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DHCP on multiple interfaces

Scheduled Pinned Locked Moved DHCP and DNS
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  • J
    johnpoz LAYER 8 Global Moderator
    last edited by Sep 9, 2020, 5:28 PM

    You can create as many networks as you want.. If you want to put some of the devices that are currently on your lan network, on some other opt1 network sure that works..

    An intelligent man is sometimes forced to be drunk to spend time with his fools
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    D 1 Reply Last reply Sep 9, 2020, 5:45 PM Reply Quote 0
    • D
      danldn31 @johnpoz
      last edited by Sep 9, 2020, 5:45 PM

      @johnpoz Thanks. So pfsense will use both dhcp services(running on LAN and OPT1) allocate IP addresses accordingly?

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      • J
        johnpoz LAYER 8 Global Moderator
        last edited by johnpoz Sep 9, 2020, 5:48 PM Sep 9, 2020, 5:47 PM

        Yeah lan devices will get IPs from the lan dhcp pool, and devices in the opt1 network will be getting ips from that pool.

        Are none of your other networks using dhcp?

        Not understanding what the concern is here.. You clearly are running multiple networks, how is it you think you can only run 1 dhcpd pool?

        Your not wanting to run 2 different networks on the same L2 are you??

        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

        D 1 Reply Last reply Sep 9, 2020, 5:49 PM Reply Quote 0
        • D
          danldn31 @johnpoz
          last edited by Sep 9, 2020, 5:49 PM

          @johnpoz Other networks are wired. Not in DHCP

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          • J
            johnpoz LAYER 8 Global Moderator
            last edited by Sep 9, 2020, 6:06 PM

            @ddanielpala said in DHCP on multiple interfaces:

            Other networks are wired. Not in DHCP

            Huh?? What does wired or not have to do with dhcp? Your saying those other networks are all assigned static on the devices? Why? How many devices?

            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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            • D
              danldn31
              last edited by Sep 9, 2020, 6:15 PM

              Forget about other networks. What I am trying to achieve is to have two DHCP server on two different networks for clients to connect. Thanks.

              J 1 Reply Last reply Sep 9, 2020, 6:18 PM Reply Quote 0
              • J
                JKnott @danldn31
                last edited by Sep 9, 2020, 6:18 PM

                @ddanielpala said in DHCP on multiple interfaces:

                What I am trying to achieve is to have two DHCP server on two different networks for clients to connect.

                You can configure a DHCP server on every interface.

                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...

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                • J
                  johnpoz LAYER 8 Global Moderator
                  last edited by johnpoz Sep 9, 2020, 6:40 PM Sep 9, 2020, 6:34 PM

                  Yeah you could have 100's, shoot prob 1000s - depending on the umph of your hardware of networks and dhcp running on all of them.. I'm just a bit confused to how that is even a question.. Pfsense would be pretty freaking crappy if you could only run dhcpd on 1 network at a time ;) hehehe

                  So yeah, you can run multiple networks with dhcpd on any or all of them if you want.. Just click the little enable dhcp check box on the interface in the dhcp server section.

                  What you can not do, and people complain about it is run dhcpd and a dhcp relay.. You can either relay or be dhcp server.. You can not do both things at the same time, even on different networks.

                  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

                  D 1 Reply Last reply Sep 9, 2020, 6:58 PM Reply Quote 0
                  • D
                    danldn31 @johnpoz
                    last edited by Sep 9, 2020, 6:58 PM

                    @johnpoz Yes, so just thinking, if i have two such dhcp services running, will a personal device that connects to the wifi network get IP from second dhcp service that running on second interface. What changes need to be done to make that work.

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                    • J
                      johnpoz LAYER 8 Global Moderator
                      last edited by Sep 9, 2020, 7:02 PM

                      Huh... You said these would be different networks..

                      Please do not trying and run multiple layer 3 networks on the same Layer 2 network... That is just borked and cause you all kinds of issues.. Especially if any of these devices need to talk to each other..

                      If this is a single layer 2 network.. Then you NEED to change its ip range so you can increase network size to be appropriate for number of devices.. /23 or /22 - I really wouldn't put more than say a /22 on the same network.. Especially if they are chatty little window boxes that love to send out craptons of broadcasts and multicast..

                      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

                      D 1 Reply Last reply Sep 9, 2020, 7:12 PM Reply Quote 0
                      • D
                        danldn31 @johnpoz
                        last edited by Sep 9, 2020, 7:12 PM

                        @johnpoz I understand.
                        By network I meant two different subnets

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                        • J
                          johnpoz LAYER 8 Global Moderator
                          last edited by johnpoz Sep 9, 2020, 7:17 PM Sep 9, 2020, 7:14 PM

                          That is implied its 2 different L2 networks.. You do not run multiple L3 networks on the same L2 - its BORKED!! especially with 2 different dhcp servers..

                          Do what I suggested and move the IP range to something new so you can use a /22 or /23 network if you need more IPs on the same network.

                          edit: Don't tell me the other networks you mention are all on the same L2??? That is why your not running dhcp on them???

                          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

                          D 1 Reply Last reply Sep 9, 2020, 7:20 PM Reply Quote 0
                          • D
                            danldn31 @johnpoz
                            last edited by danldn31 Sep 9, 2020, 7:20 PM Sep 9, 2020, 7:20 PM

                            @johnpoz Yes, I think that's the right approach. Thank you.
                            Like I said, we have an unused interface OPT1, so I can just disable DHCP on LAN and enable DHCP on OPT1. We do have around 10-15 static mappings which then need to add it to the new DHCP interface.
                            After that, we will work on organizing our entire networks in a more proper way as @JeGr suggested.
                            Thank you

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                            • J
                              johnpoz LAYER 8 Global Moderator
                              last edited by johnpoz Sep 9, 2020, 7:24 PM Sep 9, 2020, 7:21 PM

                              So this is just one big flat network with multiple layer 3 networks on it.. OMG.. what a cluster..

                              Do you have switches that support vlans? Do you have multiple switches?

                              If all you want is 1 big network, then do that - there is no reason to run multiple layer 3 networks if all you have is one L2.. You are not actually isolating anything from talking to each other if al your doing is using different IP schemes for different clients. So you might as well just put them on 1 network.

                              To properly segment clients, you need to do it at layer 2 first..

                              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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