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I am attempting to have two computers communicate within a network that has three routers with 3 different IP ranges.

We have an internet connection coming in at the main building, with the range of the main building being 192.168.0.xxx, and then the two secondary buildings have their own ranges, 192.168.1.xxx, and 192.168.2.xxx.

Each building currently has internet access, but does not see computers in the other ranges, or allow ping, or other access.

I am trying to allow the computers within the 192.168.1.xxx range to access the 192.168.0.xxx range, and vice versa. I am sure this is possible, but not sure how to get it up and working.

I have looked into static routes, but can't get them working. I have looked at "dual-homing" using the DNS of the computer to add in the second network, and couldn't get it to work either.

I have found another option of changing the subnet mask to a /16 to solve the problem, however I am not convinced that it will work either.

Does anyone have a suggestion to solve this problem?

                                             EG -> R -> 192.168.1.xxx
                                            / 
WWW -> M -> R(192.168.0.xxx) -> S -> EG -> <
                                            \ 
                                             EG -> R -> 192.168.2.xxx

M-Modem
R-Router
S-Switch
EG-Engenius Wireless Bridge, used to share network wireless between multiple buildings.
  • You mention that there are already 2 routers in the setup, if they are properly set up they should have one interface in their building's network and one in the 0 network. Is that the way they are set up? – fvu Aug 31 '15 at 14:31
  • Yes there is a router in each building, and they both have their own settings interface, is that what you are referring to? – Brett Adams Aug 31 '15 at 14:33
  • What kind of routers do you use in the secondary buildings? plain routers or router-firewall-nat device things like you normally use to connect to the internet? – fvu Aug 31 '15 at 14:36
  • plain routers, using Linksys WRT1900AC for all three routers – Brett Adams Aug 31 '15 at 14:40
  • This really should be a Super User post, I believe. – Hyppy Aug 31 '15 at 14:53
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The "routers" you are using are all-in-one wireless access points, NAT firewalls, and routers combined.

Turning off the Network Address Translation of the secondary routers may help, but you'll still need to introduce static routes on the primary one. Alternatively, just turn off the entire routing portion altogether on the secondary routers and configure them as access points. Boom, everyone is on 192.168.0.0/24.

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  • not sure you can even disable all that firewalling and NATting jazz on these consumer devices, so gluing the networks together as one flat /24 is indeed probably the least painful thing to do. – fvu Aug 31 '15 at 14:58
  • Ahh ok, I am looking into it, I will comment back my success or failure. @fvu I need the separate IP ranges if possible. I may be looking at different devices if those won't work. – Brett Adams Aug 31 '15 at 15:36
  • @BrettAdams in that case reducing the WRT's to simple access points and adding normal routers (one in each secondary building) would be the way to go. We've had good experiences with the low cost Ubiquiti ERLite (gigabit ports, highly configurable but cost per unit < 100$. Some study required, as most of their functionality should be configured via the command line) – fvu Aug 31 '15 at 15:51
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Your .1 and .2 networks are default routing via the .0 network, so they know how to reach the hosts in .0 by virtue of the default route.

Your problem is that the hosts in .0 default route towards "www" in your diagram -- they don't know how to reach the .1 and .2 networks, so return packets are sent to the default router and it has no idea where to send them, so it sends them out to the internet, which of course doesn't reach the networks in your other buildings!

The easiest solution is to add a static route to the "www" router for 192.168.1.0/24 and 192.168.2.0/24 via the relevant routers (using whatever their addresses on the .0 network is)

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