How One Bad Packet Can Take Down the Internet: Welcome to BGP

When you type “google.com” and hit enter, your computer doesn’t just talk to Google. It launches a journey through a chaotic web of networks—thousands of them, run by different companies, countries, and competitors. Somehow, your data weaves through all of them and ends up exactly where it’s supposed to.

How?

The short answer is a protocol called BGP—Border Gateway Protocol. It’s the system that tells all these independent networks how to find each other. But calling BGP a “routing protocol” is like calling diplomacy just “talking.” It’s not just technical. It’s political, fragile, and surprisingly old.

Where BGP Came From (and Why That Matters)

Back in the early days of the Internet—when it was basically just a U.S. research network—routing was easy. The whole thing was small, centralized, and trusted. The protocol at the time, EGP (Exterior Gateway Protocol), assumed that one central backbone would manage traffic for everyone else. It was top-down, like a tree. That made sense when the only people online were universities and government labs.

Then the Internet exploded.

Commercial ISPs came online. So did global telecoms, universities from around the world, private networks, military infrastructure—each with their own priorities. Suddenly, that neat hierarchy collapsed. Nobody wanted to be told how to route traffic. They wanted control.

So in 1989, two engineers—Kirk Lougheed from Cisco and Yakov Rekhter from IBM—scribbled down a new idea at an IETF meeting on napkin. That sketch became BGP. Instead of assuming trust or central control, BGP let each network decide for itself what routes to share, what routes to accept, and how to reach the rest of the Internet.

In 1989, at an IETF meeting, two engineers—Kirk Lougheed (Cisco) and Yakov Rekhter (IBM)—sketched a new idea on a napkin. That sketch became BGP.

Unlike its predecessors, BGP didn’t assume central control or mutual trust. Instead, it handed autonomy to each network: decide what to share, what to accept, and how to reach the rest of the internet—on your own terms.

It wasn’t built for harmony. It was built for distrust—and that’s exactly why it worked. Below is the original BGP protocol sketched at an IETF meeting, 1989.

BGP Doesn’t Find the Best Path—It Finds an Acceptable One

Most people assume that the Internet is optimized. That your traffic always takes the shortest or fastest route. That’s not how BGP works.

Where traditional routing protocols like OSPF or RIP focus on efficiency—metrics like hop count, link speed, or latency—BGP is all about policy. ISPs and network operators use it to make routing decisions based on business deals, geopolitical constraints, or technical limitations. They might avoid a perfectly good path because it goes through a rival network. Or prefer a longer path because it’s cheaper.

This flexibility is why BGP became the backbone of the Internet. But it also means that routing decisions aren’t always rational—or even safe.

Key Insight: BGP doesn’t care about the “best” route. It cares about what networks are willing to accept.

That trade-off—flexibility over optimization—is why your traffic might go through five countries to reach a server across the street. It’s also why a mistake by one small ISP can knock YouTube offline for half the world.

How BGP Picks a Path (and Why It’s Not the One You Expect)

Let’s say your packet wants to get from Mumbai to London. There are a dozen possible routes it could take—some fast, some slow, some cheap, some political. So how does the Internet decide?

It doesn’t. BGP does.

But BGP doesn’t look for the shortest route. It doesn’t test for latency, bandwidth, or even congestion. Instead, it runs a path-selection process based on what networks want to happen. That’s because BGP isn’t just a routing protocol—it’s a policy engine disguised as infrastructure.

What BGP Really Does: Think Diplomacy, Not Math

BGP is what’s called a path-vector protocol. That means every route announcement includes a complete list of which networks (Autonomous Systems, or ASes) the traffic will pass through. This list is called the AS-PATH, and it's central to how BGP prevents routing loops and evaluates options.

Each BGP router builds a table of all the known paths to every reachable IP prefix—and then it runs a strict decision algorithm to pick just one "best" path. But “best” in BGP doesn’t mean “fastest” or “shortest.” It means most acceptable under the local network’s policies.

