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    Is this how prefixes work?

    Scheduled Pinned Locked Moved IPv6
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    • S
      smk
      last edited by smk

      Running pfSense Plus 24.03

      LAN ipv6 set to track the WAN. I have prefix delegation set to /56 and getting IPv6 from the ISP.

      I was expecting my LAN computers to get address: 2605:e000:7fc0:6b00:xxxx:xxxx:xxxx:xxxx , but instead LAN computers are getting: 2603:8001:3400:4a00:xxxx:xxxx:xxxx:xxxx

      I was expecting that LAN assignment because assignment from ISP is: 2605:e000:7fc0:6b:xxxx:xxxx:xxxx:xxxx

      I have Router Advertisement turned on and set to unmanged and DHCPv6 turned off.

      Shouldn't the LAN addresses follow the ISP assignment?

      My ISP is Spectrum in SoCal

      Thanks in advance!

      johnpozJ JKnottJ 4 Replies Last reply Reply Quote 0
      • johnpozJ
        johnpoz LAYER 8 Global Moderator @smk
        last edited by

        @smk your delegated prefix doesn't have to be inline with the IPv6 your wan actually gets on it.. The prefix is just routed to you via the transit you have on your wan.

        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

        1 Reply Last reply Reply Quote 1
        • S
          smk
          last edited by

          Thanks @johnpoz

          I think I am getting a prefix delegation of /56 because I have an IPv6 on WAN and everything seems to work. But how can I really be sure what prefix the ISP is assigning?

          System Logs -> DHCP and filtering by dhcp6c does not show the ISP assigned prefix

          johnpozJ 1 Reply Last reply Reply Quote 0
          • johnpozJ
            johnpoz LAYER 8 Global Moderator @smk
            last edited by

            @smk there was a thread before about this asking where to see what is actually delegated.. You could always just sniff and see what is delegated to you..

            Yeah you can for sure be delegated a /56, but that doesn't mean its going to be in the same /56 as you wan IPv6 address.

            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

            1 Reply Last reply Reply Quote 1
            • tinfoilmattT
              tinfoilmatt
              last edited by

              It's possible that your WAN interface has recevied a GUA from within the 2605:e000:7fc0:6b00::/64 prefix (i.e. 2605:e000:7fc0:6b00:xxxx:xxxx:xxxx:xxxx/128). And the tracked LAN interface has been assigned the 2603:8001:3400:4a00::/56 delegated prefix.

              DHCP logs would confirm or refute.

              1 Reply Last reply Reply Quote 1
              • johnpozJ
                johnpoz LAYER 8 Global Moderator @smk
                last edited by

                @smk this thread I recalled where talking about viewing the delegated prefix

                https://forum.netgate.com/topic/189392/where-in-the-interface-is-an-interface-s-ipv6-prefix-delegation-pd-shown

                You should be able to look in the dhcp log when your wan gets the delegation to see the specifics of what prefix was delegated to 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

                1 Reply Last reply Reply Quote 1
                • JonathanLeeJ
                  JonathanLee
                  last edited by

                  You should take that free hurricane electric tunnel broker ipv6 class. You get a T-shirt I think too.

                  Make sure to upvote

                  johnpozJ 1 Reply Last reply Reply Quote 2
                  • johnpozJ
                    johnpoz LAYER 8 Global Moderator @JonathanLee
                    last edited by

                    @JonathanLee Yup its a great run through of different aspects of IPv6.. And yup the free t-shirt is just a nice bonus for making it to sage level.

                    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

                    1 Reply Last reply Reply Quote 2
                    • S
                      smk
                      last edited by smk

                      My logs can't seem to confirm what prefix is being delegated by the ISP, although after setting /56 in pfsense configs everything seems to work fine.

