If you are going to bury fiber, the minimum I would put in is 4 strands. Even more stands if possible 8-12 would be better. If you put in conduit, leave a pull string in place to pull more fiber in the future if needed. Remember, you need one fiber per direction. And yes I know you can get special SFPs for bidirectional transmission, but why limit yourself to the extra cost and reduced selection by going this way.
As far as fiber type, you would probably be better off with multi-mode as it will go the distances you want and should be a little cheaper. Single mode could go a greater distance, plus you can run higher speed optics over it a greater distance. If you thought you may ever want to run 10Ge sppeds across this network, I would put in the SM fiber day one. You may have to find someone local to splice the connectors on to the fiber. Alternativly, you could get the fiber already conectorized and just direct bury vs try and pulling it through conduit.
Get a pair of Ge switches that support SFPs and you should be good to go. You may as well light a second pair and enable LAG across them if the switch supports two SFPS which a lot of them will. It would be a cheap investment for the extra reliability. The extra capacity is just a side benefit. Another advantage of the switches is that you could setup VLANs to keep the customer and owner traffic/networks seperate.
A generic SFP can be found for ~$60-$70 at a lot of locations.
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www.provantage.com/addon ··· N0V7.htmAlternatily, you could get a couple of these media converters, »
www.provantage.com/tp-li ··· K00N.htm, and a SFP for it »
www.provantage.com/tp-li ··· K02W.htm an use cheap unmanged switches on each end. A these prices, I would probably buy one or two of each as a spare as they would have to work in pairs. I have no clue as to the quality of any of these parts.
Before I would purchase the fiber from ebay, I would go to a US supplier an make sure you have everything worked out as far as connector and and fiber type/size before you place any orders. I grabbed this site as an example from a Google search. I don't know anything about them nor am I recomending them.
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fiberopticcables.stores. ··· uca.htmlMe personaly, I would just buy an 8 strand pre-conectorized armored SM direct burial cable of the appropriate lenght and hire someone to trench a 48" deep route, drop the cable in it, ground the cable, verify it works and cover the cable.