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Multiple DHCP subnet on one LAN interface

Scheduled Pinned Locked Moved DHCP and DNS
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  • J
    JKnott @sifti85
    last edited by Mar 4, 2025, 2:49 PM

    @sifti85

    Use VLANs. That's the normal way to have VoIP and regular stuff on the same LAN.

    PfSense running on Qotom mini PC
    i5 CPU, 4 GB memory, 32 GB SSD & 4 Intel Gb Ethernet ports.
    UniFi AC-Lite access point

    I haven't lost my mind. It's around here...somewhere...

    S 1 Reply Last reply Mar 4, 2025, 5:34 PM Reply Quote 0
    • J
      JKnott @Gertjan
      last edited by Mar 4, 2025, 2:52 PM

      @Gertjan said in Multiple DHCP subnet on one LAN interface:

      edit : your image makes me think there are two (DHCP) server bound to an (one and the same) interface. That's a big nono.

      Actually, DHCP supports that. When a device makes a DHCP request, it goes with the first server to respond. These days, Duplicate Address Detection (DAD) is used to ensure the same address isn't handed out to more than one device, but you might want to create separate address pools, within the subnet, for the different DHCP servers, just in case.

      PfSense running on Qotom mini PC
      i5 CPU, 4 GB memory, 32 GB SSD & 4 Intel Gb Ethernet ports.
      UniFi AC-Lite access point

      I haven't lost my mind. It's around here...somewhere...

      1 Reply Last reply Reply Quote 0
      • G
        Gertjan @sifti85
        last edited by Gertjan Mar 4, 2025, 2:55 PM Mar 4, 2025, 2:53 PM

        @sifti85

        Hummm.
        So just one pool in the 192.168.64.0/24 range,
        In that case, create a 192.168.0.1 whatever/16 interface IP on LAN;
        On the DHCP server page, add the 64.150->64.253 pool,
        Add your static DHCP MACs, the ones from 192.168.1.x and 192.168.68.y range.
        This might, no ! => should work.
        Use the ISC DHCP server if you use pfSense 2.7.2.

        @JKnott : ok for multiple DHCP servers.
        Also more then one pfSense DHCP servers running on the same interface ?

        No "help me" PM's please. Use the forum, the community will thank you.
        Edit : and where are the logs ??

        S 1 Reply Last reply Mar 4, 2025, 5:36 PM Reply Quote 0
        • U
          Uglybrian
          last edited by Mar 4, 2025, 3:31 PM

          What are you thinking in terms of PF Sense? Are you going to buy an appliance or try the community version? How big is your network,did you post the majority of it or is there alot behind that.

          S 1 Reply Last reply Mar 4, 2025, 5:44 PM Reply Quote 0
          • S
            sifti85 @JKnott
            last edited by Mar 4, 2025, 5:34 PM

            @JKnott said in Multiple DHCP subnet on one LAN interface:

            Use VLANs. That's the normal way to have VoIP and regular stuff on the same LAN.

            Unfortunately, VLAN is not a solution because many unmanaged switches in our environment do not support it.

            1 Reply Last reply Reply Quote 0
            • S
              sifti85 @Gertjan
              last edited by Mar 4, 2025, 5:36 PM

              @Gertjan said in Multiple DHCP subnet on one LAN interface:

              In that case, create a 192.168.0.1 whatever/16 interface IP on LAN;

              yes, but that would put them on the same subnet in practice. they could communicate with each other.

              1 Reply Last reply Reply Quote 0
              • S
                sifti85 @Uglybrian
                last edited by sifti85 Mar 4, 2025, 5:45 PM Mar 4, 2025, 5:44 PM

                @Uglybrian said in Multiple DHCP subnet on one LAN interface:

                What are you thinking in terms of PF Sense? Are you going to buy an appliance or try the community version? How big is your network,did you post the majority of it or is there alot behind that.

                Reply

                Community version only, Our network is small:
                50 PC
                10 VOIP DEVICE
                2 proxmox server(1 backup)
                11 IP CAMERA
                1 NVR
                5 Printer
                7 switch
                8 AP
                8 router
                max 10-20 wireless device at the same time.

