Multiple LANs

Hi,

I have a tricky problem.

We have a LAN at work, with a few Pcs, a server, and wifi, and an ADSL internet connection
There are 2 other offices which also have the above.
We want to link the three buildings into one big LAN, using Mikrotik line of sight 5Ghz Radios.
Both of the other offices have line of sight to the main office, but not to each other.
They are situated in such a way, that a single 90 degree radio at the main office will be adequate to see both of the other offices.
All of the offices want to be able to keep their own ADSL connection, and be able to dhcp on their own LANs, as well as being able to see devices on the other LANs.
It doesn’t matter if all three LANs have separate dhcp, or if there is a single dhcp as long as the devices on each LAN uses only its gateway/ADSL connection, although it would be better if each LAN has its own subnet.
I have found out how to do it for 2 LANs using static routes, but nothing for 3 or more.
I expect that we will have to spend some money on hardware, I’m just not sure which hardware.
Any help would be gratefully received.

The setup is fairly easy - assuming that it’s possible to add static routes on the existing office routers.
I’ve attached a simple network diagram.

The wifi AP can be a SXT SA5, the wifi stations SXT Lite 5.
branch-offices.png

Hi jacekes,

Thanks for your reply. We have set it up with the figures that you suggested, although at the moment we only have 2 radios, the third is on its way.
we were having problems pinging certain windows machines from the other subnet, but we fixed this by turning off firewall in the non responsive pc.

Thanks again.

Simon.

Hello Again, I have a follow up question.

If I want to route traffic from one subnet through the internet of another, is it possible?
I have been trying to change the network adapter settings on the device, but it has been pointed out to me that maybe I should be using more static routes.

To make this more complicated, in the head office, we have another gateway, which has dhcp turned off. we have put this gateway at 192.168.10.3. We use this 3g gateway if and when we lose adsl, hence the need to be able to access it from the 11.x and the 12.x LANs.

Simon.

Make yr network easier not complicated.

Why not use site to site VPN since each of yr offices are connected to the internet?

DSL internet connections are in use, probably with very little upload bandwidth, so the VPN connections would be very slow. Connecting the offices via radio gives significantly more bandwidth.
Moreover, the DSLs are probably also unreliable.