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how to install comcast high speed internet: a quick guide

I would generally not post about something as specific as this, but after seeing the vast amounts of confusion and misinformation that's out there on the topic I felt that my 2c in this case would be worthwhile.

Today I got cable along with Internet service from Comcast, and one of the potential that I wondered about was the setup. I've got a Linksys WRT54G for both wired and wireless routing. Most of the comments out there mentioned a process that usually included first connecting the computer directly to the cable modem, then registering it, then disconnecting it, then connecting the router configured to spoof the MAC address to that of the computer.

However, this didn't seem to make a lot of sense. While the MAC address of the cable modem does need to be registered with comcast, it seems less obvious why they would need the MAC address of the PC itself. Maybe at some point it was necessary, but as I discovered today that's no longer the case. )As a sidenote, the cable guy that did the install of the line also said that the "pc first, router later" process was a requirement... so maybe that's how this got started).

To make sure this remains a quick guide, here's what I did (as far as I can tell the procedure would be the same anywhere in the US for a Comcast high speed Internet install):

  • First, I got my own cablemodem, a Linksys BEFCMU10 since the price was equivalent pretty much to a year of renting whatever Comcast was going to give me, it seemed like a good investment. I don't think this makes a difference though.
  • Once the connection was complete and running, I connected the Coaxial cable to the modem, then connected the modem via ethernet to the WRT54G's WAN input, and the PC to one of the ethernet ports of the WRT54G, then I powered up both the cable modem and the router. (The router must be set in DHCP mode).
  • After a bit of waiting, the router directly obtained a dynamic IP and all seemed well. Loading up any browser page in the computer redirected me to a comcast page which included a link to download the software that comes with the Comcast self-install kit. I don't even need to insert a CD!
  • Downloaded the software, then executed it. It turns out it's basically a specialized IE window, doing HTTPS requests to Comcast in the background. Here they actually activate routing for your cable modem, but at the same time they're assuming that the PC is connected directly to it, and so they seem to reconfigure the modem to talk to the PC's network card (which isn't connected directly to it). When the registration and configuration is done, they reboot the modem automatically, at which point nothing works.
  • Aha! The reboot seemed to be key.
  • So, I did a hard restart on both the cable modem and the router (first disconnected the router, then reset the modem, then reset the router, then reconnected the router) at which point the cable modem seemed to find the router agreeable once more.
  • And that's it!
From what I gather the modem does attach itself to one MAC address, but that is reset when it reboots, so spoofing the MAC address (which sounded like a weird requirement in the first place) doesn't appear to be an actual requirement. The MAC address of the cable modem itself is registered with Comcast, so you'll need to let them know if you get it replaced.

After all that, speeds are pretty great, 3 Mbps down, 768 Kbps up (or more), and it's working well so far, keyword here being so far since there were some signal strength issues that made installation more tedious than it should have been, and those gremlins have a way of showing up again...

PS: I also got HDTV with Dolby Digital. Not that many channels, but one word: Wow.

Categories: technology
Posted by diego on August 16 2005 at 11:47 PM

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