Sharing Broadband Internet Access with Motorola SB4100 Cable Modem

[Stealth1024]

According to the directions this modem supports up to 32 users on a network. At first I assumed it had built in NAT and DHCP, however after careful reading it never says that. In fact, it talks about how each computer might need a seperate IP (well duhh) but how this might cost a "little" more per month.

Well thinking that this did perform NAT and act as a DHCP server, I had this modem plugged right into a 4 port hub, off of which is plugged two computers and a wireless access point in bridge mode, on the other side of which is a second wireless access point which completes the bridge plugged into an 8 port switch with 5 additional computers.

Even though this modem was plugged into this network the original computer it was configured on still had internet access so I didn't think anything of it not having NAT or DHCP support... Well I know realize that non of the other computers can gain access to the internet. Conclusion: either I need a configuration program or this is just a bland old cable modem (if it is then how did this work over the network???)

So my question is, since this one computer has access to the internet, but only has one network card, how do I share it over the network and have that computer perform NAT and DHCP? Is it as simple as enabling internet connection sharing? What if I want to move this to a dedicated server?

 

[marat]

The way it works is that Cox (or whatever cable company you have) authenticates you with computer name and your cable modem (physical address of cable modem to be precise). So, if you want to connect extra computer, you have to ask Cox give you another name and pay $4.95 per month per computer. What you should do is to put 2 network cards in one of the computers and turn ICS on it. One network card will connect to cable modem and another one to the hub. All other computers will use 1st computer as gateway. Here is a nice link for you Internet Connection Sharing.

 

[alanwj]

Unless I understand your setup wrong, I believe your system that is "sharing" the connection is going to have to have two IP addresses, one for the connection to the internet, and one for the local network. That means you are going to have to either set up IP aliasing on your existing network card (is this possible in Windows? I've never done or tried it), or you will need to put another network card in the machine. It sounds like, with the setup you already have, that sticking another $20 network card into the mix wouldn't break you.

 

[Stealth1024]

would this work to share if I simply put a second card in the sharing computer and connected everything to the hub/switch somewhere on the network? (cable modem plugged into hub just as it is now)