Home Networking with Comcast

Junk the hub and get a router/switch. Problem solved and you'll only need a single IP address.

Otherwise if you are in a situation where you have rented 2 IP addresses from your ISP and they've given you ones in different networks (which looks like it may be the case) you'll have to add a 2nd NIC to each PC and set up a DCC connection between them with a crossover cable. Cost you darn near as much as a router/switch and not be nearly as good in some ways.

On 2nd thought, keep the hub in case you want to really expand but get a 4 port router/switch anyway.

 

These may be crazy thoughts, but I'd be interested in seeing if you can make any headway.

First, what type of Cable Modem are you using? Some of the Motorola Surfboards like the SB4200 can act like a DHCP server for 32 addresses when not connected to the Internet.

To check some of this out if you have one of the surfboards that seem to be somewhat common for Comcast, try using your browser to open http://192.168.100.1. This might open up the built in HTML for the modem. This has been true for the ones I have worked on.

If any of this seems to play out for you and you only have two machines, maybe you could assign static addresses to your two PC's. Maybe first try: 192.168.100.4 and 192.168.100.5. Use a moderate subnet of 255.255.255.0. If this causes errors try addresses outside the 32 that the modem can assign: maybe 192.168.100.45 and 192.168.100.46. Leave the subnet the same to make sure that you can access 192.168.100.1. and the other computer on the network. You can throttle the subnet back after you find a working solution if you are concerned about access to all the 192.168.100.xxx addresses.

Another possibility if you have a Comcast modem that has a USB connection. (I found the USB connection to be less effective than ethernet.) You could connect the Comcast modem to one of the machines via USB and try ICS for the network through the hub.

You could also use another protocol to establish connectivity between your PCs. Maybe something simple like NetBEUI? With 2 machines, congestion shouldn't be a problem. What kind of connectivity do you need between the two machines?

Honestly though, these ideas are nearly academic and for entertainment! Newt's suggestion is the best, the easiest, the simplest and the fastest way through the issue. The switch gives you dedicated bandwidth for each machine, allows them to work together, gives you a hardware firewall, network address translation, etc.. I've seen a new Siemens SpeedStream 2602 2port DSL/Cable Gateway/Router 10/100 with Built-in Firewall for $17 including shipping.

Except for the fun of it, can you justify putting the time into the more academic solutions? Anxious to hear what you decide and what things you try and how they turn out!

Thanks in advance for reading my musings! Hope there is some helpful information here.

 

NO.

The Router is a DHCP server. It will auto asign an IP to each NIC.

Plus the Router is a hardware Firewall. And also separates the LAN from the Internet.

And no need for ICS in XP.

BillyBob

 

Does that mean that they would not be DHCP server when connected to the Internet ?

If so then the Router would be the better choice I think.

BillyBob

 

I think this is a good question, if I can find a hub, I thought I might experiment. I'll post my results if I can get to it. I can open HTML pages on my cable modem at 192.168.100.1 when it is connected to Comcast. Based upon Steven R Jones' IP information the modem must somehow pass some DHCP functions to the Comcast DHCP server when the cable is connected but it still must be providing some network address translation for the LAN?

Clearly these cable modems are sophisticated interfaces. I wonder if they are really modems. Do we just call them that for convenience? There doesn't seem to be any audio modulation and demodulation of data as in the modems we grew up with. I refrain from calling a cable interface a router or gateway because it just gets so confusing. It seems like the cable modem that Steven R. Jones has is doing the work of a router and a gateway at least on the wide area network side of things.

Question for Steven R. Jones? Do you have fixed IP addresses from Comcast or is Comcast dynamically assigning them? My IP is dynamically assigned by Comcast. I didn't have to turn off DHCP support on my computers and specify individual IP addresses when I put them on the network.

Stephen, another crazy thought: Directory Name Services Servers(DNS) and DHCP servers are dynamically assigned for the benefit of Comcast and to provide redundancy. It seems like you can specify the same DNS for both your machines. Maybe there is a way to direct both machines to request DHCP services from the same DHCP server? This might get your IPs close enough so you could set your subnet mask wide enough to allow them to see one another. Ofcourse you might be out of business if that DHCP server went down.

A router/gateway still seems like the easiest. Good Luck! Mike

 

When I connect a new machine to the Router is it assigned an address immediately whether the Modem in acutally on-line or not.

But once thing I do not see about the SURFboard and would be of concern to me is that it may not have the hardware firewall that a Router does.

At least with the Router if my Software Firewall goes flucky I still have at least some incoming protection.

BillyBob