A handful of caching edges in front of one origin covers most of what a commercial CDN does for a European audience, at a fraction of the per-terabyte price. The architecture, the nginx configuration that does most of the work, how users reach the nearest edge, and where the do-it-yourself version loses.
The port is the easy part — it is lit in an afternoon. Then the machine behind it has to produce 12.5 gigabytes every second, and each layer between the disk and the wire gets a chance to be the reason it does not. The arithmetic, in the order it fails.
Both protocols get video from an encoder into your origin; neither is what viewers receive. Judged on that one job, they differ sharply under packet loss — and the SRT latency setting decides whether it helps at all. A comparison, with the pipeline around it.
Kernel settings are changeable; the distance between your server and your users is physics. Work out the latency floor from the map, understand why interconnection decides how close you get to it, and test from where the users actually are before committing.
One exit node is easy to specify and tells you nothing about the next fifty. Concurrency, throughput per session and oversubscription set subscribers per node; packet rate rather than cipher choice sets the ceiling; and country coverage wants a tiered fleet, not identical boxes.
Monthly transfer is the wrong starting point, because a port is a rate. Size from peak concurrency, per-unit bitrate and headroom — then check the cost per gigabit of each tier, because that curve is not monotonic and the cheapest gigabit is not where most people buy.
The BGP session is the easy step. What decides whether your route reaches anyone is the LOA, the IRR objects, and a ROA whose max length is not quietly authorising somebody else to originate your more-specifics.
The machine is the easy part. Address reputation, geolocation and an abuse process that answers decide whether the service works at all — then conntrack, MSS clamping and IPv6 decide whether it scales past one node.
Transit buys reach to everywhere by the longest road. Peering buys a short path to the networks you actually send to. What each one costs, how BGP picks, and how to read the difference from your own shell.