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DHCP for different LANs

GTINetworksGTINetworks Newbie ✭
in Entry Level Firewalls

I have a TZ400 with our office LAN subnet, 192.168.1.0/24, on port X0. That LAN has a DHCP server running on Microsoft Server 2019.

I need to add 192.168.2.0/24 to port X2. I would like to use the built in DHCP server on the TZ400 for that LAN subnet but I don't want to conflict with the DHCP server on X0. Can I do that without causing a conflict? How does the Sonicwall know to only respond to DHCP requests on X2?

Thank you, Kevin

Category: Entry Level Firewalls
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  • shiprasahu93shiprasahu93 Moderator

    Hello @GTINetworks ,

    Yes, you can certainly add another DHCP scope without conflicting with the X0 DHCP scope.

    Every DHCP scope is bound to an interface as below.

    dhcp scope.png

    So, if you disable the checkbox for X0, whenever a DHCP request is made on X0, the SonicWall cannot assign an IP. But the same will continue to work on X2.

    So, X2 needs to be on a static IP eg: 192.168.2.1/24 and then add a dynamic DHCP scope for X2 and keep the same disabled for interface X0.

    Please, let me know if you have any additional queries.

    Thanks!

    Shipra Sahu

    Technical Support Advisor, Premier Services

  • SaravananSaravanan Moderator
    Hello @GTINetworks,

    Yes, you can have DHCP scope configured and enabled on the SonicWall for X2 LAN without conflict to existing X0 LAN. All that we need to do is to configure DHCP scope on the SonicWall for only X2 subnet 192.168.2.0/24. I presume you don't have DHCP scope on the SonicWall for X0 interface based as your Microsoft Server takes care of it.

    Please refer below KB article instructions for DHCP dynamic scope creation on SonicWall.

    https://www.sonicwall.com/support/knowledge-base/configuring-the-dhcp-server-on-the-sonicwall/170505423294713/#:~:text=The%20SonicWall%20security%20appliance%20includes,SonicWall%20security%20appliance's%20DHCP%20server.

    Regards

    Saravanan V

    Technical Support Advisor - Premier Services

    Professional Services

  • Stuart_WestStuart_West Newbie ✭
    As the moderators have pointed out, it's a trivial task to set up a DHCP scope for your X2 network. You just need to be sure that you have the rest of your network separated correctly, so that your clients pick up the correct DHCP address. Typically, if you have separate switches for the two zones, use a new network and set up as described above. If you are planning on using a single switch for both networks, you'll likely need to set up a VLAN interface on the Sonicwall and tie your DHCP scope to that. You don't necessarily need to tie anything to the X2 interface or patch in a separate cable. Any traffic that hits X0 that's tagged with your VLAN will get a DHCP address from your Sonicwall. Otherwise, it will function identically to how it's described above.
  • SaravananSaravanan Moderator

    @STUART_WEST - Thanks for the add on point of single switch usage scenario 🙂

    Regards

    Saravanan V

    Technical Support Advisor - Premier Services

    Professional Services

  • GTINetworksGTINetworks Newbie ✭

    Thank you very much for all of your excellent answers.

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