I came across Brian’s comment on Backblaze reddit, where I learned of a few interesting things about how internet data traffic is billed between customers, hosts and transit partners. In particular, they explain how Backblaze and Cloudflare have peering agreements in place to enable free egress for customers. It’s great read!
The way the CloudFlare/Backblaze relationship works is that CloudFlare is very arguably big enough to be tier 1, and should be allowed to have the utterly free peering of a tier 1 provider, but they are “locked out”. They don’t get the sweet sweet deal the tier 1 providers get of running their businesses terribly and pocketing billions of dollars of profit without innovating. So normally, without contortions, if a Backblaze customer wanted to route a network packet to CloudFlare, it would flow over at least 1 of the tier 1 network providers and Backblaze and CloudFlare would both have to pay a lot of money. But here is the work-around: Backblaze is in several datacenters where CloudFlare has network cabinets (where their equipment is housed), and essentially CloudFlare and Backblaze run a network patch cable between our cabinets BYPASSING the tier 1 network, and therefore don’t have to pay the tier 1 providers to route packets between Backblaze and CloudFlare. That’s it, that’s the magic.