Backbones and Network Access Points

1) Backbones:
In the context of the internet, backbones refer to the primary routes or high-capacity data transmission pathways that form the core of the internet's global infrastructure. These backbones are typically composed of fiber-optic cables, high-speed routers, and other advanced networking equipment that facilitate the transfer of large volumes of data across long distances, often between major cities and continents.
Purpose:

• Data Transmission: Backbones serve as the main conduits for internet traffic, allowing data to travel quickly and efficiently across the network.
• Global Connectivity: They connect different regions and countries, enabling the global reach of the internet by linking regional networks and Internet Service Providers (ISPs).
• Redundancy and Reliability: Backbones are often designed with redundancy in mind, meaning there are multiple pathways for data to travel. This redundancy ensures that if one path fails, data can be rerouted through another, maintaining the reliability and uptime of internet services.

2) Network Access Points (NAPs):
Network Access Points (NAPs) are critical facilities where different networks, including ISPs and backbone providers, connect and exchange data. NAPs are a type of internet exchange point (IXP), but they are historically significant as they were among the first large-scale IXPs established in the early days of the commercial internet.
Purpose:

• Interconnection: NAPs facilitate the physical and logical interconnection of different networks, allowing them to exchange internet traffic. This interconnection is essential for the decentralized nature of the internet, as it enables data to move seamlessly between different networks.
• Traffic Exchange: At a NAP, internet traffic from one network can be handed off to another. For example, when you visit a website, the data may pass through several networks interconnected at NAPs before reaching your device.
• Performance Optimization: By providing a centralized location for networks to connect, NAPs help to reduce the number of hops data must take between its source and destination, which can improve speed and reduce latency.
• Cost Efficiency: NAPs allow networks to directly exchange traffic with each other without the need to route through a third-party network, which can reduce costs associated with data transfer.

In summary, backbones form the high-speed core of the internet, while Network Access Points are critical junctions where these backbone networks and other smaller networks meet and exchange data, ensuring the smooth and efficient operation of the global internet.

If you request a Web page, that information often has to cross several networks before it gets to you. Those networks that it crosses are called backbones. Without backbones it would be nearly impossible for you to receive the information you asked for. The Internet backbone comprises very high-bandwidth lines interconnected with fast, high-capacity routers. In brief, backbones are high-speed networks that carry Internet traffic. Commercial backbone providers include PSINet, UUNET, ANS/AOL, Sprint, AT&T, GTE, IBM, and MCI. In the image below you will notice that major ISPs and smaller networks are connected directly to a backbone ISP. The backbone ISPs are unique in that they carry high-speed connections between them and are ultimately responsible for transporting information over the network. National long-distance carriers or the government generally install backbone lines.
A backbone ISP, also known as a Tier 1 provider^[1], is theinternet's equivalent of a highway system. Just like highways connect cities and towns, backbone ISPs connect major networks and data centers around the world, forming the core infrastructure that carries the massive amount of data traffic we generate every day. Imagine the internet as a massive web, with individual users and smaller ISPs being the local roads and smaller towns. Tier 1 ISPs are the high-speed highways that connect these smaller networks, allowing data to flow smoothly and efficiently across vast distances. Here are some key characteristics of backbone ISPs:

• Global reach: They have extensive networks spanning multiple continents, with connections to major internet exchange points (IXPs) around the world.
• High bandwidth: They can handle enormous amounts of data traffic, often exceeding 100 Gbps or even 1 Tbps.
• Redundancy: They have multiple backup paths for data to travel in case of outages or congestion, ensuring high availability and reliability.
• Peering agreements: They exchange traffic with other Tier 1 providers through peering agreements, which allows for efficient data exchange without incurring charges.
• Limited customer base: Unlike your local ISP, Tier 1 providers typically don't directly serve individual users. They primarily sell their services to other ISPs, content providers, and large enterprises.

Here's an image to help visualize the role of backbone ISPs in the internet ecosystem:

As you can see, Tier 1 ISPs sit at the top of the hierarchy, forming the backbone of the internet. Tier 2 ISPs connect to Tier 1s and then provide services to smaller regional ISPs (Tier 3) who, in turn, serve individual users and businesses. Backbone ISPs play a critical role in ensuring the smooth functioning of the internet. They are responsible for carrying the vast majority of the world's internet traffic, and their performance and reliability directly impact our online experience.

Backbones join at network access points (NAPs). As the name implies, network access points are the entryways to the Internet. For example, think of all the people from around the world who come to San Francisco to cross the Golden Gate Bridge. They all meet up at the toll plaza before crossing. The toll plaza is equivalent to the network access point. It's a universal gateway. Network access points tie various ISPs and the national telecommunications companies. NAP examples include Sprint and Worldcom. They provide routing flexibility, bandwidth savings, and permit reduction of network lengths. Here are examples of both public and private NAPs.

In the next lesson, the specific hardware and software network connection devices will be discussed.

[1] Tier1 Provider: A Tier 1 provider is an internet service provider (ISP) that operates at the highest level of the internet hierarchy. They own and manage extensive global network infrastructure and can reach any other network on the internet without purchasing transit or paying for peering arrangements.