Resilience of national Internet segments in 2024
Executive summary
- On average, global resilience continued to improve, but at a modest pace — from 25.7% in 2023 to 24.79% in 2024 (lower is better).
- In 2024, Brazil ranked first in both the IPv4 resilience ranking (0.98%) and the IPv6 resilience ranking (2.15%).
- The Netherlands and Germany took second and third place in both rankings in 2024, with results of 2.54%/3.4% and 2.54%/3.6% respectively.
- The adoption of IPv6 continues to slow down. Partial IPv6 connectivity also remains an issue — some Tier-1 operators still do not peer with each other.
- The current resilience ranking of national Internet segments is available here.
Research objectives
Internet connectivity at the network level is based on how autonomous systems (ASes) are interconnected. A larger number of alternative routes between them increases the resilience of national Internet segments and reduces the risk of outages.
The global reachability of any AS — regardless of its scale, from an international carrier to a small regional provider — is determined by the number and quality of its connections to Tier-1 providers. These are the largest operators that enable traffic exchange between countries and continents. If an AS loses connectivity with even one of its Tier-1 providers, it is very likely to become unreachable in certain parts of the world.
The objective of this study is to assess how the failure of the autonomous system most critical to a national Internet segment (typically the largest provider in that segment) impacts that country’s global connectivity, and to quantify national dependence on such critical operators.
Resilience assessment methodology
The study is based on modeling the failure of a single autonomous system (AS). The main question we aim to answer is: what share of ASes in a given region would lose connectivity to Tier-1 providers and therefore lose global reachability in the event of such an incident?
Theoretically, the architecture of BGP and inter-domain routing assumes that every non-transit AS should have at least two upstream providers to ensure resilience in case one of them fails.
In practice, though, the situation is different: as of 2024, around 41.2% of Internet providers worldwide had connectivity to only one IPv4 upstream operator, and for IPv6 this figure was even higher at 47.8%. As outages at transit operators occur regularly, the question of connectivity degradation is not if but when.
To assess the resilience of national Internet segments, we model the failure of a single autonomous system using a methodology that has remained consistent for nine years. The assessment algorithm includes the following steps:
- Using the AS relationship model in Qrator.Radar, we compute all alternative paths to Tier-1 providers for every AS in the world.
- Using the MaxMind GeoIP database, we map the address space of each AS to the countries in which its prefixes are announced.
- We assign every AS in a given country a weight equal to the share of its address space announced in that country.
- We calculate a country’s weight as the sum of the weights of all ASes operating within its territory.
- For each AS, we calculate how its potential failure would affect the reachability of other ASes in the region.
- In each country, we identify the critical AS — the one whose failure would cause the largest share of ASes to lose global connectivity. We use this share as the resilience metric of the national Internet segment: the lower the value, the better.
IPv4 resilience
Since 2016, we have been calculating global IPv4 resilience metrics and observing a year-over-year trend toward higher Internet reliability.
We use both average and median values to smooth out the effect of sharp resilience drops in countries with a small number of local ASes, where each individual AS can significantly influence the final metrics. This approach also helps mitigate cases where a monopoly of a single AS within a country — with a 100% share — would otherwise distort the overall assessment of global stability.
The trend of gradual improvement in resilience continued in 2024. The median value saw a slight increase — from 18.64% in 2023 to 18.89% in 2024 — while the average decreased more noticeably, from 25.72% to 24.79%.
IPv4 resilience ranking
Below are the top 20 countries by their resilience level in the event of a critical AS failure. From a practical perspective, this means that these countries have a highly connected Internet infrastructure. The percentage shown reflects the share of ASes that would lose global reachability in the event of a failure of the most significant network operator.
🇧🇷 Brazil leads IPv4 resilience ranking, followed by 🇳🇱 the Netherlands and 🇩🇪 Germany
In 2024, Brazil remained the most resilient country in the IPv4 ranking, maintaining the lowest dependence on a single critical AS. The Netherlands and Germany again held the next two positions. This indicates a stable level of resilience among the leaders.
🇸🇨 Seychelles ranks 4th in global IPv4 resilience
Seychelles jumped 11 positions upward and finished in 4th place, coming close to the top three. This was made possible by a major improvement in the country’s network infrastructure.
