Trying to link two networks?

We have two phone lines into our house, one business, one personal. They will both have separate broadband next week. Each has a OpenWrt flashed TP-Link Archer A7 router. My intention is to spread the broadband load between the two routers by having two networks. The idea being that when daughter streams a film the business is unaffected on the other network. As we have two phone lines and, in the UK, it is pretty much as cheap to have broadband/call plan/line rental as it is just a call plan line rental it seems a no brainer to have two broadband packages. It also gives us a small amount of backup.

Now the question is how do I link the two networks so devices on one can see devices on the other but each network only uses its own internet access. For instance, daughter can print a document on business printer. I can transfer daughter a file from the business network.

I was thinking of having one router use one subnet and the other use another subnet but am unclear how I get each router to link the two together. The routers are next two each other so cable link is easy but not sure of the router configuration I need.

I am thinking some sort of VLAN configuration on each router is probably the answer but am not sure what I need to do for configuration. Ideally using the LuCI gui.

Any help gratefully accepted, thanks.

CJ

On one of the routers (I will call it router 1) you will need to VLAN an Ethernet port so it can be connected to the LAN of the other router (router 2).

The two router's LANs need to have separate subnets, for example 192.168.1.0/24 and 192.168.2.0/24.

Router 1's interconnect port has a separate network (I will name it intercon), which holds an IP on router 2's LAN (192.168.2.2).

Since you're going to trust everything on both LANs you can put intercon into the lan firewall zone. More sophisticated firewalling is of course possible.

Since router 1 is now fully aware of the 192.168.2.0 network via the setup of the intercon interface, it doesn't need any additional static routes. A request to a 192.168.2.X IP will be routed to the interconnect cable and handled by network 2.

However router 2 is as yet unaware of the 192.168.1.0 network, so for 2->1 traffic (which includes the reply packets of 1->2 traffic) to be handled properly, this static route needs to be installed on router 2:
192.168.1.0/24 via 192.168.2.2

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That sounds excellent, thanks. I will endeavour to set this up with the two routers tomorrow as I am only waiting for the second Internet connection to go live at the beginning of next week but I should be able to test this setup now. I will probably come back with questions as I start using OpenWRT via the gui.

Many thanks
CJ

On Router 1 the VLAN3 setup - LAN4 will be set to Intercon and 198.168.2.2

At the moment this does not seem to work but I am wondering if LAN4 = physical LAN socket 4 on the back of the Archer. Will check that.

Please advise if my configuration seems correct, thanks.

CJ

On Router 1 the Intercon interface

The setup of the Intercon interface

Static Routing on Router 2 (which is subnet 192.168.2.X)

You can unplug the cable and see the port status change.

Bad network mask, change it to /24. Also assign the interface to lan firewall zone.

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Ok so IPV4 netmask set to 255.255.255.0 ? Not sure how /24 is specified.

Yes, /24 is 255.255.255.0. But it must match the netmask of the interface of the peer router.

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OK so I now have the interface assigned to the LAN firewall zone:

I also have the netmask applied to Intercon:

And? Is it working?

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Thanks - definitely a step forward. Well I can now ping devices in the other network both ways so that sounds pretty promising. However, if I connect my laptop to the other network (not the one it normally uses) then it connects to the network fine but it does not see automatically the printers or computers on the other network. Is it that Windows network discovery cannot see through the routing system? Is there anything I can do about this?

Thanks
Richard

That's right. windows network discovery uses multicast or broadcast packets (I think multicast). There was a lot of hassle we did to set up something like that across subnets on one thread a few years ago. it turned out even if we got the packets routed correctly windows refused to accept them because they weren't from the same subnet. (I found the thread )

Easiest thing was to simply create a printer and mapped drive using the ip addresses or names directly.

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Great, that is what I had hoped - I did think that I might have messed something up as this is my first exposure to Vlans so was not sure if I had done it correctly.

I did try adding a printer using an IP address and it detected the printer and then was asking for drivers etc so I stopped the process as I did not want to mess the existing settings on my Laptop. Also I need to wait a week before the broadband access will be enabled on the second network so am happy just to do proof of concept at the moment and will set the whole setup live in a weeks time.

Thanks to all that have helped.

CJ