                      Does this mean pfsense is getting a /128?
                      9d0aa4a4-8c80-4e1f-8b06-5c365f163b62-image.png

                      And nothing in the DHCP logs:
                      Sep 25 07:36:26 dhcp6c 79849 no responses were received
                      Sep 25 07:36:25 dhcp6c 79849 no responses were received
                      Sep 25 07:36:12 dhcp6c 79849 Sending Release
                      Sep 25 07:36:11 dhcp6c 79849 Sending Release
                      Sep 25 07:36:04 dhcp6c 79849 Sending Release
                      Sep 25 07:36:04 dhcp6c 79849 Sending Release
                      Sep 25 07:36:01 dhcp6c 79849 Sending Release
                      Sep 25 07:36:00 dhcp6c 79849 Sending Release
                      Sep 25 07:35:59 dhcp6c 79849 Sending Release
                      Sep 25 07:35:59 dhcp6c 79849 Sending Release
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2605:e000:7fc0:6b:a056:3221:e365:83e1/128 on mvneta0
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2603:8001:3400:4a02:2e0:edff:fec4:b04e/64 on mvneta1.2
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2603:8001:3400:4a03:2e0:edff:fec4:b04e/64 on mvneta1.3
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2603:8001:3400:4a04:2e0:edff:fec4:b04e/64 on mvneta1.4
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2603:8001:3400:4a94:2e0:edff:fec4:b04e/64 on mvneta1.4084
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2603:8001:3400:4a93:2e0:edff:fec4:b04e/64 on mvneta1.4083
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2603:8001:3400:4a92:2e0:edff:fec4:b04e/64 on mvneta1.4082
                      Sep 25 07:35:58 dhcp6c 79849 add an address 2603:8001:3400:4a00:2e0:edff:fec4:b04e/64 on mvneta1.4081
                      Sep 25 07:35:58 dhcp6c 79849 dhcp6c Received REQUEST
                      Sep 25 07:35:58 dhcp6c 79849 Sending Request
                      Sep 25 07:35:58 dhcp6c 79849 Sending Solicit
                      Sep 25 07:35:58 dhcp6c 79849 remove an address 2603:8001:3400:4a02:2e0:edff:fec4:b04e/64 on mvneta1.2
                      Sep 25 07:35:58 dhcp6c 79849 remove an address 2603:8001:3400:4a03:2e0:edff:fec4:b04e/64 on mvneta1.3
                      Sep 25 07:35:58 dhcp6c 79849 remove an address 2603:8001:3400:4a04:2e0:edff:fec4:b04e/64 on mvneta1.4
                      Sep 25 07:35:58 dhcp6c 79849 remove an address 2603:8001:3400:4a94:2e0:edff:fec4:b04e/64 on mvneta1.4084
                      Sep 25 07:35:58 dhcp6c 79849 remove an address 2603:8001:3400:4a93:2e0:edff:fec4:b04e/64 on mvneta1.4083
                      Sep 25 07:35:58 dhcp6c 79849 failed to remove an address on mvneta1.4082: Can't assign requested address
                      Sep 25 07:35:58 dhcp6c 79849 remove an address 2603:8001:3400:4a00:2e0:edff:fec4:b04e/64 on mvneta1.4081
                      Sep 25 07:35:58 dhcp6c 79849 Sending Release
                      Sep 25 07:35:58 dhcp6c 79849 Start address release
                      Sep 25 07:35:58 dhcp6c 79849 remove an address 2605:e000:7fc0:6b:a056:3221:e365:83e1/128 on mvneta0
                      Sep 25 07:35:58 dhcp6c 79849 Sending Release
                      Sep 25 07:35:58 dhcp6c 79849 Start address release
                      Sep 25 07:35:58 dhcp6c 79849 restarting

                      I mean to take that class over the weekend! Thank you for telling me.

                      1 Reply Last reply Reply Quote 0
                      • JKnottJ
                        JKnott @smk
                        last edited by

                        @smk said in Is this how prefixes work?:

                        I was expecting my LAN computers to get address: 2605:e000:7fc0:6b00:xxxx:xxxx:xxxx:xxxx , but instead LAN computers are getting: 2603:8001:3400:4a00:xxxx:xxxx:xxxx:xxxx

                        Entirely normal. The WAN prefix has nothing to do with your LAN.

                        @smk said in Is this how prefixes work?:

                        But how can I really be sure what prefix the ISP is assigning?

                        Well, if you really want to be sure, capture your DHCPv6 sequence and examine the capture with Wireshark. However, you can be fairly certain that whatever prefix is on your LAN is what your ISP has assigned you.

                        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 1
                        • JKnottJ
                          JKnott @smk
                          last edited by

                          @smk

                          Here are a couple of other points:

                          A WAN interface doesn't actually need a public address. With IPv6, routing is often done with the link local address.

                          That /128 prefix length means there's no actual subnet there. That address is nothing more than a label for your router.

                          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 1
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