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Here is what the network looks like:

Network A is 192.168.116.X , subnet 255.255.255.0 
Network B is 12.32.8.X , subnet 255.255.255.0

There are no routers present in either of the network schemes. All routing is done through unmanaged switches and hubs. Both networks are peer-to-peer and do not rely on DHCP. All machines have static IPs.

I need any machine on Network B to be able to reach any node on Network A

Eminent
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  • is it desirable for you to assign secondary IPs on the machines in both networks ? – Mr.lock Nov 14 '16 at 08:35
  • Yes, that would be ideal but there are no extra NICs and it is not feasible to install a new PCI network interface card in these machines. – Eminent Nov 14 '16 at 09:37
  • What operating system are the machines running? Depending on the operating system you may be able to add an alternate address on the same NIC. – 3iron Nov 14 '16 at 11:44
  • I think this is a networking problem. There are many ways to solve this. The OP didn't ask how to configure his hosts. – Ron Trunk Nov 14 '16 at 15:59
  • What software are the machines running? do they have a default gateway set? if so what is it set to? is purchasing new equipment possible? Is there a server that could be used as a router? – Peter Green Nov 14 '16 at 17:24
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer. – Ron Maupin Jan 04 '21 at 22:59

3 Answers3

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You have two layer 3 domains, but no layer three devices. That's a problem.

You can bridge the networks together, but bridging happens at layer 2. It does not change the fact that you have two IP subnets.

I see only three real possibilities, in descending preference.

  1. Buy a router to route between the subnets.
  2. Readdress one or both of the subnets to a common IP subnet.
  3. Configure secondary addresses on both devices for a common subnet.

Maybe other readers have more ideas.

Ron Trunk
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Add a secondary IP address to each NIC card. The primary being in 192.168.116.X and the secondary being in 12.32.8.X. Or, the other way around - it does not matter which one is secondary as long as each NIC has an address on both subnets.

You do not need a second NIC card. This secondary IP address is added/configured in software.

Ronnie Royston
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Since all being static: Proxy ARP

Jaap Keuter
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  • Since there are no Cisco devices, I don't see how this is possible. – Ron Trunk Nov 14 '16 at 13:57
  • Who's talking about available devices? There's no mention of not adding devices or changes to the networks. Who's talking about Cisco devices? The mere fact that the link refers to a page which explains the Proxy ARP concept doesn't mean that the supplier hosting the page is the only solution provider. – Jaap Keuter Nov 14 '16 at 14:56
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    There are no managed devices in the network. If the OP is going to add a new device, then he can simply route without having to use proxy arp. – Ron Trunk Nov 14 '16 at 15:34