                J 1 Reply Last reply Mar 4, 2025, 6:08 PM Reply Quote 0
                • J
                  johnpoz LAYER 8 Global Moderator @sifti85
                  last edited by Mar 4, 2025, 6:08 PM

                  @sifti85 just by some smart switches so you can use vlans like any normal person.

                  You have 8 APs - but only 10 or 20 wireless on at any given time?

                  You may well be able to continue to leverage your dumb switches downstream of a smart one, when all the devices on a switch are in the same vlan.

                  So in theory depending on your layout and connections you might be going through all this nonsense when a $20-40 smart switch could remove the nonsense of running multiple layer 3 on the same layer 2. Or maybe a couple of them?

                  Can you draw out your network showing where your switches are, and what devices are where.

                  8 router

                  That insane no small network like that would have need of 8 routers.. Are you calling your routers AP? And doubling the count?

                  An intelligent man is sometimes forced to be drunk to spend time with his fools
                  If you get confused: Listen to the Music Play
                  Please don't Chat/PM me for help, unless mod related
                  SG-4860 24.11 | Lab VMs 2.8, 24.11

                  S 1 Reply Last reply Mar 4, 2025, 6:19 PM Reply Quote 0
                  • S
                    sifti85 @johnpoz
                    last edited by sifti85 Mar 4, 2025, 6:21 PM Mar 4, 2025, 6:19 PM

                    @johnpoz

                    @johnpoz said in Multiple DHCP subnet on one LAN interface:

                    hat insane no small network like that would have need of 8 routers.. Are you calling your routers AP? And doubling the count?

                    ye routers function as an AP. and mostly several computers and printers are plugged into them.

                    J 1 Reply Last reply Mar 4, 2025, 6:48 PM Reply Quote 0
                    • J
                      johnpoz LAYER 8 Global Moderator @sifti85
                      last edited by Mar 4, 2025, 6:48 PM

                      @sifti85 so you have 8 APs then.. If they are not doing the router function of your typical soho wifi router, then they are just APs

                      Nothing wrong with doing that if that is what you have to work with.. If they are running 3rd party firmware like dd-wrt or openwrt they may very well support vlans and you might be able to just leverage them as your smart switches to allow for vlans on your network.

                      A diagram showing how everything is connected and what devices are on what L3 ip space.. It may be possible to segment your network correctly without having to purchase anything.

                      But again you do not need some Cisco enterprise $$$ switches do vlans - there are plenty of 20 to 40 dollar switches on the market that understand vlans.

                      An intelligent man is sometimes forced to be drunk to spend time with his fools
                      If you get confused: Listen to the Music Play
                      Please don't Chat/PM me for help, unless mod related
                      SG-4860 24.11 | Lab VMs 2.8, 24.11

                      S 1 Reply Last reply Mar 4, 2025, 7:53 PM Reply Quote 0
                      • S
                        sifti85 @johnpoz
                        last edited by Mar 4, 2025, 7:53 PM

                        @johnpoz said in Multiple DHCP subnet on one LAN interface:

                        A diagram showing how everything is connected and what devices are on what L3 ip space.. It may be possible to segment your network correctly without having to purchase anything.

                        Tomorrow i will do it.

                        S 1 Reply Last reply Mar 5, 2025, 12:56 PM Reply Quote 0
                        • S
                          sifti85 @sifti85
                          last edited by Mar 5, 2025, 12:56 PM

                          with zeroshell firewall I can create as many subnets on the native VLAN as I want :D how is this possible?
                          add_subnet.PNG
                          interface.PNG

                          J 1 Reply Last reply Mar 5, 2025, 1:45 PM Reply Quote 0
                          • J
                            johnpoz LAYER 8 Global Moderator @sifti85
                            last edited by Mar 5, 2025, 1:45 PM

                            @sifti85 you can do whatever you want - don't make it right, running multiple layer 3 Ip ranges on the same layer 2 is just nonsense.

                            An intelligent man is sometimes forced to be drunk to spend time with his fools
                            If you get confused: Listen to the Music Play
                            Please don't Chat/PM me for help, unless mod related
                            SG-4860 24.11 | Lab VMs 2.8, 24.11

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