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I'm not super keen on the fancy networking terminology to describe my situation, so please help me out with that as I describe my problem in the best terms I can.

Currently, we have a network living on the 10.0.0.0/24 subnet. We just purchased an embedded device that, apparently, has its IP flashed onto it by the manufacturer ( or at least that's how the tech who installed it described it ), and its IP address is 192.168.1.200.

While I'm fully confident there's a semi-nice way to change the IP on this embedded device so that it can live on the same network as our other computers, is there a way I can just get the router to route traffic to this device and achieve the same goal? Currently the network and device are literally on the other side of the planet from me, so performing as few steps possible to get this working would be great.

If this matters, I have a SW24 router from SYSWAN.

Thanks!

UPDATE: I should probably mention an additional constraint: I can't change the IP address of the router so that it lives on the 192.168.1.0/24 network. Or at least, I don't think I can, previously it has caused problems. The two modems both all ready have the IP address of 192.168.1.1, and the SW24 is Load Balancing our Internet between them. Previously when I've tried to give the router an address of 192.168.1.254, it seemed to cause problems with our Internet.

Clarification: With regard to how the router should handle the traffic: I want the 192.168.1.200 host to work as though it were just another device on the 10.0.0.0/24 network. That is, from my 10.0.0.100 device, I should be able to ping 192.168.1.200 successfully, and vice versa.

Update: Here's a picture of how the network is sort-of laid out right now. The two clouds are the two modems, the 10.0.0.1 is the SYSWAN router's private IP address. I'd like for both of the 10.0.0.100 and 10.0.0.101 devices (actually there are a few more on the network, as well, but this is for simplicity of the picture) to be able to communicate with the 192.168.1.200 device. It seems like this is a job for static routes, but that's where I get confused. What kind of static route do I need to add to my router?

lolnetwork

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I marked the selected answer as I did since it made the most sense, technically. For my particular situation, however, adding an additional device was an impossible feat, and it turned out only one device was required to interact with the 192.168.1.200 node, so adding another ip-address to that one node to sit on the 192.168.1.0/24 network was simplest and cost efficient. If the requirements change, I'll definitely implement Catherine's solution. –  mrduclaw Dec 30 '09 at 5:15
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2 Answers

up vote 2 down vote accepted

One possible (slightly messy) solution. Put the device on it's own network segment behind a router. Put the WAN side of that router on your 10.0.0.0/24 let's say it gets IP 10.0.0.254 for concreteness but it could be anything. Make the LAN side of that router be 192.168.1.192/26 (which will minimize it's overlap with your load balancer and maybe solve some of your other problems). Now put a static route on your 10.0.0.0/24 device to route 192.168.1.200 or 192.168.1.192/26 (which will allow you to put more devices on your new network, but may cause other problems) to 10.0.0.254. That should do it.

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I'm not sure I completely followed what you're saying. Put which device on its own network segment behind the router? Can't I just add a static route in the router for the 10.0.0.0/24 to the 192.168.1.200 device? –  mrduclaw Dec 20 '09 at 11:47
    
The 192.168.1.200 device cannot sit on the 10.0.0.0/24 network. In order to have a device that is on a different subnet, it needs to have a router. So you need to add a router between the 192.168.200 device and your 10.0.0.0/24 network. Then set a route to that device through that router. Your diagram above will never work because you have a device with an IP address that is not on the same logical network as the physical network it is connected to. –  Catherine MacInnes Dec 21 '09 at 2:31
    
OK, just to clarify: so you're saying I need to add an additional router to the picture between my current one and the 192.168.1.200 box, right? And then set the static route though this new router? That makes more sense to me, thanks. –  mrduclaw Dec 21 '09 at 13:20
    
Yep. That's what I'm saying. –  Catherine MacInnes Dec 28 '09 at 16:32
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Follow SW24 Technical Manual and it will just allow you to change the IP address of the SW24... problem solved.

Section 2.1 is specifically what you are interested in, and it clearly shows that you can have an address 10.X.X.X

After looking at your diagram, things get more interesting, and now it all makes a little more sense. You cannot have both subnets 192.168.X.X on both sides of the router, as this is an invalid configuration, what you need to do is either break down the from 192.168.1.1 interface into a much smaller subnet (say 255.255.255.252) and have the 192.168.1.200 broken down into a smaller subnet as well.

Configure your router with a IP address of 192.168.1.2/255.255.255.252 on the outside pointing to your load balancers, and both 10.X.X.X/255.255.255.0 and 192.168.1.201/255.255.255.252 on the inside with your default route pointing to 192.168.1.1 for its external routing.

This will allow any of your 10.X.X.X machines to talk to the 192.168.1.200 device via the router, and allow the 192.168.1.200 device to get out to the internet via the default routes on your router.

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Thanks for the response. Updated question accordingly. –  mrduclaw Dec 20 '09 at 10:43
    
Then setup another interface on your current router with a subnet of 192.168.1.100/255.255.255.0 and tell your current routers to setup a default route (0.0.0.0/0) to 192.168.1.200. You have to be very careful with terminology used or draw a simple diagram to explain in pictures what you need to have happen to the IP packets. –  Stephen Thompson Dec 20 '09 at 10:48
    
Yes, this looks more like what I'm expecting to see. But how do I go about adding another interface on my router? –  mrduclaw Dec 20 '09 at 10:55
    
With regard to the IP packets: I want the 192.168.1.200 host to work as though it were just another device on the 10.0.0.0/24 network. That is, from my 10.0.0.100 device, I should be able to ping 192.168.1.200, and vice versa. –  mrduclaw Dec 20 '09 at 10:58
    
Depends on the router model. I would just setup another IP address (192.168.1.100) on the same physical ethernet port so packets coming in on (10.0.0.0/24) go into the router, and back out the same physical interface, with your router becoming nothing more than a "router on a stick" –  Stephen Thompson Dec 20 '09 at 11:36
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