it’s a PC) and turn them back on together. This will clear up most trouble caused by problems in Charter’s equipment. If you tell Charter you have a router, they will tell you to connect the cable modem directly to the PC. This is almost never necessary; they just don’t want to support routers that they do not provide, which I guess is fair.

So, why use the router at all? Why not just connect the cable modem to the PC the way Charter wants you to? The short answers are "fire wall" and "convenience." You need something to keep the bad guys out. There are many software products on the market that do an admirable job keeping the bad guys at bay, but a hardware router, like products from SMC, D-Link, Linksys and many others, are easier to configure and allow you to securely share your DSL or cable modem connection with the other computers in the house. The convenience side comes from the fact that the Internet Connection Sharing built into Windows ME, 2000, and XP requires the PC to be on if the other computers need internet access. With a router, every computer is connected to the router, so only the PC in use at the time needs to be on. Makes sense, eh?


Jim Scheef is the Mad Scientist at Telemark Systems Inc. where he develops custom software using Visual Basic and SQL Server and provides networking services using Windows NT/2000. He has been a DACS member since the day DOG became WC/MUG..

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