BGP
The Glue that holds the Internet together
BGP - The Glue that holds the Internet together
The Internet is often thought of in terms of fiber-optic cables, datacenters and servers. But behind the physical infrastructure lies a set of invisible rules and systems that make it all work. One of the most crucial of these is the Border Gateway Protocol, or BGP. It doesn’t get much attention outside of networking circles, but without it, the Internet as we know it simply wouldn’t exist.
Think of the Internet as a massive patchwork of thousands of smaller networks—each owned by different organisations, companies, and service providers. These networks are called Autonomous Systems (ASes), and each one needs a way to talk to the others.
BGP is what allows these different networks to exchange routing information. It’s essentially a set of rules that tells networks how to send data from point A to point B—even if that journey takes it through a dozen other networks along the way. Unlike routing protocols that work inside a single network, BGP operates between networks, making it the glue that holds the global Internet together.
How BGP Actually Works
The basic idea behind BGP is pretty straightforward, even if the technical details can get complex. When two networks form a direct BGP relationship—known as “peering”—they use BGP to announce which IP address ranges (or prefixes) they can reach. These announcements are like a map, showing what routes are available for data to travel.
From there, BGP uses a set of rules and attributes to decide which path is best. It doesn’t look at things like distance or speed, but routes traffic based on the policies, business agreements, and preferences set by the network. That means data isn’t always routed the shortest way, but often the most reliable or efficient way according to each network’s goals.
Why BGP Matters So Much
BGP’s importance becomes clear when you consider what it enables.
For starters, it makes the Internet resilient. If one connection fails—say, a cable is cut or a datacenter goes down—BGP can automatically reroute traffic through another available path.
BGP ensures all global IP traffic finds its destination. Every time you load a website or stream a video, BGP decides how your request gets to its destination. It’s working constantly to make sure your data takes the most optimal route.
But with that power comes risk.
One of the most well-known incidents occurred in 2008, when Pakistan Telecom unintentionally hijacked YouTube's IP prefixes. In an attempt to block access to YouTube domestically, they rerouted traffic away from the platform—only to mistakenly announce those routes to the entire Internet via BGP. The result? YouTube was unreachable globally for nearly two hours, as Internet traffic was misrouted to a blackhole in Pakistan. It was a dramatic demonstration of how a misconfigured BGP route in one country could disrupt services for millions worldwide.
Another major BGP-related incident took place in October 2021, when Facebook and its family of services—WhatsApp, Instagram, Messenger—went offline for over six hours. The root cause was an internal configuration error that effectively withdrew Facebook’s DNS routes from BGP, making it impossible for the Internet to find their servers. Users across the globe were met with connection errors for hours.
The Challenges That Come With BGP
The above two incidents perfectly describe one of the major challenges of BGP: complexity. BGP is powerful and flexible, but also easy to misconfigure. A single error in a routing policy can affect vast portions of the Internet. And when things do change—say, a route becomes unavailable—BGP can take longer than other protocols to adapt. This slow convergence can delay the recovery process during outages.
A second challenge is security. While the two incidents described were caused by accidental misconfigurations, BGP is also vulnerable to intentional, malicious actions. Designed in a more trusting era of the Internet, BGP lacks built-in safeguards, making it susceptible to both human error and exploitation. To address this, the industry is moving toward more secure and automated routing practices. Tools like RPKI (Resource Public Key Infrastructure) play a critical role in validating the origin of route announcements and reducing the risk of accidental mistakes. Complementing this, newer mechanisms such as ASPA (Autonomous System Provider Authorization) are being developed to enhance protection against route leaks and malicious intent—threats that RPKI alone does not fully address.
Looking Ahead: The Future of BGP
As the Internet continues to evolve, BGP must evolve with it. Strengthening its security through tools like RPKI and ASPA, adding more automation and security, and improving route validation are all crucial steps in making BGP more resilient.
At the same time, the demands on BGP are growing. The global routing table is nearing 1 million IPv4 routes as larger prefixes are increasingly split into smaller blocks. More networks are operating their own ASNs, and global expansion is driving the need for smarter route management. The ability to scale and adapt will be essential in keeping the Internet stable and efficient in the years to come.
Final Thoughts
It’s easy to take the Internet for granted. We send messages, stream content, and access information without thinking about how that data gets from one place to another. But behind the scenes, BGP is doing the heavy lifting—quietly, efficiently, and almost invisibly.
While far from perfect, BGP remains one of the most important protocols on the Internet. It not only connects millions of networks, but also keeps them running smoothly, securely, and reliably. And even if you’ve never heard of it before today, you rely on BGP every time you go online.
