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I have a high speed internet via a cable modem. I received 2 ip addresses from my provider. Can I use 2 different routers: Linksys and Watchguard Firefox Soho, and still have dhcp enabled on both?

Well, you certainly can, but in most cases it only makes things more complicated than they need to be.

To actually do it, I'd put a hub in front of the two routers. So your cable modem would go into the hub, each router would be connected to the hub, and each would configured to respond to one of your two static IPs. You could then connect your computers to one router or the other, as you saw fit.

I'm just not sure why, in most cases, you'd want to do so.

The drawback here is that your machines on one router will not be able to share folders or printers with machines on the other router. Each router represents its own private sub-network on the internet.

Multiple internet IP addresses are really only useful if you have multiple computers that you want to access from the internet. For example you might want to set up two web servers, in which case each would need its own IP address. For most common home and small business situations, that kind of setup is actually pretty rare.

My ISP has allocated me 5 IP addresses here at home, but I use only one. All the computers in my house (8, I think) are connected behind a single router. I really don't have any need for the other 4 IP addresses at this time.

I suspect that, unless you're doing something special, you really only need one of your two IP addresses. It'll certainly be the simplest approach.

Article C2324 - April 6, 2005 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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32 Comments
Bob
April 8, 2005 8:36 AM

Some cable ISPs configure your cable modem with only 1 IP address by default and charge a few dollars a month for extra addresses. If your ISP only provides you 1 address, a router would be required to share that address between your computers.

Jordan
August 15, 2005 11:08 AM

A special case where you might WANT something like described in the article;

- you have a home network behind one router (using your first IP address)
- you have a server with your second IP address

So now, your server is now 'isolated' from your home network; which should make your home network more secure (since potential hackers won't be able to get to your 'home network' THROUGH your now isolated sever)

Another case might be if you want to seperate two groups of people (so that each group is 'isolated' from each other) ie. So Group A can't get onto Group B's network and visa versa.

panmsizcz
September 30, 2005 4:19 AM

What connecting one computers on two ip by one cable(wi-fi site)

panmiszcz
September 30, 2005 4:21 AM

i have ip, what i make detect how many computers working on this ip? hmmm?

Jason
October 13, 2005 11:20 AM

simple fix to get 2 ip's on 1 line, why couldn't i think of that...you're the man!

Amy
December 1, 2005 9:54 PM

Hello,
I am trying to set-up 2 ips in my house. My provider gives me 3 ip addresses, which right now I am only using one of course. My question is do I need a separate router (2) for each ip address? Right now I have a wireless route that connects two computers, xbox, 3 playstations. But I need to take advantage of at least one more of the ip addresses for a different computer (this computer is for a room-mate which needs a different ip address). So do I follow the same directions above by getting another router and hub?

Thanks, Amy

Alex
January 10, 2006 2:18 PM

Hi,
I need to do this, but im using two dynamic ip addresses, I was woundering if insted of using a hub, could you use a switch. I have a switch I am not useing. I want this to seperate my one xbox from the other because I get network errors with them on the same network. Thanks for any help!

Roger
February 15, 2006 6:30 AM

My router alows me 5 ip addresse and I nee 10. Howdo I make that happen.

Ross Musselman
March 9, 2006 9:40 PM

I have a high-speed line coming in to my home with DHCP for my initial wireless router (D-Link). DHCP is running on that router. Behind that, I would like to place another wireless router that would serve a separate section of the house (Netgear). I purchased a second router because it was cheaper than an access point. Did I make the wrong decision?

Michael
August 19, 2006 10:45 AM

on your comment, How can I use two ip addresses from one cable modem, i want to ask if i can use switch instead of hub.

Sean
September 14, 2006 7:00 PM

I own a duplex, both myself and my tenant are running able modems... other than purchasing a router with two WAN ports to do load balancing, is there a way to amalgate the connections to double my theoretical speed? For instance, and I could probably just spend an afternoon testing this, could I take oen of my spare switches, run both cable modems into it, and channel that into the WAN port of a single router, from there hit another switch, and allow our networks to merge? I can VLAN if I feel the need for security, but I really don't... During the week I use a lot of bandwidth on media applications while they use very little for email and the like... While I'm gone on weekend hikes they play WoW and other online games, so sharing the bandwidth would work out well...