Here’s how the decision process works, in order:

1. Local Preference: Set manually by the network operator. This overrides everything. If your ISP decides traffic to Google should go through France, that’s what happens.
2. AS-PATH Length: Fewer AS hops are better—if Local Preference doesn’t override it.
3. Origin Type: Prefer routes originated via IGP (interior) over those redistributed from EGP.
4. MED (Multi-Exit Discriminator): If two routes come from the same neighbor, pick the one that prefers a specific link.
5. eBGP Over iBGP: External BGP routes are considered more trustworthy than internal ones.
6. Router ID: A final tie-breaker based on the unique ID of the advertising router.

At a glance, it feels like a cascade of technical preferences. But step back, and it’s clear: the entire system is rigged for policy control. The real authority sits at the top—Local Preference—a setting that network operators configure explicitly to enforce their business, legal, or geopolitical goals.

Why Local Preference Comes First (And What That Means for You)

This is where BGP reveals its real nature. Performance? Efficiency? Not the priority. Instead, the protocol empowers every AS to shape routing based on who pays whom, who trusts whom, and who can’t legally send data where.

Let’s break that down:

• Peering vs. Transit: A network might route traffic through a slower peering connection to avoid paying for transit. Even if the performance is worse, the cost savings win.

• Regulatory Compliance: In countries with data sovereignty laws, ISPs are required to keep domestic traffic within national borders—even if the shortest path is international. So your data might take a detour just to stay legal.

• Political Tensions: Some ASes intentionally avoid routes that pass through rivals or untrusted regions. If two countries are in conflict, their ISPs might refuse to peer directly, forcing traffic onto inefficient paths.

And that’s not a bug. It’s how the protocol was designed to work. The idea was never to build a fast or elegant Internet—it was to let thousands of networks cooperate without giving up control.

The Real-World Consequence: Strange Routes, Slow Latency, and Zero Transparency

If you’ve ever wondered why your request to a nearby server takes a bizarre, international route before looping back—it’s probably BGP. The router didn’t pick the shortest option. It picked the one that matched business rules.

And there’s no easy way to tell. BGP decisions are made behind closed doors, based on settings most users never see and deals that aren’t public. So while your browser waits, your data might be visiting Frankfurt, because someone somewhere prefers it that way.

BGP’s Fatal Flaw: It Assumes Trust (And That’s a Problem)

BGP, for all its complexity, runs on a shockingly simple assumption: every network is honest. That’s it. There’s no built-in authentication, no cryptographic checks, no enforcement. If a network claims to own an IP block, BGP believes it. If it says “send traffic here,” the rest of the Internet shrugs and obeys.

This isn’t a design oversight—it’s how the protocol was built. In 1989, the architects of BGP weren’t trying to defend against adversarial states or profit-driven hijackers. They were trying to get Stanford, MIT, and the NSF backbone to talk to each other. Trust wasn’t just assumed—it was baked into the system.

That trust still runs the global internet today. And sometimes, it breaks. Badly.

The YouTube Blackhole: When a Country Took Down a Global Platform

In 2008, Pakistan’s telecom regulator ordered ISPs to block YouTube nationwide. Instead of filtering it at the DNS level or using a firewall, Pakistan Telecom took a more blunt approach: it announced a more specific BGP route to YouTube’s IP range, pointing the traffic to a null destination. A kind of digital sinkhole.

Locally, this worked. Users in Pakistan trying to access YouTube got nothing. But here’s the catch: the route didn’t stay local.

Due to a misconfiguration—or perhaps simply a failure to filter outbound announcements—the fake route propagated to Pakistan Telecom’s upstream provider. From there, it spread to the global internet.

And because BGP always prefers more specific routes (a /24 beats a /16), the forged announcement from Pakistan overrode YouTube’s legitimate one. For hours, much of the world’s YouTube traffic was rerouted into a black hole.