Like many island nations, Seychelles has been heavily dependent on intercontinental submarine fiber-optic cables. For many years, it relied on a single connection to the mainland — the Seychelles to East Africa System (SEAS) cable, with a design capacity of only 1.9 Tbit/s. Under such conditions, redundancy was only possible via satellite links, which remained too expensive for most providers.
The situation changed radically between 2022 and 2024, when two new international submarine cables were connected to the islands:
The deployment of new submarine cables dramatically increased available bandwidth and connected Seychelles to the global transit market, attracting major international providers such as Liquid, PCCW Global, Arelion, Seacom, GTT, Cogent, and Tata. Competition between them reduced the price per megabit and made route redundancy affordable for most local ISPs.
As a result, nearly all operators in Seychelles began using at least two external providers, enabling full path redundancy. If one transit provider goes offline, global reachability is maintained. This improvement helped Seychelles enter the global top 4 in the IPv4 resilience ranking.
🇹🇭 Thailand jumped from 35th to 14th place in the IPv4 resilience ranking
Thailand made the most remarkable leap in the ranking — from 35th to 14th place. The country’s critical autonomous system remains AS38082 (True Internet Corporation), but its share has decreased, improving Thailand’s overall IPv4 resilience.
Notably, several other countries from the APAC region also entered the top 20, including Cambodia, Indonesia, and Hong Kong. As a result, four out of five new entrants this year are Asian countries — a trend that may indicate strengthening international connectivity across the region.
It is difficult to pinpoint a single reason for Thailand’s rapid progress. A likely factor is the expansion of international bandwidth through new submarine cables, including the Asia Direct Cable (ADC), which was put into operation at the end of 2024.
Such projects increase the number of alternative routes, help reduce traffic costs, and create favorable conditions for redundancy. As a result, local ISPs gain access to multiple external transit providers, directly enhancing the resilience of national Internet segments.
🇯🇵 Japan dropped out of the top 20 in the IPv4 resilience ranking
In 2024, Japan fell out of the top 20, dropping from 16th to 45th place. The main reason was a change in the country’s critical autonomous system: AS2497 (Internet Initiative Japan) replaced AS2907 (National Institute of Informatics).
This shift occurred in 2024, when AS2907 began using AS2497 as its only upstream provider. As a result, the entire local customer cone of AS2907 came under AS2497’s control and merged with the latter’s already extensive downstream network.
Consequently, the unavailability of AS2497 would now affect a significantly larger number of local ASes, leading to reduced resilience and Japan’s sharp decline in the ranking.
🇦🇷 Argentina dropped out of the top 20 in the IPv4 resilience ranking
Argentina showed one of the steepest declines in the ranking, falling from 19th place in 2023 to 53rd in 2024. At the same time, the country’s critical autonomous system changed from AS7303 (Telecom Argentina) to AS12956 (Telxius).
The drop was caused by a major national provider, AS52361 (ARSAT), connecting to the Tier-1 operator Telxius, which already served another major Argentine provider, AS22927 (Telefónica de Argentina).
As a result, two of the country’s largest regional operators became dependent on the same Tier-1 provider. The unavailability of AS12956 (Telxius) would now disconnect a significantly larger number of local ASes within the customer cones of both providers, leading to a sharp decline in Argentina’s overall resilience.
🇮🇪 Ireland dropped out of the top 10 in the IPv4 resilience ranking
Finally, the most significant decline in resilience this year: Ireland fell by 50 positions — from 6th place in 2023 to 56th in 2024.
The country’s critical autonomous system changed from AS5400 (BT) to AS1299 (Arelion / Twelve99). The drop was caused by several local operators establishing AS1299 as their only upstream provider, making it the sole transit dependency for a growing share of Ireland’s networks.
IPv6 resilience
Over the years of our observations, IPv6 adoption has grown significantly. According to Google’s statistics, the share of sessions using IPv6 to connect to its services was about 10% at the beginning of 2016 and reached 45.26% by the end of 2023. However, while growth in the early stages of adoption was almost exponential, it has noticeably slowed in recent years: by the end of 2024, IPv6 usage stood at 47.51% — an increase of just a few percentage points over the year.
