I'm working through a tricky situation getting a field office set up out in a very rural area. There are ten 12' x 60' trailers being set up (2-3 metres apart from one another), each with varying amounts of staff working during the day (40-50 people total). There is no landline internet (cable / DSL / fibre) available, so we are forced into selecting LTE or Satellite services for our primary connection.

At present, we have a 100ft cell tower / booster in place, so the field yard is bathed in LTE signal (~25/5 mbps). The office administration has ordered ten LTE hubs, one per trailer, which each have three LAN ports and will broadcast a WiFi signal as well.

Now - the tricky part.

Project administrators have asked me to install a network for the office, with a few requirements:

1) Must be able to print to network-connected printers in the trailers, though not every trailer has one. May need to send jobs to the next building over, or someplace else.

2) All ten trailers must be able to access the temporary file server in place (a QNAP T-251+) by mapping the network drive in Windows / Mac (SMB)

3) The network must provide internet service as well such that the QNAP can back up its files to online storage; it is not an option to build a local-only network that people have to jump between when accessing the print/file equipment or the internet.

Obviously, this isn't an ideal setup, as each of those LTE hubs functions as its own router / network, and I have yet to find a ten-port load balancer that would be viable within the scope of this project. Has anyone run into this kind of challenge before and managed to come out the other side of it with one, cohesive network? I've been told to look into smart / managed switches that can run through some L3 routing capabilities of their own, but I'm not quite sure how to tie the whole thing together.

  • 1
    Why 10 LTE hubs instead of just outdoor grade cable connecting the trailers and one LTE hub for internet? – Todd Wilcox Aug 10 at 20:09
  • @ToddWilcox - The cell tower will only push the set speeds out, but the pipe is quite 'wide' in the sense that all ten hubs will get 15/5(ish), but a single hub will only see the same speeds. As advertised - very rural. If we connected a traditional switched network to the little hub, the 40-50 people using it day-in-day-out would make for some serious network congestion. Edit: Believe you me, I would 100% prefer to go with a traditional network setup. – Markus Aug 10 at 20:24
  • Running wires between the trailers will help a lot with the access to the file server. It's the difference between 15/5 Mbps and 1/1 Gbps for file server access. – Todd Wilcox Aug 10 at 20:29
  • Absolutely it would. My concern, however, is making sure that the one QNAP can make itself available on all ten networks. Even if we set the printing issue aside (and restrict them to per-trailer printing), I don't know how we could get the QNAP NAS available for all users. I mean, the simplest explanation would be to plug it into a switch and then run cable out to each trailer, but wouldn't it have some issues with the routing at that point? – Markus Aug 10 at 20:35
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    Re: "wouldn't it have some issues with the routing at that point?". Not if you design this correctly. Put the qnap nas on another subnet that all trailers have access to. – Mike Pennington Aug 11 at 1:11
up vote 3 down vote accepted

If you have access to 10 layer 3 switches you can certainly make this work. Treat each trailer as if it is a campus building with local internet. choose the trailer with the NAS as the core of the network and wire up each trailer to that core switch. Campus Design Wire each switch in the trailer to the LTE router and create a static default route to the specific LTE router for that trailer. I threw together a quick design to show that im talking about. Single Trailer Design I suggest configuring dynamic routing between the trailer switches and the core switch so that each trailer switch knows about the subnets at each other trailer. Otherwise you will have to configure static routing for each subnet on each switch which is a pain in the ass.

At the core switch i would just use the same VLAN for the Routed VLAN between each of the trailer switches to keep the configuration down.

Because most of the LAN traffic will be file sharing to the NAS it makes sense to connect each trailer directly to the trailer with the NAS as it reduces the number of hops needed to get to the NAS. Also if want to make the network resilient you can use two cables to connect each trailer to the core trailer and bond them together using LACP.

  • This is amazing; thank you for putting the time in to illustrate it more clearly. This was my original hope when I spoke to DLink, but 36 hours later their networking people haven't gotten back in touch. Thank you for confirming my suspicions, and I'll look into getting this sorted right away! – Markus Aug 11 at 14:01
  • The big thing you need to understand is that the switch having routing capabilities. Ideally you want to get switches that can participate in dynamic routing such as OSPF or in Cisco's case also EIGRP. If you company is willing to spend the money on 10 LTE routers, then they should be able to supply decent layer 3 switches. – Trevor Butler Aug 12 at 4:09

Two ideas...

I think the typical way to handle it would be a router in every trailer with three subnets: one goes to a switch for a trailer LAN, one goes to a campus backbone LAN for access to server, one goes to the LTE device for that trailer. A lot of work for ten tiny LANs but it wouldn't be so bad.

Simpler alternative - use both the wired and wireless ethernet on each computer. The wireless is for internet access - connects to the LTE device in the trailer. The wired is for access to the local resources, servers, printers, etc. The wired port will not have a default gateway. If you can get DHCP configured to deal with things correctly it should be very easy.

  • I would avoid option two; my experiences with M$ windows is that it doesn’t grok connectivity to multiple connected subnets reliably. By reliably I mean that hundreds of PCs could do that constantly without issue. – Mike Pennington Aug 11 at 11:15
  • @MikePennington - I am currently using that simple method in 13 locations across the country due to a software vendor's requirements. I thought it was kind of hokey and I guess I still do, but it has been completely reliable for five years - never a single issue with Windows figuring out how to communicate with the two networks. – batsplatsterson Aug 11 at 11:45
  • I had software that required it in roughly 450 Windows 2012 servers. Of those 13 periodically would have "network problems" talking to the default-less connected network. Reloading the Windows 2012 boxes always solved the "network problem" – Mike Pennington Aug 11 at 13:54

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