Simple(?) routing between two IP Ranges (subnets?)
June 1, 2024 6:40 AM Subscribe
Further to my question of a few days ago I've accepted I'm going to have to renumber.
But there's one device on the LAN providing a service I just can't renumber. The system just won't allow it be changed now, so the service is expected to exist at 192.168.2.5. All other devices on the LAN are on 192.168.0.x
Is there any way I can use a piece of network hardware, I am guessing a second router, to allow 192.168.0.x devices to find this 192.168.2.5 device? I'm guessing I would plug the second router into the first (is this double NAT?) and then setup a static route?? This might seem like basic networking to some but it's my first foray into this. All the networking I've done to date is basic stuff with all IPs being in the same (class C?) network. Now I'm for reasons out of my control needing to bridge two class c networks together....
HELP!
Thanks :-D
But there's one device on the LAN providing a service I just can't renumber. The system just won't allow it be changed now, so the service is expected to exist at 192.168.2.5. All other devices on the LAN are on 192.168.0.x
Is there any way I can use a piece of network hardware, I am guessing a second router, to allow 192.168.0.x devices to find this 192.168.2.5 device? I'm guessing I would plug the second router into the first (is this double NAT?) and then setup a static route?? This might seem like basic networking to some but it's my first foray into this. All the networking I've done to date is basic stuff with all IPs being in the same (class C?) network. Now I'm for reasons out of my control needing to bridge two class c networks together....
HELP!
Thanks :-D
would suck but might work - get a regular router (like you'd get for home), configure it to hand out IPs on the 192.168.2.x range, turn off its Wi-Fi support. plug your main network into its WAN port, and the device into one of its LAN ports. configure the router to forward any ports that the device is expecting to receive traffic on to the device. (some routers have a blanket forward that you can set up too that'll forward anything incoming to a specific device - this would work too.) then, on your main network's router, configure it to always hand a specific IP out to the router box so it's not moving about on the network randomly, and reboot the second router after you've done this. now you should be able to get to the 192.168.2.x system by using the second router's 192.168.0.x IP address. this does mean you have one more device on your network and you'll have to find a home router that ideally allows you to turn off its WiFi modems and you'll have to remember to plug into the second router's LAN side if you ever need to adjust it.
you can theoretically do this with routing and forwarding rules set on the main router too - lots of people do this to keep some semblance of separation between classes of devices on a single network - but how specifically depends on your main router, and if it's the one that Sky gave you it may not have controls for such things. (a quick Kagi search did not turn up a manual for the BR440 so I can't say for sure.)
posted by mrg at 8:17 AM on June 1
you can theoretically do this with routing and forwarding rules set on the main router too - lots of people do this to keep some semblance of separation between classes of devices on a single network - but how specifically depends on your main router, and if it's the one that Sky gave you it may not have controls for such things. (a quick Kagi search did not turn up a manual for the BR440 so I can't say for sure.)
posted by mrg at 8:17 AM on June 1
Response by poster: Thanks @mrg - I like your thinking and I did originally have something similar setup (double NAT with everything strung off the second router) but….
With your solution I don’t see how for example IP phones on the 19.168.0.x network would be able to “find” the VoIp server (because that’s what it is) at 192.168.2.5?
posted by dance at 11:25 AM on June 1
With your solution I don’t see how for example IP phones on the 19.168.0.x network would be able to “find” the VoIp server (because that’s what it is) at 192.168.2.5?
posted by dance at 11:25 AM on June 1
There's not really a good way to do what you're asking. Even if you define a route on your 192.168.0.0/24 network so that those devices can see the single device at 192.168.2.5/32, you'd also have to define a route from that device to the new LAN. Why can't you reconfigure that one device? Is it because it's inaccessible over the current network topology? How did it get the IP address it has? I'm going to imagine the scenario that it was configured with a static IP, and it is no longer accessible from the new LAN network because of missing routes.
In my imagined scenario I'd temporarily disconnect the VoIP server and a single computer from the physical LAN and connect them directly to each other with an ethernet cable*. I'd then configure the computer to use a static IP in the same subnet as is currently defined on the VoIP server (say, 192.168.2.4, network 192.168.2.0, and subnet mask 255.255.255.0). Then you can reach the VoIP server via its (old) IP address and reconfigure it to use a new static IP address**. Once you've updated the configuration the VoIP server will become inaccessible in your temporary network, so you'll need to switch your computer back to DHCP and restore the network cables how they were. Failing all that, look for a hard reset function for the VoIP server and start over fresh, since it will probably default to DHCP after such a reset.
* In the old days you might have needed a crossover cable for this, but I'm assuming that at least one of the devices will have an auto-sensing network port that will allow you to use a regular patch cable.
** Technically what I'd do is configure DHCP with static assignments, so if you ever have to go through this again the VoIP server will just get a new address from your new/reconfigured DHCP server and avoid the need for another manual configuration. I periodically export a backup of my router's configuration so I have all the MAC addresses and their assignments to make configuring a new router easier.
posted by fedward at 12:37 PM on June 1 [1 favorite]
In my imagined scenario I'd temporarily disconnect the VoIP server and a single computer from the physical LAN and connect them directly to each other with an ethernet cable*. I'd then configure the computer to use a static IP in the same subnet as is currently defined on the VoIP server (say, 192.168.2.4, network 192.168.2.0, and subnet mask 255.255.255.0). Then you can reach the VoIP server via its (old) IP address and reconfigure it to use a new static IP address**. Once you've updated the configuration the VoIP server will become inaccessible in your temporary network, so you'll need to switch your computer back to DHCP and restore the network cables how they were. Failing all that, look for a hard reset function for the VoIP server and start over fresh, since it will probably default to DHCP after such a reset.
* In the old days you might have needed a crossover cable for this, but I'm assuming that at least one of the devices will have an auto-sensing network port that will allow you to use a regular patch cable.
** Technically what I'd do is configure DHCP with static assignments, so if you ever have to go through this again the VoIP server will just get a new address from your new/reconfigured DHCP server and avoid the need for another manual configuration. I periodically export a backup of my router's configuration so I have all the MAC addresses and their assignments to make configuring a new router easier.
posted by fedward at 12:37 PM on June 1 [1 favorite]
OK maybe I'm missing something here, can't you just make all the netmasks 255.255.0.0? That's how I have my DHCP server configured, because I prefer 192.168.0.x but my Mikrotik comes up as 192.168.88.1.
posted by wrm at 1:10 AM on June 3
posted by wrm at 1:10 AM on June 3
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posted by Klipspringer at 7:37 AM on June 1 [1 favorite]