Internet Service Provider (ISP)

An Internet Service Provider (ISP) is a commercial entity that offers internet access to end-users. ISPs play a crucial role in connecting users to the vast network of the internet. They provide the necessary infrastructure and services to enable individuals and businesses to access and utilize the internet for various purposes.

ISPs can be classified into different tiers based on their resources and capabilities. Tier 1 ISPs have abundant resources and infrastructure, allowing them to operate at the top of the hierarchy. They do not have to pay for internet traffic as they have direct peering relationships with other tier 1 ISPs. Tier 2 ISPs, on the other hand, need to make settlements through transit agreements with tier 1 carriers to access the internet. Tier 3 ISPs act as last-mile providers, delivering internet services to end-users without investing in significant infrastructure. They establish transit agreements with tier 2 ISPs to ensure connectivity.

Since the inception of the internet, ISPs have been an integral part of its growth and development. They offer a wide range of services, including access, hosting, and information services. Some ISPs specialize in specific services, while others provide a combination of access, hosting, and information services based on the needs of their customers.

Access services allow users to connect to the internet and browse websites, access email services, and perform various online activities. Hosting services involve providing server space and resources for individuals and businesses to host their websites and online applications. Information services include storing and retrieving data files like images, videos, and other content on websites.

What is the internal hierarchy of ISPs?

The internet is a complex network made up of multiple interconnected smaller networks, known as autonomous systems (AS). Each AS operates as a standalone unit with its own routing policies. Autonomous systems consist of various devices, including routing and switching devices for internal communication and end nodes for data transmission. To track the movement of data packets, each device is assigned an IP address.

IP addresses are divided into public and private IPs due to the large number of devices on the internet. Private IPs are used within organizations to manage their internal Local Area Networks (LAN). Communication within an AS is facilitated by interior gateway protocols (IGPs), while exterior gateway protocols (EGPs) are used for outbound communications that exit the autonomous system.

Initially, ISPs owned a single autonomous system. However, to ensure efficient connectivity and redundancy, ISPs now maintain multiple autonomous systems by establishing points of presence (PoPs) at various locations. These PoPs act as local hubs for network traffic and enable ISPs to serve their customers more effectively.

What is the process of data traveling through ISPs?

To understand how ISPs facilitate internet access for end-users, let’s consider an example. When users want to access a website like CoinMarketCap, they enter the website’s URL in their browser or use a dedicated app. The request travels from the user’s device to the local network routers, typically installed by a tier 3 ISP.

These routers assign source IP addresses to the request and have route tables that determine the path for the data packets. Based on destination IP addresses, the routers either directly route the request to the server hosting the website or send the packet to DNS servers maintained by the ISP. The DNS servers retrieve the stored cache and return the IP address at which the website’s servers are hosted.

Once the IP address is obtained, the request is sent to the appropriate server, and the requested webpage is delivered back to the user’s device through the same path. This entire process happens in a matter of milliseconds, allowing users to access websites and online services seamlessly.

What are ISPs as Rule Enforcing Agents?

ISPs are not just responsible for providing internet access; they also play a crucial role in enforcing rules and policies to ensure a safe and secure internet environment. ISPs have a set of rules that customers must follow, including restrictions on accessing certain websites with unlawful content.

To enforce these policies, ISPs employ techniques like deep packet inspection (DPI), where they scan every website visit against government databases and predefined rules. DPI allows ISPs to identify and block websites with prohibited content, protecting users from potential threats and ensuring compliance with legal requirements.

By acting as rule enforcing agents, ISPs contribute to maintaining a reliable and secure internet infrastructure for all users. They play a vital role in preventing cybercrime, protecting user privacy, and promoting responsible internet usage.

In conclusion, ISPs are commercial entities that provide internet access to end-users. They enable individuals and businesses to connect to the internet and access various services like browsing the web, hosting websites, and storing data files. ISPs operate within an internal hierarchy based on their resources and capabilities. They facilitate the movement of data packets through their networks to ensure seamless connectivity. Additionally, ISPs enforce rules and policies to promote a secure and trustworthy internet environment. As the internet continues to evolve, ISPs will play a critical role in shaping its future and enabling global connectivity.