I would like to create a network like the one in the screenshot. I would have 2 VLANs :
-VLAN10 : Service1
-VLAN20 : Service2

Routing is working but i don't know if I can have adresses on 192.168.1.X behind both routers. Because on both routers my FA0/0 needs to be reachable by each machine.

For exemple on the left, and need to be able to reach the gateway, but they are not on the same subnet, so how is it possible ? And even if this is possible, if I want to ping, will send ARP requests since it is the same subnet, and he won't try to reach the gatway. Dots are red because i did the screenshot while packet tracer was starting but routing is done.

Thank you in advance for your help :)

enter image description here

  • 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 could provide and accept your own answer.
    – Ron Maupin
    Aug 17, 2017 at 3:45

1 Answer 1


As you've drawn this, you can't do it. You can't have the same subnet in two locations (separated by a layer 3 link).

To make this work, you need 4 VLANS, two at each site. You can make the ones on the left and, and the ones on the right and

The lower two routers will have a subinterface on each VLAN/subnet. The switch will trunk both VLANs to the router. You can apply any security filtering to the /24 block as needed.

If this were a real network, ask yourself why would you need to have the same subnet in both locations? There are rarely any strong reasons for doing so.

  • well you could with VxLAN but I guess this is not the purpose here ;)
    – JFL
    Mar 3, 2017 at 17:07
  • Thank you very much for your answer. Effectively it answers to my question. Now i'd like to know how would the DHCP be able to deliver the right IP addresses depending on the VLAN 'asking' him ? And imagine I have a service of 50 people working on different buildings in a company site. I thought it was possible to make them all on the same subnet, even across routers. Mar 3, 2017 at 22:11

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