# Two Networks, One Internet Connection.



## local (Jul 20, 2011)

Hi,

I have a problem which I'm not entirely sure has a solution.

Currently i have two networks that are running from different routers, both share the same 192.168.1.0/255.255.255.0 credentials.
There is only one phone line into the building but both networks need access to the internet.

Is there any hardware i could aquire that would allow me to keep both networks on the same IP range but allow both to connect to the internet?
So in essense keeping both ignorant of eachother as to avoid IP conflics.

I myself am doubtful but I thought I would pop the question before pursuing the installation a second phone-line.


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## Phou (May 26, 2011)

What are your current network equipments? 

If you are using home routers you can probably add another one. 3 total routers.

1 router connects to modem, then the other two just connect to it on the LAN ports.

Though I wouldn't recommend having so many NAT devices it's still an ideal solution for SOHO network if budget is a concern.


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## Wand3r3r (Sep 17, 2010)

"Currently i have two networks that are running from different routers, both share the same 192.168.1.0/255.255.255.0 credentials.
There is only one phone line into the building but both networks need access to the internet."

Unfortunately this doesn't tell us much. You say two routers so I have to assume two internet connections but then you say one phone line.

One network have internet now and the other doesn't?
Do these two networks have a physical connection between the two?
How many devices on each network?


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## local (Jul 20, 2011)

Sorry for the lack of detail, I was trying to keep the question as readable as possible. 

The two networks are seperate, no connection between them. 

Each network has a router set up to dial the ADSL connection but only one has the phone line plugged in at any one time. Both use the same ISP login details. 

There is 6 devices on the first network and about 25 on the second. Merging the two networks is not an option due to complicated reasons. A second phone line is the obvious option but that comes at a £5000 cost which makes it the last resort. 

Hardware: One router is a Bintec R230a, the other a BT Business Hub. Purchassing any new hardware isn't a problem if it will resolve the issue.


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## Wand3r3r (Sep 17, 2010)

So your question isn't about joining two networks but one of having them share the same internet connection.


solution is simple given the criteria. put in a telephone line splitter and schedule when you dial out of each router so there isn't a conflict.

Now if you had connectivity between the two that would be different story.
You would use only one router
You would put in a vlan capable switch between the router and pcs
You could create two vlans, one for 6 and one for 24. This gives you the separation you desire while both could be on the internet and use the same ip range


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## joseerj (Jul 22, 2011)

I have the same kind of two networks here, and solved the problem like Phou said, one more cheap router bettwen modem and the two other routers.

Looking for answers to other problems, i've joined this forum only to say this. haha


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## Wand3r3r (Sep 17, 2010)

But that joins the two networks which doesn't fit the criteria "Merging the two networks is not an option"


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## Phou (May 26, 2011)

Wand3r3r said:


> But that joins the two networks which doesn't fit the criteria "Merging the two networks is not an option"


If merging the networks is not an option due to the subnet, I think the users would be ok if the WAN port of the router is connected to the LAN port of the router that is connected to the modem. In theory this should create 3 broadcast domain.


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## Wand3r3r (Sep 17, 2010)

not joining the networks is a political issue not a technical one. Seen it many times hence the suggestion to use vlans.


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## b7bu (Jul 23, 2011)

there are many solution for ur issue 

you can purchase new good router " cisco " for example or any router support Vlans and DSL connectivity 

link both networks by cable from each network switch to the new router 

and join each port to different Vlan and set the default gateway and DNS to the router ip in both networks , internet will work for both and you will keep them separate logically 

another way 

bring new PC .. any pc with good ram .. link it to the DSL router ... set 3 network cards on it .. 1st link to internet 2nd to lan1 3d to lan 2 

configure ur pc with windows 2003 is a router or setup ISA SERVER 

and dont forget to set different subnet mask for each network :wink:


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## local (Jul 20, 2011)

Thanks for the great answers, the VLAN is exactly what I had in mind.

And yes, the problem with the merging of the networks is political so the above solution will be fine.


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## Wand3r3r (Sep 17, 2010)

If the criteria remains the same of;
two internet connections
no connection between the two lan networks
then what needs to happen is....

What you need is a managed switch which is vlan capable. Both routers and all pcs are connected to the switch. You make vlan1 which contains router1 and 6 pcs. You create vlan2 with router2 and put all the 24 pcs on this vlan.

My proposal in post #5 was to save you the cost of one internet connection. You can do this using both internet connections. Only piece of equipment you need is the managed vlan switch.


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