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    Comcast gateway LAN/router LAN conflict?

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    • JaredBuschJ
      JaredBusch
      last edited by

      @frodooftheshire here is a good description form AT&T on the subject of IP passthrough. It is basically the same for Comcast. They are not going to route two networks to every basic business customer in order to let you truly have your own full public IP.

      IP Passthrough means the AT&T supported CPE device terminates the DSL, authenticates with the network (Receives a WAN IP) and shares that IP address with a single device connected to the AT&T supported CPE equipment. This configuration is often times suitable for a business customer desiring to connect third party equipment to AT&T supported equipment. The "IP Passthrough configuration still allows AT&T support groups to access the AT&T supported equipment while allowing end-users to connect third party equipment in a configuration they desire. The "IP Passthrough" configuration will only allow one connection to AT&T supported equipment to be "unfiltered" or pingable from the WAN or internet side of the AT&T equipment (does not support multiple pingable connections).

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      • scottalanmillerS
        scottalanmiller @frodooftheshire
        last edited by

        @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

        @travisdh1 Just to be clear...the router is configured for a WAN static IP from comcast, so the IP address on the routers WAN is different from the router's LAN.

        The IP is different, but is the network different? What's the subnet?

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        • F
          frodooftheshire @scottalanmiller
          last edited by frodooftheshire

          @scottalanmiller Sorry, I should have been more clear there. The static IP on the luxul's WAN side is 50.193.X.X /30. The lan side on the Comcast is 10.1.10.0/24 and the lan on the Luxual is the same 10.1.10.0/24

          JaredBuschJ travisdh1T 2 Replies Last reply Reply Quote 0
          • JaredBuschJ
            JaredBusch @frodooftheshire
            last edited by

            @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

            @scottalanmiller Sorry, I should have been more clear there. The static IP on the luxul's WAN side is 50.193.X.X /30.

            it is not a static IP

            @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

            The lan side on the Comcast is 10.1.10.0/24 and the lan on the Luxual is the same 10.1.10.0/24

            this is completely the problem.

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            • travisdh1T
              travisdh1 @frodooftheshire
              last edited by

              @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

              @scottalanmiller Sorry, I should have been more clear there. The static IP on the luxul's WAN side is 50.193.X.X /30. The lan side on the Comcast is 10.1.10.0/24 and the lan on the Luxual is the same 10.1.10.0/24

              Time to try my ASCII art so we can visualize this:

                 Comcast          Luxual           Local Net
              10.1.10.0/24 --> 50.193.x.x/30  --> 10.1.10.0/24
              

              I'd say you need to change the local subnet or get a new subnet from Comcast, either way works. Probably easier to change the Local Net.

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              • F
                frodooftheshire @travisdh1
                last edited by frodooftheshire

                @travisdh1 it's way easier to change the LAN subset on the Comcast which a is a quick fix. The long term fix would be to change the LAN IP scheme behind the luxul. They have a lot of misc devices with static IPs on the LAN that would all have to get updated.

                travisdh1T 1 Reply Last reply Reply Quote 0
                • F
                  frodooftheshire @JaredBusch
                  last edited by

                  @JaredBusch They pay for a dedicated static IP from Comcast. What would you call it if not a static IP?

                  travisdh1T JaredBuschJ 2 Replies Last reply Reply Quote 0
                  • travisdh1T
                    travisdh1 @frodooftheshire
                    last edited by

                    @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

                    @travisdh1 it's way easier to change the LAN subset on the Comcast which a is a quick fix. The long term fix would be to change the LAN up scheme behind the luxul. They have a lot of misc devices with static IPs on the LAN that would all have to get updated.

                    I generally avoid calling Tier 1 support from my ISP whenever possible, it always feels like walking into the dragon's lair.

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                    • travisdh1T
                      travisdh1 @frodooftheshire
                      last edited by

                      @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

                      @JaredBusch They pay for a dedicated static IP from Comcast. What would you call it if not a static IP?

                      Can you ping that 50.193.x.x address from outside your local network?

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                      • F
                        frodooftheshire @travisdh1
                        last edited by

                        @travisdh1 yes. I can ping the Comcast's gateway IP and the usable IP configured on the router.

                        travisdh1T 1 Reply Last reply Reply Quote 0
                        • travisdh1T
                          travisdh1 @frodooftheshire
                          last edited by

                          @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

                          @travisdh1 yes. I can ping the Comcast's gateway IP and the usable IP configured on the router.

                          From outside your local network? You shouldn't be able to reach the 10.1.10.X subnet as it's a private IP range.

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                          • F
                            frodooftheshire @travisdh1
                            last edited by

                            @travisdh1 The usable WAN ip address that's configured on the WAN side of the router.

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                            • F
                              frodooftheshire
                              last edited by

                              Just to clarify, here in Oregon when you pay for a static IP address from Comcast (either a single or in a block of 5) you have the gateway's public IP address, then the usable public static IP address that you can assign to your router.

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                              • F
                                frodooftheshire
                                last edited by frodooftheshire

                                alt text

                                Just imagine this, but with the LAN subnet on the Comcast gateway to be idential to the LAN side of the linksys router.

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                                • stacksofplatesS
                                  stacksofplates
                                  last edited by stacksofplates

                                  Don't get hung up on the static address. I think he was assuming you had DHCP. You either need to change the subnet on the Comcast gateway or the Luxul router.

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                                  • JaredBuschJ
                                    JaredBusch @frodooftheshire
                                    last edited by

                                    @frodooftheshire said in Comcast gateway LAN/router LAN conflict?:

                                    @JaredBusch They pay for a dedicated static IP from Comcast. What would you call it if not a static IP?

                                    A fixed IP.

                                    It is of course possible that Comcast is using a a true static IP assignment. But it is unlikely.

                                    If it was a true static, then your comcast modem will have another public WAN IP and the /30 you have is routed behind that.

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