What does an Internet Service Provider (ISP) network look like?

One can envision a country's internet network as a system of tree roots. The central roots are thicker and as we move away from the center, the roots become more distributed and thinner. In this analogy, the central points are where large Internet Service Providers (ISPs) establish international connections. In a medium-sized country, only a few ISPs may have these international connections, meaning all the country's network traffic must pass through a limited number of routers to leave the country.

Smaller ISPs would connect to these larger ones to direct traffic internationally, most likely via an Internet Exchange Point (IXP). These connection points form what is known as the Core Network, which in a small to medium country, would likely be located in a single city.

SPs extend their Access Network to provide internet services to their customer base across the regions they cover, which could be an entire country or specific provinces/states. The Access Network is where ISPs install their cell towers to deliver 3G/4G/5G services to mobile phone users. For fixed broadband end users, connection to the Access Network is facilitated through Points of Presence (PoPs).

Illustration of ISP Network Design