Chris
November 10, 2006 9:12 AM

Can this also be done with a dsl modem? I know that with a dsl line you usually use PPoE to connect. Our dsl provider has given us 6 ip public ip addresses to use and due to having several servers running we would like to issue each of them a public ip.

Marshall Leitem
November 21, 2006 3:54 PM

The reason why someone would want to do this is to get 2 xbox's on xbox live at the same time in the same household.

Since there doesn't appear to be a way to get two of them to sign in at the same time on the same connection due to port issues.

ijlal
December 23, 2006 2:40 PM

Hello I have problem with my ISP I need Band Width 512kbps Static IP but he cant provide me. they can give me Band Width upto 64kbps Eight different Static IPs. I wanted to know is there any Software or Device from which i can get help to make by my self a Static IP of 512kbps. Please answer me in detail so i can understand

Leo Notenboom
December 23, 2006 3:11 PM

No. If they can only give you 64kbps then you can only get 64kbps no matter how many IPs you have.

Greg Thurmon
January 30, 2007 5:54 AM

Leo, I just read your comments on 'How can I use two ip addresses from one cable modem?' and I have a question. First the problem: two divisions in our company who were completely independent, seperate physical locations, domain controller, webservers... (except for VPN), are moving into our new building together. The long term goal is to have one domain and one network, but my short term goal is to get people back to work. I need to maintane two domain controllers each on a seperate subnet behind one cable modem with 5 static ip address assigned to it. Your solution of a hub sounds easy enough. Is that the best way to share the internet connection for now or is there a better way?
Thanks a lot for your advice.
Greg

steven
November 26, 2007 11:41 AM

can i change my modem smartax to a different router

Louis KIm
March 7, 2008 7:40 AM

Leo,

I have client software for car washes that require that I use multiple IP addresses, how do I setup my router to use a single cable modem with two separate IP addresses?

I'm using a netgear FVS318.

I alos have 2 connections for credit card processing, 1 for a computer, and 1 for my CCTV system.

Please help, COX is not help, and the company who makes my car wash equipment doesn't know how to port forward, so this is way beyond them!

Thanks

Lou

mugz
October 2, 2008 5:26 PM

i have a DSL connection and the ISP gave us 7IPs so how can i possibly use all of those IPs and i'm using D-Link router..

please help with these

Patricia Boston
November 5, 2008 4:43 PM

I put two computers on the same modem now i was wanting to information to the other so how ?

Nelzihno
November 6, 2008 5:45 AM

Hi,

I have one broadband line into my property, yet my ISP has allocated 5 IP's.

I want to set up SBS 2008 in a test environment to get to grips with it before rolling it out to a client. To test exchange i need use 2 external IP's but i only have one connection, and my router has only one WAN port.

Is it possible to configure a draytek 2600G to use 2 external IP's through one phyical connection?

There are various options such as WAN alias addresses, but i am unsure how to link the external IP's to the correct machine? Do i create VLAN's and set port forwarding?

Any help would be greatly recieved!!

John
December 12, 2008 6:46 AM

My cable provider does not supply static IP addresses. Can this still be done without static IP's? If so how does each router know to get a different IP address?

Tanel
February 17, 2009 12:03 PM

Hi, Leo
Can u help me with that, i have one router and 2 computers. they both are same ip-s. but i play one game with my brother and i was wondering, if there is possible to change ip-s to different? then we could have different ip-s with one router. can u help please. thanks

marcus ridley
February 19, 2009 8:17 AM

hello i need second 2 ip address beacuse i have ojo and viedo phone now they spreated easy to contact which can easy to contact ????

bridgetbutler
February 25, 2009 9:53 AM

i have a laptop that is connected to peoplepcdsl modem.my daughter who is in the same apartment as i am has a verizon dsl modem.how can we use our computers at the same time when i only have i phoneline

You can't - at least not the way you think. The DSL on your phone line is connected to only one, PeoplePC or Verizon, regardless of which modem you use.
- Leo
26-Feb-2009

Kenny
February 15, 2010 10:56 PM

Hey. I have a couple of questions.
Like let's say, I'm currently playing Xbox Live, and I have 1 cable modem and I'm using 1 wireless router.
When my family uses the computer I start lagging on Live. If I buy a second router, would it stop this problem?

