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Kadin · 08-02-2008, 06:01 PM

If I am understanding you correctly, you want to set it up so that you go from your cable modem, and then to a switch, and then to both your Vonage box and your WiFi router, and your PC, with each on a separate port of the switch. This would, in theory, give each device plugged into the switch (Vonage, Wifi router, PC) a separate internet-facing IP address.

The short answer is that yes, you can do this. However, if you are on a typical Comcast consumer-grade broadband plan, only the first device to turn on will be able to access the Internet.

Most consumer broadband plans only include the use of one internet-facing IP address. If you attach more than one device to the cable modem (via a hub or switch), they will not get IP addresses from the modem. Only either the first device to connect, or the device whose MAC address is registered with your ISP (which way it works depends on your ISP — Comcast is first-on, not sure about other ISPs), will get an address and be allowed to connect. This is why people connecting multiple computers to one broadband connection have routers that perform NAT, effectively "hiding" all the devices on the network behind one IP address. It sounds like you're trying to avoid having to have your PC and the Vonage box behind NAT … while that's understandable, it's going to cost money, because IPv4 addresses are in relatively short supply.

If you want more than one simultaneous internet-facing IP address, you have to call your ISP and pay for more. This isn't a very frequent request so be prepared to explain yourself, in very small words, several times as you work your way up the chain of command. What you probably want is multiple dynamic IP addresses; you could if you want buy a block of static IP addresses, but this will be expensive.

Comcast used to have a plan where they would sell you 5 or so simultaneous dynamic IPs for an extra $5 or $10 per month; it was variously called the "Home Networking" plan, or the "Gaming Pack" [see here]. I don't know if it's still offered — I've never had any luck in trying to order it.

I wanted to set things up similar to how you are asking about having them; I wanted to have the cable modem, then a switch, and then an SSH server, VoIP box, and router/gateway connected to the switch. This would require three simultaneous IP addresses. Eventually I gave up; I couldn't find a plan at Comcast that would let me do it that didn't cost a fortune (they kept wanting me to upgrade to a 'Business' plan). If you decide to try and go this route ... good luck.

Can't wait for IPv6 ... it'll be nice to not have to pay through the nose just to have globally routable addresses for every device in a LAN. That's how the Internet was supposed to work, back before NAT screwed it all up, anyway.

08-02-2008, 06:01 PM	#3 (permalink)
Kadin Upright Location: Virginia	If I am understanding you correctly, you want to set it up so that you go from your cable modem, and then to a switch, and then to both your Vonage box and your WiFi router, and your PC, with each on a separate port of the switch. This would, in theory, give each device plugged into the switch (Vonage, Wifi router, PC) a separate internet-facing IP address. The short answer is that yes, you can do this. However, if you are on a typical Comcast consumer-grade broadband plan, only the first device to turn on will be able to access the Internet. Most consumer broadband plans only include the use of one internet-facing IP address. If you attach more than one device to the cable modem (via a hub or switch), they will not get IP addresses from the modem. Only either the first device to connect, or the device whose MAC address is registered with your ISP (which way it works depends on your ISP — Comcast is first-on, not sure about other ISPs), will get an address and be allowed to connect. This is why people connecting multiple computers to one broadband connection have routers that perform NAT, effectively "hiding" all the devices on the network behind one IP address. It sounds like you're trying to avoid having to have your PC and the Vonage box behind NAT … while that's understandable, it's going to cost money, because IPv4 addresses are in relatively short supply. If you want more than one simultaneous internet-facing IP address, you have to call your ISP and pay for more. This isn't a very frequent request so be prepared to explain yourself, in very small words, several times as you work your way up the chain of command. What you probably want is multiple dynamic IP addresses; you could if you want buy a block of static IP addresses, but this will be expensive. Comcast used to have a plan where they would sell you 5 or so simultaneous dynamic IPs for an extra $5 or $10 per month; it was variously called the "Home Networking" plan, or the "Gaming Pack" [see here]. I don't know if it's still offered — I've never had any luck in trying to order it. I wanted to set things up similar to how you are asking about having them; I wanted to have the cable modem, then a switch, and then an SSH server, VoIP box, and router/gateway connected to the switch. This would require three simultaneous IP addresses. Eventually I gave up; I couldn't find a plan at Comcast that would let me do it that didn't cost a fortune (they kept wanting me to upgrade to a 'Business' plan). If you decide to try and go this route ... good luck. Can't wait for IPv6 ... it'll be nice to not have to pay through the nose just to have globally routable addresses for every device in a LAN. That's how the Internet was supposed to work, back before NAT screwed it all up, anyway.