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    SG-3100 should I use OPT1 as the main LAN port?

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    • C
      ChrisJenk
      last edited by

      I've just bought an SG-3100. I see that the two 'main' GigaBit ports are labelled WAN and OPT1. I also see that it has 4 GigaBit 'LAN' ports. My understanding is that the 4 'LAN' ports are connected to an internal switch with a maximum (shared) bandwidth of 2.5 Gbps (is that correct?), while the WAN and OPT1 ports are full 1 Gbit ports. Since I will never have any need for dual-WAN, does it make the most sense to make the primary LAN connection (through which all my traffic to/from the Internet will flow) the OPT1 port rather than 1 of the LAN ports?

      Any pros or cons in doing this versus using one of the LAN ports as the connection for the main LAN?

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      • M
        mer @ChrisJenk
        last edited by

        @chrisjenk
        I'm not sure about the bandwidth on the LAN port, but that is probably the bandwidth "up" from the switch. Documentation says the LAN ports are all on the same switch device, so it's possible the 2.5G is a correct figure.

        But a couple of questions (and my opinions):
        Your WAN port, is it greater than 1G? If not, then that's the bottleneck and it really doesn't matter the speeds the rest of the network.

        Are you planning on plugging more than 2 devices directly into the LAN ports of the 3100? If not, then the maximum into the LAN port is 1G if you have a 1G switch down from it.

        Are you planning on having a switch downstream from the 3100, even if plugged into the OPT1 port? If so, you wind up being limited by the speed of the switch.

        The "up from the switch" bandwidth really only matters if you configure the LAN ports on different subnets and you are planning on trying to stream 1G simultaneously from all the ports.
        Typical network traffic has lots of gaps in it, so the upstream bandwidth from the switch really doesn't matter.

        My personal opinion, is don't worry about the upstream bandwidth from the LAN switch, configure the VLANs so you can have separate subnets.

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        • C
          ChrisJenk @mer
          last edited by

          @mer Currently my WAN connection is 500 Mbit/s but soon it will be 1 Gbit/s and I don't want to risk any throttling on that. I will likely connect a few pieces of equipment to the built in switch ports on the SG-3100 (I don't need separate subnets on those ports - they will all be on the main LAN subnet - so no VLAN config needed on those) and some of those might have high traffic from time to time but I would rather they potentially get a bit throttled than have Internet traffic throttled.

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            mer @ChrisJenk
            last edited by

            @chrisjenk
            That sounds like a reasonable plan.
            Just remember that all the LAN ports on the switch are by default in the same VLAN (think like an unmanaged switch), so make sure you don't create a network loop (if you put another unmanaged switch downstream that you plug say LAN1 and LAN2 into).

            Any home network with more than one user endpoint (phone, PC, etc) has the potential to require more bandwidth than you get from the upstream ISP. Keep in mind "upstream vs downstream". Most home network traffic is downstream (people watching youtube, surfing the web) so your home network can't see more than the downstream WAN speed.
            If your home network is sending a lot upstream, you are always governed by upstream WAN speed.

            For the longest time, businesses survived on having 10/100Mbs internally with say a T1 (1.544Mbs) to the world. Until one gets symmetric 10Gbs my opinion is don't worry about it.

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            • C
              ChrisJenk @mer
              last edited by

              @mer Thanks, I am aware of those points. My setup won't have any switches connected to the other LAN ports, just the main LAN port (OPT1) connected to my main managed switch. I fully take your point about asymmetric speed on the WAN etc. Still, it seems to me best to use OPT1 for the main LAN interconnect and the other 4 ports just to connect odds and ends of equipment that happen to located close to the SG-1000 and where the shared 2.6 Gbps uplink capacity won't be a problem.

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              • stephenw10S
                stephenw10 Netgate Administrator
                last edited by

                I did quite a lot of testing on this recently and there is no significant difference between LAN and OPT for throughput to/from WAN.
                However I use OPT as my main connection here just because I also have it connected to an external switch and it makes changing VLANs on that link a lot easier.

                You may have no VLANs now but if you have a 1G connection and a number of devices using it you'll probably want to start segregating them at some point.

                Steve

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