There was no malicious hack. No zero-day exploit. Just a misstep—and a protocol that trusted what it shouldn’t.

Why This Keeps Happening

The YouTube hijack wasn’t a one-off glitch. BGP route leaks and hijacks are frequent, often accidental, and occasionally exploited for strategic or economic gain.

Here’s why these failures are baked into the system:

• No Authentication: BGP has no native way to check whether an AS actually owns or is authorized to announce a given IP prefix. It just takes the announcement at face value.

• Specificity Bias: BGP always prefers the most specific prefix. That makes /24 hijacks easy and dangerous. Even if a legitimate network announces a /16, a rogue /24 will win.

• Global Scope: A single bad announcement can propagate worldwide in seconds. And unless someone’s watching—and has the power to filter—it won’t stop.

A Pattern of High-Stakes Failures

Here’s how that trust model has repeatedly collapsed:

Notice the variety here: not all were malicious. Some were misconfigurations. But the outcome is the same—global disruption triggered by a local decision.

Trust Without Verification Is Fragile

The internet, despite its reputation for being robust and decentralized, hinges on a protocol that has no way to verify claims. And while proposals like RPKI (Resource Public Key Infrastructure) aim to fix this, adoption remains incomplete. Many networks still run wide open—able to be spoofed, hijacked, or leaked.

So when someone asks, “How can one small ISP cause a global outage?” the real answer is: because BGP lets them.

Why BGP Is So Hard to Fix: Securing a Protocol That Assumes Trust

BGP’s security flaws aren’t news. Engineers have known for decades that any network can claim any IP prefix, and most of the internet will accept it. The real question is: why hasn’t this been fixed?

The Fixes Exist—They Just Don’t Scale

• RPKI cryptographically verifies route ownership. But adoption is low (~40%) and misconfigurations can cause valid routes to be dropped. Few networks want to risk breaking reachability.

• BGPsec validates every hop in the AS path using cryptographic signatures. It solves path spoofing—but is too heavy to deploy at internet scale. Routers aren’t built for it, and nobody wants the overhead.

• Manual filtering (ISPs hand-picking acceptable routes) is still common. But it’s tedious, error-prone, and doesn’t scale to 70,000+ networks.

Why This Isn’t Fixed Already

BGP has no central authority. Unlike HTTPS—where browsers enforce standards—no one can compel ISPs to secure their routing. The incentives are misaligned: the benefits of securing BGP are global, but the costs are local. Most networks don’t see a direct return on securing routes for others.

Worse, new defenses carry risk. Misconfigured RPKI can cause legitimate outages. So many networks choose reliability over security. It’s a rational response to a fragile system.

Beyond Tech: BGP Is Political

Routing isn’t just technical—it’s geopolitical. Countries like China and Russia use BGP to enforce domestic control, routing traffic through national infrastructure. Meanwhile, big content providers bypass traditional ISPs using private interconnects, reshaping who controls traffic flow.

Built-In Trade-Off: Stability Over Speed

BGP is slow to converge by design. That’s what keeps the internet stable—but it also means hijacks and outages can persist for minutes or hours. It resists change for the same reason it resists collapse: conservatism is a survival strategy.

BGP’s problems aren’t a secret. They’re just embedded in the architecture, incentives, and power structures that define the internet.

Final Thoughts: The Internet Runs on Trust, Not Design

BGP wasn’t built for scale or security—it was built for trust. And that trust is wearing thin.

Its flaws are obvious: no authentication, policy over performance, and fragile convergence. But that’s also what makes it work. Not because it’s well-designed, but because every player has just enough incentive not to break it.

The next time your traffic takes a weird route, remember: it’s not a bug. It’s BGP doing what it was never meant to do—and somehow still holding the internet together.

---

Like this BGP deep dive? ☕ Fuel more tech rants

Warning: May induce involuntary networking lectures at family dinners.

(Peering agreement optional)