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Here is my test network I'm trying to setup so Router A's Windows computer (192.168.1.2) can communicate with Router C's Windows computer (192.168.3.2):

Test schematic

Ping would be nice to start, but I also need DNS so I can just enter the name of the server behind either Router A or Router C. Essentially I need the /24 network to talk with the /30 network. Talking with the /28 network would be good but not needed. I'm using static IPs to keep everything simple.

The 10.1.0.0 network is my primary network.

I appreciate any help!

JeffR
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  • This is pretty much one of the simplest routing setups you can have in a network, what's the problem? – Lenniey Mar 07 '19 at 16:40
  • Yes, that's what I was going for. :) The problem is 192.168.1.2 cannot ping 192.168.3.2, let alone communicate with it. – JeffR Mar 07 '19 at 16:50
  • Well if you didn't configure the _routing_, they won't communicate. First of all, if you don't need the layer 3 routers A and C, you can achieve what you want on only router B if you use e.g. port based VLANs. – Lenniey Mar 07 '19 at 16:55
  • Oh ok. I don't want to use VLANs at this point. So here is the routing entry on Router A. What IPs and mask do I put in the fields? [Routing Form Entry](https://i.imgsafe.org/15/151c14b72a.jpeg) – JeffR Mar 07 '19 at 17:17
  • I've tried adding a static routes, but I still can't ping 192.168.3.2 computer. On Router A, [I tried this one](https://i.imgsafe.org/18/18c5068b4f.jpeg) and [I tried this one](https://i.imgsafe.org/18/18c9e6a5b7.jpeg), neither allow me to ping 192.168.3.2 from 192.168.1.1 or vice versa. Am I missing something obvious? – JeffR Mar 07 '19 at 21:27
  • 192.168.1.2 can ping all the 192.168.2.x IPs no problem, even the 192.168.2.3, which is the WAN connection of Router C. And 192.168.3.2 can ping all of the 192.168.2.x IPs no problem, even the 192.168.2.2, which is the WAN connection of Router A in the 'Test Schematic' above. – JeffR Mar 07 '19 at 21:29
  • I can immediately see that you have the wrong subnet mask on several machines. For example, the machine on the bottom right has 192.168.3.2 with a subnet mask of 255.255.252.0. That will make the machine think that 192.168.2.4 is in the same subnet as it is, and it won't send traffic for that IP address to the router because it doesn't know it needs to be routed. So it won't be able to ping 192.168.2.4. Oops. Fix the subnet masks first so that each subnet has a consistent mask for every machine in that subnet. – David Schwartz Mar 07 '19 at 23:26
  • Not sure what you mean. 192.168.3.2 _can_ ping 192.168.2.4 (and .1, .2, and .3 also). – JeffR Mar 08 '19 at 13:58

1 Answers1

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I think you've fundamentally misunderstood how routers work. You may be trying to utilize routers as switches which is unnecessary. In which case, you'd only need 1 router and three 'vlans' on it with three ports leading off to the PCs or a switch for multiple PCs.

If you do actually need multiple routers, you'd want one 'inter router network' and three 'client' networks. See diagram below: enter image description here

Edit: I just realized my diagram is very similar to yours. I think the problem may be that you're mixing up subnet masks inside the 'client' networks. The Net1 subnet mask should be consistent between the router interface and client, e.g. both should be 255.255.255.0 in my example.

Edit2: Oh I see what you're doing. You're using a commercial integrated hub/router and misunderstanding the way the WAN/LAN ports work. The WAN port is the only "router" port on a WRT54G. The LAN ports only act as a switch/hub. There would be no way for you route from a LAN port. The top level router would need to have multiple WAN ports with each of the lower ports connected to it. The WAN port acts "external" to the LAN ports because it's on the opposite side of the 'router' portion of the device.

Edit3: This may be an XY problem. If you're just trying to make a big network for a LAN party, the easiest thing would be to run a cable from a LAN port on each device to another. Then they all share the same 'network'. Disable DHCP on all but one of the 'routers' so that they don't conflict with each other.

Edit4: If you really want to do the routing thing, connect the WAN ports of the two "Lower" routers to the LAN ports of the "upper" router. The 'upper' router will give DHCP assignments to the WAN interfaces of the lower routers and the clients can connect to the "lower" routers with a different IP space. The "upper" router WAN port can be connected to internet.

duct_tape_coder
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  • Thank you for your reply. Yes, I do have the WAN ports on the WNR2000 routers connected to the LAN ports on the WRT54G. I'm trying to replicate a customer issue where they have one subnet at 255.255.255.0 and another at 255.255.254.0, and I need the computers on both subnets to talk to each other. I'm trying to put something together simple to replicate this. – JeffR Mar 08 '19 at 13:56
  • Edit1: Your "Edit 4" is _exactly_ what I was trying to do. The 10.1.x.x address connects to the "main" network which can get out to the internet. I just need the PCs behind RouterA & RouterC to be able to communicate with each other. Perhaps there is a inexpensive set of two routers I can use? – JeffR Mar 08 '19 at 14:01
  • Consumer "Routers" combine a lot of different networking techs together for consumer safety and simplicity. Your problem with accessing A and C from B is that A and C are behind NAT firewalls. It's not routing in the traditional sense. I don't know if those products have features to disable the NAT but you can usually create port forwards for particular applications. You'll need to go into Router A and tell it to forward port X to Client A (192.168.1.2), where X is the port for whatever you're trying to do. It won't be a good comparison for enterprise routing however. – duct_tape_coder Mar 08 '19 at 15:30
  • Would the dlink DSR-250s work instead and then I can just connect them direct? – JeffR Mar 08 '19 at 15:45
  • Sorry I don't know the answer. You'll need to look at the specific products and whether or not it allows you to disable NAT or Firewall. You can usually get refurbished or old cisco routers decently cheap if you want to experiment with 'proper' routing. – duct_tape_coder Mar 08 '19 at 17:21
  • So I need to disable NAT on both routers? How does NAT get sent between the subnetworks? – JeffR Mar 08 '19 at 18:54
  • In your Edit4, do I need to enter a static route for RouterA and RouterC so they can receive packets? I think I might be getting tripped up on the masks. – JeffR Mar 08 '19 at 19:44
  • I may be thinking incorrectly. The NAT is what allows the routing between the two subnets (WAN and LAN). Try just disabling the firewall feature and see if you can hit a LAN IP from the WAN side. – duct_tape_coder Mar 09 '19 at 19:45