Unlikely. You're more likely limited by the speed of the internet connection to your home.
Leo
16-Feb-2010

Steve
May 19, 2010 9:45 AM

I have 2 networks setup and 2 IP addresses. I use one network for general home stuff and my wireless IP cameras are on the other. This way, I don't eat up the bandwidth of my home network. I access my cameras through my dyndns domain via port forwarding on my camera network. So far this has worked for me very well. This is the only reason I would do this since it is a specialized use.

LARA
July 13, 2010 12:42 PM

INTERESTED IN IP CAMERA TO PUT AT LAKEHOUSE. WE DO NOT HAVE INTERNET THERE. OUR PRIMARY RESIDENCE IS ABOUT 50 MINUTES AWAY. 1 CAN AN IP CAMERA BE USED AT OUR LAKEHOUSE AND AND DO I GO ABOUT SETTING UP ?

CD
January 11, 2011 8:58 AM

Took me 2 days to figure out, thought I'd post it for others the easiest way to get two playstation's running simultaneously on a home network is to use a Switch and make sure your ISP provides you with 2 IP addresses. You'll NEED 3 IP addresses if you plan to use any other computers on the network. Use the router to separate the rest of the network from the two ps3. Use wired connections for the PS3.

Setup
MODEM
-SWITCH
--1 PS3
--2 PS3
--Router
---PC1
---PC2
---WIRELESS LAB TOP
---ETC...

This setup will guarantee your able to join parties together in seconds(no waiting time or party kicks)

You shouldn't ever be kicked out of game by connection errors. (typical problem with this game)

Which means you won't get penalized for the game's inability to support all routers properly.

(why don't games collaborate with a router company, like a certified PS3 Router)

Uncharted unlike most other games has serious problems finding players, joining parties, or disconnecting from games, after testing, configuring many routers, opening ports, static ips, dmz, firewalls, routing ips, qos engine priorities, etc. your just wasting your time! If your not experiencing problems, great! ignore this, but if you are, don't waste your time!, get the setup i mentioned above and you will be set gaming for 10 hours straight together with your brother or sister watching others get disconnected .

Spread the word! this is specifically for Uncharted 2, connect directly and you won't have a problem anymore. Hopefully Uncharted 3 will have fixed these network issues. Enjoy!

THANKS BIG TIME TO LEO FOR THIS ARTICLE THAT HELPED ME SOLVE THE PROBLEM :P

Lon
April 28, 2011 3:09 PM

I have 2 PC's and 2 IP addresses,each pc recognizes 1 IP address. I have it connected internet cable to modem,from modem to a linksys 5 port switch and from there a network cable to each pc works great. I did this because when I had 1 IP address and used a router my buddy and I would go to same online game play for a while but then get kicked, not sure if server saw us as one in the same. Anyway someone said if I got 2nd IP address and connected as above game server wouldn't kick us and it never has since. Each pc always has the same IP address they never switch back and forth.How does each pc recognize same IP address everytime you boot them ?

Brian
January 11, 2013 11:24 AM

You should change the title of this article to something like "Should I use two IP addresses from one cable modem."

This is the antithesis of a how-to article. Instead of explaining how to do it, it argues against doing it at all. I'm wonder if you even know the answer to the question in the first place.

johnpro2
April 11, 2013 3:30 PM

@ Brian
"This is the antithesis of a how-to article."
********
Much of Leo's advice seems to be pitched at the home user rather than the corporate sector/pure technical advice sector.
That advice appears to try to determine what the home user/writer is trying to achieve and he gives advice that he feels would be more appropriate to their needs.
Many replies appear to be not strictly from the "workshop manual "
Jp

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