I have a customer who wants me to design a solution for a wireless WAN they are building. They are installing wireless equipment on top of approx. 30 radio towers with either FastEthernet or some sort of fiber handoff down to "huts" at the base of the towers. The WAN will span approx 150 miles and will form a ring. In the future other people (ISPs, companies, schools, etc.) will want to build to these towers and connect to the network. I'm going to assume a FE handoff for this design. This "interconnect" traffic will be considered "public". I am tasked with placing switches/routers in each hut to accomodate this network.
1. Minimum 200 MB between WAN sites
3. Ability to segment public/private traffic
Now I am considering a two switch configuration at each site. Something like two 3560-24TS switches which will cover redundancy and some flexibility with the SFPs ports. And it should have plenty of capacity with only 200 MB of site to site BW. I don't expect more than a handful of interconnects at the towers so the port count should be fine.
My concern is that I've never created a layer two network over a WAN. Is this recommended? Does spanning tree have issues at these distances? Or should I be giving each site it's own subnet and route traffic? If that's the case should I be looking at routers instead of L3 switches?