Comcast Cable Modem install?

[Dustin Decker]

On Tue, 17 Dec 2002, Gene Dascher wrote:

> What do you mean "only connect the cable modem to the firewall or you will
> have to work around that"?  What else would you connect the firewall to?
> The only MAC address authentication that they do is on the Cable modem
> itself, at least so far that I am aware.  I am using an old 486 as my
> firewall with an old ISA NIC.  The PCI NIC that they gave me is on another
> machine.

This is an issue with both Comcast _and_ RoadRunner.  Nearly all cable
providers configure their head-end (for you dsl folks, think "dslam")
to recognize a specific number of MAC addresses connected to the cable 
modem.  If you cable directly from a pc to the cable modem, then they see 
one MAC.  If you cable the modem to a hub or switch, and then plug in 
multiple computers, then they see multiple MAC addresses.

This in and of itself is no biggy really - until you're ready to request 
an address from the DHCP server.  They generally configure to allow only 
one MAC address at a time to grab an IP.  Although you can turn off or 
disconnect the pc that last leased one, the MAC address is still cached on 
the cable modem.  The easiest way to clear it is to powercycle the modem.

I have found that RoadRunner is quite easy to deal with on this - I just 
gave 'em a call and asked that they open mine up to allow multiple MAC 
addresses... for my home PC, the wife, and that laptop I wander back and 
forth between work and home with.  (Whatever story you need to tell them 
to get however many IPs up and running.)

Hope this helps - Dustin

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