This topic

2 routers

Bikeboardsurf — Tue, 18 Jul 2023 21:34:39 GMT

I currently have a residential BT home hub (router A) as the primary router and provides Internet connectivity. I have a second router that is NOT a home hub, lets call it router B. Router B is used for LAN traffic routing. Router B is plugged into an ethernet port of the home hub. Router B is on a different ip range compared to the home hub. How can I configure the home hub to route traffic based on ip address to router B . I have searched the settings but cannot find anything. I don't want to route using port forwarding, I want to route based on Ip range (regardless of port). Routers should be able to link two different networks.

Here is the example to illustrate the above:

HH - 192.168.1.X (255.255.255.0)

ROUTER B - 10.0.2.X (255.255.255.0)

DEVICE 1 (192.168.1.10) cannot reach DEVICE 2(10.0.2.5) .

Thanks for the help

Re: 2 routers

WSH — Tue, 18 Jul 2023 21:43:48 GMT

LAN port on the HH to WAN port on B. Wan port address needs to be in HH network.

Re: 2 routers

WSH — Tue, 18 Jul 2023 21:53:18 GMT

Oh...and if you are going to use 10. that subnet mask needs to be 255.0.0.0 for a private network.

Re: 2 routers

countrypaul — Tue, 18 Jul 2023 22:43:31 GMT

If he if going to use 10.0.2.x then his subnet mask at 255.255.255.0 is correct, if he was using 10.x.x.x then 255.0.0.0 would be appropriate.

Re: 2 routers

Crimliar — Tue, 18 Jul 2023 22:49:12 GMT

So what is it that our OP is trying to do?

It's far easier to have 2 or more subnets within the same reserved range, otherwise, you have to resort to creating rules which you just can't do on most ISP-provided equipment.

There are lots of what/why possibilities, so maybe some more info from the OP would be worthwhile!

Re: 2 routers

Bikeboardsurf — Wed, 19 Jul 2023 03:34:41 GMT

Thanks, but the issue will still be that the HH does not know how to direct traffic to Router B. The HH does not seem to have settings or an address/routing table to inform it to send 10.0.2.x to Router B

Re: 2 routers

TimCurtis — Wed, 19 Jul 2023 07:16:32 GMT

@Bikeboardsurf

I do something similar but use 192.168.2.1 for my SH2 and my network is the 192.168.1.xxx range as that how my setup was before I was forced to use the SH2 for Digital Voice.

All I do is set the SH2 to port forward everything (IPv4/6) to 192.168.1.1 which is my router. I use 255.255.252.0 as the subnet mask.

For the SH2 it's a firewall setting for IPv4 and pinholes for IPv6.

Works perfectly for me

Re: 2 routers

WSH — Wed, 19 Jul 2023 09:10:15 GMT

@countrypaul The problem is 10.0.2.x on 255.255.255.0 is a public as range. Using that in a private context has problematic written all over it and is considered bad practice. I suspect the HH may be funny about passing that over a LAN port. In fact, I'm surprised it allowed it at all.

Tim Curtis’ approach is the same as I use and works fine.

Re: 2 routers

countrypaul — Wed, 19 Jul 2023 09:58:53 GMT

All addresses within the 10.x.x.x range are private, that means you can have one network at 10.0.2.x and one at 10.0.1.x and a router linking them and also linking to the internet. The router should not forward any of the private addresses to the Internet. Not sure how many, if any, simple ISP supplied routers could handle that. The subnet mask it used to determine if a target address is on the local network or if it needs to be sent via a router.

I agree that Tim Curtis’ approach is probably amongst the best solution though.

Re: 2 routers

WSH — Wed, 19 Jul 2023 10:28:26 GMT

@countrypaul. Actually, you’re right now I think about it. Too used to seeing it used with 255.0.0.0 in workplaces.

I concede the point sir!

Re: 2 routers

Crimliar — Wed, 19 Jul 2023 16:40:19 GMT

It's still not clear what you are hoping to achieve through this segmentation!

With the primary router set

IP: 192.168.1.254/16 (255.255.0.0) and DHCP allocating say 192.168.1.16- 192.168.1.239 Gateway: 192.168.1.254

you could then set the secondary router (LAN to LAN connection) as:

IP: 192.168.2.254/15 (255.255.0.0) and DHCP allocating say 192.168.2.16-192.168.2.239 Gateway 192.168.1.254

Provided the routers are setup correctly they should be able to handle routing up to 255 local clients (it's built into the network controller chips).