This trend is also confirmed by APNIC’s annual BGP statistics. Between 2020 and early 2025, the number of IPv6 prefixes doubled, but the annual growth rate has declined significantly: while in 2021 it was nearly 40%, by 2024 it had dropped to around 10%. A similar slowdown can be seen in other indicators, including the total IPv6 address space and the number of autonomous systems.
Partial connectivity in IPv6
One of the persistent characteristics of IPv6 development is the partial connectivity among Tier-1 providers. To illustrate this, we built graphs modeling the “Internet core” for IPv4 and IPv6, where nodes represent Tier-1 providers and edges represent peering links between them.
As can be seen, in the IPv4 model all Tier-1 operators are interconnected through peering relationships, ensuring full connectivity. The IPv6 picture is different: some Tier-1 providers lack direct peering with each other. This means that traffic between their customer cones cannot be exchanged directly, since no routes are shared between them.
Routing traffic indirectly — through a chain of more than two Tier-1 providers or via a lower-tier transit operator — is not possible due to the violation of the valley-free routing principle, which stipulates that prefixes received from a provider or peer may only be advertised to one’s own customers.
Therefore, the absence of routes from regional ASes to at least one backbone Tier-1 provider leads to partial connectivity in IPv6. For end users, this may result in the inaccessibility of certain websites or online services.
A well-known example is the long-standing absence of peering between Hurricane Electric (AS6939) and Cogent (AS174). A temporary connection appeared briefly in 2023, lasted about a month, and raised hopes that cooperation between the two providers might finally be established. However, the link did not reappear throughout 2024.
IPv6 resilience ranking
Similar to the IPv4 ranking, the top 20 countries listed below for IPv6 reflect their resilience level in the event of a critical AS failure. The ranking shows how stable the global connectivity of each national Internet segment would remain if its most significant network operator were to go offline. The percentage indicates the share of autonomous systems in a given country that would lose global reachability in such a scenario.
🇧🇷 Brazil ranked first in IPv6 resilience
Brazil, which has consistently held the top position in our IPv4 resilience ranking, this year rose to first place in the IPv6 ranking as well. It’s a confident lead: the Brazilian segment demonstrated excellent results in both full and partial connectivity. Congratulations to Brazil!
🇳🇱 The Netherlands and 🇩🇪 Germany changed their critical AS in IPv6
The Netherlands and Germany, both ranked among the top three countries in IPv6 resilience, changed their critical autonomous systems in 2024. For both countries, the new critical AS became AS174 (Cogent) — one of the most rapidly expanding Tier-1 providers.
Notably, among the top 15 countries in the IPv6 resilience ranking, four now have AS174 as their critical AS.
Cogent is known for its periodic de-peerings with other Tier-1 providers. For instance, in February 2024, the de-peering between Cogent and NTT in Europe drew significant attention, followed by another one in May between Cogent and the Asian branch of Tata (AS6453).
🇱🇻 Latvia — the breakthrough of the year in IPv6 resilience ranking
Latvia demonstrated the strongest improvement in the IPv6 resilience ranking this year, jumping from 41st to 15th place. This significant progress resulted from a large number of autonomous systems in the country adding secondary upstream providers.
At the same time, the country’s critical AS changed: it is now AS13194 (Bite Lietuva), which surpassed last year’s leader, AS12578 (APOLLO-AS), in the number of single-homed clients.
🇸🇨 Seychelles entered the top 20 in the IPv6 resilience ranking
The island nation significantly improved its position in the IPv6 resilience ranking, rising from 23rd to 11th place. The country also changed its critical autonomous system, which is now AS3356 (Lumen) — a Tier-1 provider. As mentioned earlier in the IPv4 section, this improvement was driven by the launch of two new submarine cables that greatly enhanced the global connectivity of Seychelles.
🇮🇪 Ireland dropped out of the top 20 in the IPv6 resilience ranking
In 2024, Ireland fell out of the top 20 in the IPv6 resilience ranking. This was the result of a change in the country’s critical autonomous system: AS1299 (Arelion), a global Tier-1 provider, replaced the local Internet exchange AS47720. The concentration of local networks using AS1299 as their only upstream provider reduced the overall resilience of the national Internet segment.
