Multiple Gateways on one subnet

Hello Experts,

I have a customer that has two buildings connected with Wi-Fi and one subnet 192.168.0.x.  Building A has the WAN circuit and Building B has to go over the Wi-Fi to get internet. They want to put a new WAN circuit into Building B and add another FortiGate to go out to the internet but still maintain the Wi-Fi LAN. Can I do this without having to re-subtnet  Building B? Can I deploy multiple Gateways without creating any problems?
penntechsAsked:
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StampelCommented:
Sure, if you put the fortigate in the same 192.168.0 LAN , you just have to change the main gateway of building B equipments only. Then you will add the old WiFi persistent route with a lower priority (metric). Lower metric get higher prio :)
Check http://support.microsoft.com/kb/299540

route add 0.0.0.0 MASK 0.0.0.0 192.168.0.254 metric 10

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penntechsAuthor Commented:
The persistent WiFi connection is a site to site connection with the sole purpose of extending the LAN backbone. I don't think I can break that connection easily.
StampelCommented:
You do not need to break it.
Just add the new fortigate and the corresponding IP as default gateway for your equipments in Buiulding B.
Or do i miss something ?
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Qlemo"Batchelor", Developer and EE Topic AdvisorCommented:
If you configure your devices with static IP instead of DHCP, then yes, changing the default gateway on all devices in B is all you have to do. Nothing else.

If you use DHCP - ouch. You can trick the routing table to override the DHCP default gateway somehow by setting more specific routes, that is:
  route -p add 0.0.0.0 mask 128.0.0.0 192.168.0.x
  route -p add 128.0.0.0 mask 128.0.0.0 192.168.0.x

That way the default gateway remains in building A, but Internet traffic is routed to 192.168.0.x.
penntechsAuthor Commented:
Ok I will try it
penntechsAuthor Commented:
That worked thanks
Qlemo"Batchelor", Developer and EE Topic AdvisorCommented:
The "creative" part lies more in http:#a40402468 then in http:#a40402301, so I would have expected to get more points :(
penntechsAuthor Commented:
Sorry Olemo...I didn't change the routing table
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