Internet Service Providers (ISPs) are commercial entities that provide end-users with access to the internet.
What Is an Internet Service Provider (ISP)?
Internet Service Providers (ISPs) are commercial entities that provide end-users with access to the internet. ISPs can be either tier 1, 2, or 3, based on the physical resources available for them to be used free of cost. This is known as peering/transit value differential (PVD).
Tier one has enough space and usually doesn’t have to pay any cost for the internet traffic as they exist at the top of the hierarchy. However, tier 2 must pay the settlement – usually through transit agreements with tier 1 carriers. And tier 3 ISPs act as the last-mile providers. They have transit agreements with a tier 2 ISP, and without investing in infrastructure, they provide internet services to commercial and home consumers.
What Is the Internal Hierarchy of ISPs
Initially, each ISP could own a single autonomous system, but now each ISP must maintain scores of AS efficiently by building a point of presence at several locations.
How Sending Data Through ISPs Work
To understand the full extent of how ISPs facilitate the end-users while they access the internet, let’s take a practical example. If users have to access CoinMarketCap, they will enter the URL in the browser or access it through the app. The request will travel from their devices to the connected local network routers, usually installed by a tier 3 ISP, where the source IPs are assigned. The routers have route tables and based on destination IPs, either they will directly route the request to the server where CoinMarketCap is being hosted. However, if they don’t have the routing table of the IPs stored, they will send the packet to DNS servers that the ISPs dedicatedly maintain and will get the stored cache from it and return it with the IP at which servers of CoinMarketCap are being hosted.
ISPs as Rule Enforcing Agents
ISPs are in charge of traffic shaping, route optimization, and other related tasks. They come with a list of rules that need to be followed when providing services for each customer, like preventing people from accessing certain websites due to unlawful content. They enforce these policies through deep packet inspection, which means that every website visit will be scanned against government databases. They are the backbone of a secure internet.