🇨🇳 China technically dropped out of the top 100 in the IPv6 resilience ranking
In 2024, China technically fell out of the top 100 in the IPv6 resilience ranking, plummeting from 12th to 136th place. This was caused by massive prefix announcements from AS4538 (CERNET — China Education and Research Network) through rarely used autonomous systems allocated by APNIC. These announcements did not fully propagate across the global Internet, resulting in partial reachability for a significant number of Chinese ASes.
We analyzed this phenomenon in detail in last year’s study on the resilience of national Internet segments. The issue is also related to routing peculiarities involving AS6939 (Hurricane Electric) and AS4635 (Hong Kong Internet Exchange), as well as the absence of a peering connection between AS6939 and AS174 (Cogent).
It is important to note that such anomalies affect our connectivity metrics but may not have a noticeable impact on regular users.
Stub autonomous systems
One of the key threats to the resilience of national Internet segments is the large number of so-called stub autonomous systems whose only provider is the country’s critical AS. We define stub ASes as networks that have a single upstream provider and do not provide transit for any other AS.
The tables below show cases where a country’s critical AS also serves as the main hub for local stub networks. In 2024, the number of such clearly problematic cases declined significantly compared to 2023 (which were around 50% for IPv4 and roughly 75% for IPv6 at the time).
Therefore, we conducted a deeper analysis, also examining cases where a country’s critical AS ranked among the top 3 hubs for stub networks.
IPv4
IPv6
Overall, critical ASes now overlap less frequently with stub providers, yet such providers still represent a significant share of all critical ASes — especially when considering not only the top one but the top three stub hubs.
Other trends
Rising tensions around submarine cables in 2024
The year 2024 was marked by a series of submarine cable incidents. In February, four cables in the Red Sea were damaged, disrupting connectivity for more than 100 million users across Africa and affecting about 70% of traffic between Europe and Asia. In November, cables in the Baltic Sea were severed, and in Vietnam, all five submarine cables serving the country were taken out of service — full restoration took nearly eight months.
Amid rising risks in the South China Sea, construction of alternative routes through Australia and Indonesia accelerated. According to Telegeography, as of September 2024, there were 532 operational submarine cable systems worldwide and 77 more under construction. Around 140,000 km of new cables were laid over the year — three times more than five years ago.
On November 29, the UN established its first advisory body dedicated to submarine cable protection — the International Advisory Body for Submarine Cable Resilience — created jointly by the ITU and ICPC. It includes representatives from several countries as well as major telecom operators and Internet companies.
Sprint (AS1239) leaves the ranks of Tier-1 providers
The major U.S. operator Sprint was acquired by Cogent in late 2022. Shortly after the deal, a restructuring process began, and the number of peers for the AS started to decline significantly. Over the next couple of years, Sprint gradually lost its Tier-1 status.
In May 2024, a final round of mass de-peerings took place, including the termination of connections with other Tier-1 providers such as AT&T, Verizon, and Deutsche Telekom. As a result, we removed AS1239 from our list of Tier-1 providers.
BGP security reaches the national policy level
In September 2024, the Biden–Harris Administration announced the introduction of a national policy aimed at strengthening BGP security. The document, titled Roadmap to Enhancing Internet Routing Security, was developed by the Office of the National Cyber Director (ONCD) in collaboration with CISA.
It outlines recommendations applicable to all types of networks — from service providers to enterprise infrastructures — including risk-based planning, ROA publication, contractual requirements, and continuous monitoring. This marks the first time that routing security and resilience have been formally addressed at the federal level in the United States.
RPKI ROA adoption surpasses 50%
In 2024, for the first time, more than half of all IPv4 and IPv6 routes — about 54% — in the global routing system were secured using RPKI ROA. Around 74% of total Internet traffic is now directed to prefixes covered by valid ROAs.
Over the year, the number of published ROAs increased by 49% (from 188,000 to 280,000), while the number of autonomous systems using ROA grew by 16% to 47,000.
Meanwhile, the number of unique ASPA records increased from 56 to 87, indicating that the adoption of this technology is still at an early stage.
You can find the current resilience ranking of national Internet segments here.
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