*This should work, but it's a quirky way of doing things, and if it doesn't work it'll most likely be the case of whoever coded the router did not anticipate what you are trying to do.

Re: 2 routers

countrypaul — Wed, 19 Jul 2023 17:04:09 GMT

If you use 255.255.0.0 as the masks you will have trouble communicating between those on the first network with those on the second network. Anything in the 192.168.1.x network will think anything on the 192.168.2.x network is on their network and not use the router - similarly the for those on the 192.168.2.x network will not use the router to get to the 192.168.1.x network. The second DHCP server should not give out the 192.168.1.254 address as the gateway since that is in the first network and it won't find it as it does not know where the second router is. The second DHCP server should give the address of the second router (on the second network) as the gateway. That won't solve the problem of trying to communicate with nodes directly on the first network from the second network but would allow nodes on the second network to access the Internet. Packets from the internet might not make it to the second network as the first router (if using a 255.255.0.0 mask) would look for their destination on the local network rather than forwarding to the second router.

Re: 2 routers

Crimliar — Wed, 19 Jul 2023 20:06:04 GMT

You are connecting LAN port to LAN port, so you don't actually have two LANs. All you are doing is segmenting what is allocated via the DHCP server(s). Whether it works or not depends on how the code for the routers is written, but that second router is acting as little more than a switch. It ain't clever, but without knowing what the OP is trying to do, coming up with a clever solution is near impossible!

Re: 2 routers

Bikeboardsurf — Wed, 19 Jul 2023 21:33:46 GMT

Thanks for the posts.

I have a small lab running a Kubernetes cluster, when a service needs to be exposed (e.g a bespoke API, a web page, a web based application etc.) outside of the Kubernetes cluster, an IP address is created within a pre-agreed range (this range can be anything I configure it to be), MetalLB is used for this in conjunction with the router. But the range cannot clash with existing Ip addresses. Every time a new service needs to be exposed, a unique IP address needs to be assigned , clearly a lot of IP addresses will be generated so this limits the range i can configure, especially as I use the lab for research and development. So the original idea is to have a router handle those IP addresses while keeping the rest of the house household issued IP ddresses that are not relevant to the lab separate and not to mess about too much with the HH during what I'm doing on the lab cluster. The IP range for Router B can be any arbitrary value, it does not need to be 10.0.2.x. So to summarise I'm looking for the HH to be relatively stable by keeping it separate from the lab and I'd like the other router to do the hard work and ideally using an IP range that easily signifies that it is lab related.

Re: 2 routers

countrypaul — Wed, 19 Jul 2023 23:05:43 GMT

If you have 2 DHCP servers on the same Lan then it becomes a bit of a lottery as to which one will actually serve any request. I assumed the second router was there for that purpose of making sure there are 2 subnets so that DHCP requests are served by the relevant DHCP server.

The original request was that clients in the first subnet (from SH 192.168.1.x) could not see the addresses in the second subnet (router 2 10.0.2.x) - which could be achieved by using a router as a router and not just a switch. I presume this would require the WAN port on router2 to be connected to a Lan port on the SH2.

Re: 2 routers

Crimliar — Thu, 20 Jul 2023 06:04:10 GMT

At the point where a DHCP request is made, physical clients should receive a DHCP allocation from the device they are connecting to, and provided the LAN SSIDs are different the same should be true for WiFi clients. As said, it's messy, and does depend on the underlying software to work properly.

There is nothing in the original post that requests that clients in range one cannot see clients in range two!

Re: 2 routers

countrypaul — Thu, 20 Jul 2023 08:23:16 GMT

Ah, I read that first post in a different way, when op wrote:

DEVICE 1 (192.168.1.10) cannot reach DEVICE 2(10.0.2.5) .

I took that as a requirement, in that he did wanted devices in the 192.168.1.x subnet to not have access to the 10.0.2.x subnet. Re - reading that post, I can see it as either a requirement or a problem with his setup.

Re: 2 routers

Crimliar — Thu, 20 Jul 2023 15:54:08 GMT

I've been toying this around my head all day, and it's still beyond messy. The first time you get a DHCP broadcast it'd probably all fall down even if everything else was in place. It'd be much easier if you abandon the BT router altogether, preferably (and I hate to say this) use a pFsense or oPensense router using a large IP range (MetaILB doesn't need a full subnet to itself). You might still need to recompile the DHCP daemon, and use a short TTL (Time To Live) for the IP tables.

Beyond that, getting advice from the MetaILB or Kubernetes communities is probably best!