Our current internet architecture was conceived for the 1980s. It's time for an upgrade

• BGP, the main protocol governing the internet, was designed over 30 years ago, and is now not fit for purpose.

• SCION internet architecture provides a mature, stable alternative.

• SCION uses 'formal verification' to ensure stability and eliminates circular dependencies that make BGP problematic.

The COVID-19 pandemic has exposed and increased society's reliance on digital communication. To support the skyrocketing use of video calls, global networks have been rapidly expanded – internet bandwidth increased by 35% in 2020. Communication applications such as Whatsapp or Zoom are constantly being upgraded and strengthened to provide more efficient and secure services across the internet.

While these efforts are certainly helpful in ensuring a seamless internet experience, a core threat to internet availability still remains hidden, buried deep inside the digital machinery.

The Border Gateway Protocol (BGP) enables coordination between the over 70,000 different networks that interconnect into the single global communication infrastructure that we call the internet. As it turns out, BGP is one of the most fragile parts of the internet. While most of the hundreds of weekly outages caused by BGP's malfunctioning go mostly unnoticed, as they typically affect only a small fraction of users, extended disruptions are not uncommon.

In 2020, for example, one major incident affecting US service provider Cloudflare lasted for seven hours and caused a 3.5% drop in global traffic. This event, caused by a trivial misconfiguration, illustrates how minor hiccups in regional routers can trigger the proverbial butterfly effect that results in disrupting connectivity in large portions of the internet. Such outages result in enormous costs for businesses and disproportionally affect institutions that rely on the internet for critical services.

Given the crucial nature of the internet, an important question is: How did we get to rely on such an unreliable infrastructure? The answer is surprisingly simple: BGP was not designed to handle the global scale and number of interconnected networks that we have today. Famously dubbed the "two-napkin protocol" (as it was invented in a cafeteria during breaktime), BGP was created to support the interconnection of the much smaller internet of the late 1980s. Its mostly functional operation over the past 30 years has given a false sense of stability. To achieve a strong guarantee of reliable communication, we need stronger properties than those BGP can provide.

At ETH Zurich, we have been working on a modern replacement to the ageing BGP. The next generation SCION Internet is designed to be provably stable in the face of major disruptions and even hackers. By “provably” we mean that our researchers, aided by state-of-the-art software, applied “formal verification” to devise mathematical proofs of SCION’s stability. With formal verification, it is possible to reason mathematically about complex interactive protocols, and to prove statements about their outcome. This task is impossible with BGP, as it was built in a way that cannot guarantee stability in general.

No previous research project has applied formal verification to an entire internet architecture, but we did not stop there. We further use code verification to prove that SCION’s routers are correctly programmed to execute the protocol. While these two tools, protocol and code verification, have been used separately in the past, they have never before been combined for such a complex system.

It is estimated that the digital economy represented between 4.5% and 15.5% of world GDP in 2019, and has further grown since then. Further, a recent attack on a major ISP in Belgium shows how reliant many government entities are on internet communication.

Like other key infrastructure and utilities, the internet should be operated and safeguarded with enormous care. Power networks, for instance, are carefully protected against failures with elaborate contingency plans. In that sector, a crucial part in this process is dependency analysis, which highlights circular dependencies that can prevent the resumption of service after a blackout. Most importantly, the power network has to be able to “black-start”, i.e. recover from a complete shutdown – despite the fact that, paradoxically, many plants themselves consume electricity to produce electricity and thus require an external power source to start.

The internet should have a similar feature: After the disconnection of a large portion of the network, the re-establishment of connectivity should take seconds, at most. With BGP, unfortunately, circular dependencies are created by the very security extensions designed to protect participating networks from outside interference: They require internet connectivity to achieve secure internet connectivity! Such dependencies further slow down recovery from the outages described above.

Our analysis of the interdependency of SCION components showed that providing full connectivity of the whole internet can happen within seconds from a black-start. Starting only from local cryptography-based roots of trust, the networks participating in the SCION protocol can discover and authenticate communication paths to quickly enable secure internet routing. This is achieved through a process called “beaconing”, in which unforgeable messages originate at a trusted root and travel from network to network.

Through formal verification and dependency analysis, we have deep confidence in the operational stability and security of SCION; deeper than for any other internet architecture. While we were busy designing and analyzing SCION, we also worked on bringing these innovations to the real world. Already today, seven ISPs offer SCION connectivity.

As vaccines roll out globally, we will hopefully soon return to our physically connected lifestyle. However, many of the innovations that were accelerated by the pandemic are here to stay. SCION internet architecture provides a secure and dependable foundation for these innovations today, with its formally verified operation – free of circular dependencies – and growing operational deployment.