Cable modem IP

Can a single cable modem provide multiple IP's if its conected to a hub? I assume so.
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If it's a cable modem and not a router, then it's not providing the IP at all, but your ISP is. (At least I don't know of a cable modem that provides IPs.)
RohnishIT EngineerCommented:
Get yourself a cable router (usually comes with 4 RJ45 ports)
This would solve your problem.
CDCOPAuthor Commented:
I did not make myself clear...was in a hurry...

I have my cable modem plugged into a hub. The hub feeds a router. Router gets ISP IP router then gives private network IP's etc. I want to plug a computer into the hub directly and get another IP from my ISP. This should work, but it does not. Could it be the cable modem? I have purchased another IP from my ISP.
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Here is a router made by Linksys that would do the job perfectly.
Hope it helps.
Sorry alittle slow on my last comment.
Call up your cable company and get them to check to make sure both IPs are pingable. Another thing you could do is to find out what the secondary IP is and configure that address as a static address on your system, then disconnect your router and see if it works.
Also when you plug in your system into the hub is it finding any addresses (possible from your router)? Can you ping any other systems?  What kind of hub are you using? When you plug in your system into the hub does the port light up?
Lee W, MVPTechnology and Business Process AdvisorCommented:
Most cable companies charge for additional IPs.  Time Warner (Road Runner) cable will provide additional IPs at $5 each.  Cablevision (Long Island, areas of New Jersey & Connecticut) will only provide 1 IP per cable modem.  Can they TECHNICALLY provide more, sure.  But nothing is free - especially from a cable company.
The answer is no.  You are not in a position to route and assign addresses for the internet.  You can only get addresses designated by a provider, you cannot increase them or make up your own, not of internet addresses, sorry, the provider is the one carrying the legal range of addresses, and btw, you cannot scope out of that to other subnets either.

I agree with leew comment. lpse2000 too.
IPs cost where connected. And you are not located at the top level, or at backbone, you cannot fudge either
CM --> (uplink) HUB --> router --> pc 1
                         |___> pc2
                         |___> pc3

Is this how you currently have your network setup? Make sure the CM (cable modem) is connected to the uplink of the hub for all the PCs to see the CM's DHCP server. Assuming you have purchased 2 IPs from your ISP one should go to the router and another one will go to either pc2 or pc3 depends upon which one is detected by the CM first. Both PCs' MAC of the NIC will be added to the CM's DHCP and if you purchased 2 IPs it will only add two computers there. If you have already connected everything like above, the CM will remembers two of the MAC of either ROUTER, PC2 or PC3 but not all 3. If you take one offline then the MAC of the offlined PC will still remembered in the CM so unless you reset the CM WHILE it's DISCONNECTED from the hub then it should reset the MAC list.

Let me hear what you think.
If I understand correctly, your physical configuration follows sysbot's diagram.  

Try the following:
1. Verify link status from the PC to the Hub.  
2. Verify the duplex and speed settings to make sure its not hard-coded on the PC
3. Verify your PC is configured to obtain an IP Address from a DHCP server
4. If this is a Windows platform use the ipconfig /release and ipconfig/renew commands to force DHCP communications.
5. If this is a Unix platform use the ifconfig command to evaluate and reset network configurations.

Other options:
1. What kind of router? How many ethernet interfaces does your router have?  If you have a second ethernet interface use it to see if you can receive the other ISP IP Address.
2. What type of CM do you have? Does it support port 80 access to it to view the configuration? If so try this to see what your setup is.
3. If you unplug the router does the PC receive either ISP IP Address.  If not check with your cable provider to see if they are using specific mac-addressess to issue the IP Address to and have them add your PC mac-address.
4. If all else fails configure your router to be a dhcp server and see if the laptop receives an IP Address this way.  This test will validate the IP stack on the laptop.

Please let me know your thoughts!
CDCOPAuthor Commented:
Nevermind. Problem solved. You do have to have a seperate cable modem. Borrowed a friends and it worked like a charm.
Mutiple CM is a non-technically way of solving it. It's like two difference houses each with their own IP.
CDCOPAuthor Commented:
And you have another way? I had it setup like you had above, but it did not work. I believe I have to have it setup with two, else the other would have worked.
CDCOPAuthor Commented:
Besides...I get more BW this way ;)
CDCOP > Problem solved. You do have to have a seperate cable modem.

I have a cable modem that provides 3 public IPs for my network.

It depands on the ISP infrastructure. I believe the most widespread is the MPLS router on the ISP side.

So this is their problem but it should work like this:

1. Connect the cable modem to the switch/hub - no need for "uplink" connection as stated in the comment above - in case u'll use it you won't get a link at all.

2. Connect all PCs to the hub.

3. Configure all PCs to work as DHCP clients.

You shoud call the ISP and require the solution of this problem.
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