The most important aspect of engineering any network is your backhaul capacity planning – that being how many customers your network can sustain at an acceptable (or ideally exceptional) rate of speed. This article will cover the two types of backhaul capacity you will need to plan for when building out your network:
First it’s important to know the variety of wholesale internet connections that you can potentially source for your network – this includes everything from fiber, to fixed wireless, to (potentially) satellite backhaul connections.
Fiber
Most commonly (or perhaps ideally) you should look to source your primary DIA connection from a fiber provider – e.g. CentruyLink Wholesale / Lumens, Layer 3, Hurricane Electric, Verizon, AT&T, etc. A wired fiber connection has the advantage of typically being the cheapest, fastest, most stable, and easiest to upgrade type of connection. There are a wide array of fiber carriers in the US, from major corporate fiber carriers, to regional, or even local fiber carriers. A standard, base-line, 500mb/s fiber circuit will typically cost around $1000/month, commonly with a multi-year contract, however the price for additional bandwidth usually gets much cheaper the more bandwidth you buy (i.e. 1gig @ $1500/month, 1.5gig for $1800, etc.). While most fiber carriers are relatively equal to one another, it’s important to research all your options in the area, and do your due diligence in both negotiating price and researching their uptime and SLA agreements.
However, particularly when deploying rural broadband networks, the availability of a fiber line can be difficult, if not impossible to source. In which case you’ll have to explore other options…
Fixed Wireless
Wholesale fixed wireless (i.e. point-to-point microwave connection) providers are typically more state or local ISP / bandwidth broker companies, rather than national carriers. Connections like these can sometimes be found from some of the relatively “larger” wireless ISP’s in a given state or locality, where they are willing to provide you with a fast wholesale connection from one of their towers in the area. This makes these types of connections both more flexible for deployment, and sometimes easier to negotiate a price, speed, and length of contract (potentially forgoing a contract entirely). Many fixed wireless providers will sell bandwidth at a set $/mbs ratio (e.g. with general inquiries I have been quoted at $3/mbs to start, lowering to $2/mbs over 1.5gbs), only going cheaper if you purchase a larger amounts of bandwidth or have a good working relationship with them. Usually with these types of connections there is a larger upfront cost (anywhere from $3000-$5000+) for equipment and tower crew installation. These connections can be fairly reliable, however you have to take into account there is added infrastructure involved that can fail, so the same stability as fiber is not always assured.
Satellite
When deploying where not even a fixed wireless carrier can reach there is the potential option of satellite. However, at the moment, the up-and-coming Musk venture “Starlink” is the only possible option as other satellite providers suffer from extremely high latency, and high cost, which rules them out for providing any form of quality modern broadband connection. For now, the potential for a viable wholesale Starlink connection remains a yet-to-be-determined solution.
Capacity planning for a DIA connection is somewhat of a continually moving target, being a combination of loose math and guess-work, as demand for bandwidth grows with each passing year (or month). To understand why this is you can read many long and hotly debated conversations such as this reddit thread. Referencing wikipedia on common ISP overselling practices you’ll find capacity planning numbers like this:
In a cable network utilizing DOCSIS 1.1, for example, the full 38 Mbit/s download bandwidth is typically shared by some 500 subscribers, each of which may be allocated 7 Mbit/s. [...] the download oversubscription ratio is 92:1.G-PON and XG-PON access networks are typically oversubscribed, with typical load-factors of approaching 256:1, due its point-to-multipoint architecture.