How is the IR blocking the internet?
All* internet traffic between data centers and countries is routed over a protocol called BGP(Border Gateway Protocol). Each "hub" inside the global BGP-network is known as an Autonoumus System (AS), from each AS a number of IP-address blocks are announced to let the outside world understand where a particular IP-address resides in the global network; essentially saying: "These addresses live here, send their traffic to us. In practice, an AS is simply a network run by a single organization, an internet provider, a university, or a large company. Iran's internet architecture is designed with a "hub and spoke" pattern. Think of it as a wheel, the spokes are Iran's national internet service providers (ISPs), and the hub is the regime-controlled gateway. All the ISPs (the spokes) must route their traffic through that central hub to reach the outside world. There is no back door, no alternative route out. This was not an accident it was a deliberate architectural choice. If you control the traffic flow inside the hub, you can somewhat easily shut down and filter the internet. In practice, this means the regime can flip a switch and the entire country goes dark; not because thousands of individual networks were shut down one by one, but because one choke-point was closed. It is the digital equivalent of a country having only one international airport. Nerd stuff: *BGP is the dominant inter-domain routing protocol (between different AS/networks/countries), but traffic within a single network could use other internal routing protocols. Observe the connectivity table here: https://radar.cloudflare.com/routing/as49666 You'll see a list of AS-numbers, the type of peering, country of origin, name and such. Type "Down" means this is a downstream i.e. AS49666 is the upstream transit provider between all peers considered as down, meaning if they want to communicate with any other AS they have to transit through either one of their upstream ASes.