Sub-nets - How to divide a small wired home network into 2 subnets?

Hi guys,

I have a fairly typical small wired home network, consisting of a handful of Win7 DHCP clients and a few shared fixed-IP public resources (printer, web-enabled DVR, intranet web and file servers etc), connected to an ADSL router (LiveBox) for Internet access which is configured with DHCP server for the clients and port-forwarding for some of the shared resources.

This has all been working fine for me and the missus, but now that we've just unexpectedly received some tenants who also require Internet access, I wish to get them isolated from our public resources as quick as I can, and have just ordered a couple of cheapo wired routers (BELKIN F5D5231) so I can try to set up 2 different sub-nets.

The intention is to have the ADSL router output connected to the inputs of both the 2 wired routers only, and for the new routers to provide 2 separated subnets, one for us with our shared public resources, and one for the tenants which I can independently manage for bandwidth throttling etc.

Hopefully I should be able to sort out the multiple gateway and DHCP side of things, but I know I'm way out of my depth regarding the sub-net division addressing and masks etc, so has anybody been down a similar road already who can offer me any advice please?

Electroguard said:

Hi guys,

I have a fairly typical small wired home network, consisting of a handful of Win7 DHCP clients and a few shared fixed-IP public resources (printer, web-enabled DVR, intranet web and file servers etc), connected to an ADSL router (LiveBox) for Internet access which is configured with DHCP server for the clients and port-forwarding for some of the shared resources.

This has all been working fine for me and the missus, but now that we've just unexpectedly received some tenants who also require Internet access, I wish to get them isolated from our public resources as quick as I can, and have just ordered a couple of cheapo wired routers (BELKIN F5D5231) so I can try to set up 2 different sub-nets.

The intention is to have the ADSL router output connected to the inputs of both the 2 wired routers only, and for the new routers to provide 2 separated subnets, one for us with our shared public resources, and one for the tenants which I can independently manage for bandwidth throttling etc.

Hopefully I should be able to sort out the multiple gateway and DHCP side of things, but I know I'm way out of my depth regarding the sub-net division addressing and masks etc, so has anybody been down a similar road already who can offer me any advice please?

The gateway IP's would all need to be different, one gateway for each subnet. The Belkin routers by default will have the gateways at > 192.168.2.1 so you can most likely leave one of those default and change the other to something like 192.168.3.1. Where the first router most likely is using 192.168.0.1 or 1.1. Notice how changing the third octet creates a new subnet.

Just leave DCHP enabled for each router, on the second router you will need to change the DHCP range to fit into the proper subnet so you can leave the first router and one of the Belkin router's at default, then on the third router change the DHCP range to use .3 as the third octet so the new range might be set as 192.168.3.2 to 192.168.3.255 which would give you 254 usable IP's. Then just plug the routers into each others LAN ports, LAN to LAN.

Thanks for your speedy reply Chev65. It'll probably be a week before I receive the routers from overseas and therefore able to plug things together, but at least that gives me time to get my head organised about how to set things up.
What you said about "Then just plug the routers into each others LAN ports, LAN to LAN" was unexpected and leaves me more confused than before I'm afraid, because it would appear to provide subnet nodes from both routers access to each other, so If I better explain what I assumed would be involved, perhaps you can clarify where I'd be going wrong.

If I call the original Livebox ADSL router 'A', it is currently configured as 192.168.1.1 with subnet mask 255.255.255.0 (making it class C I think, with 255 nodes). It has a couple of usable RJ45 ouputs, but I've only been using one of them to connect to a hub which is then distributed to my existing personal network nodes.

I had wrongly assumed that I'd need to insert one of the ordered Belkin routers (lets call it 'B') between existing ADSL router 'A' and my personal network hub to create a personal subnet on the 'B' outputs, and then connect the other Belkin 'C' input to the spare 'A' output to create an isolated tenant subnet on the 'C' outputs (obviously changing IPs and subnet masks to suit).

This would have resulted in 'A' out to 'B' in for 'personal' 'B' out nodes, and 'A' out to' C' in for 'tenant' nodes on 'C' outs, but this doesn't seem to be what you are suggesting, so could I sheepishly ask you explain the ins and outs of 'A', 'B', 'C' in greater detail for me please.