Ukrainian Internet during war: how the RETN network keeps in touch with the world

And here, for broadband, mobile operators there is something in common, namely the need to use backbone data networks and cross-border optical connections to European and global networks, which is the global Internet network in its essence. Usually, backbone operators (Backbone/Network Service Provider) are little visible to the average user, but are critical for the availability of the Internet everywhere and always.

Resistance in the first months of the war

In February-March 2022, many optical communication lines were damaged simultaneously due to active hostilities in the Kyiv region. In fact, backbone operators build networks in such a way that in normal times, if one route is damaged, traffic is automatically redirected to another, alternative physical optical link. For example, before the war, 5 physical routes operated to Kyiv only on the RETN network , which guaranteed uninterrupted provision of data transmission services to all operators in Kyiv and throughout Ukraine, and provided optimal RTT to international traffic exchange hubs.

It is important to note here that one cable usually contains many optical fibers used by different providers, and for optics to physically become a network, appropriate equipment is required for transmitting large volumes of data and routing traffic, so if there is a physical infrastructure, each operator configures the necessary bandwidth, taking into account the load on the data transmission network in the event of an accident on an alternative route.

For backbone carriers, data transfer rates are measured in tens and hundreds of terabits per second, and the cost of equipment is in millions of US dollars. The Internet works as a single system, and traffic, in the event of a failure of one of the backbones, is usually directed to other uplinks (the operator is the provider of Internet connectivity).

So in February-March 2022, to ensure the continuity of the Internet, RETN organized backup additional Nx100G channels from Warsaw, Frankfurt, Budapest, Chisinau to Odessa, Kyiv, Zaporizhzhia, Mykolaiv, Lviv, Chernihiv and Uzhgorod together with local and international partners, including «sharing» available bandwidth with competitors (!) to reserve its own main trunks. This allowed us to maintain connection to the global network in the most difficult times, when a large number of optical cables were damaged at the same time. In such difficult circumstances, it did not matter whether you competed in the same market, we supported each other, becoming partners to save the network.

During these months, it was not easy to provide the necessary network bandwidth, and therefore, already in April 2022, although none of the international logistics companies delivered commercial cargo to Kyiv, and with limited working customs in the Kyiv region, the RETN team managed to deliver, clear customs and install the most powerful Juniper MX10008 routers: at that time at the main nodes in Kyiv, and over the following months to modernize its own communication nodes in Lviv, Odessa, Dnipro and Zaporizhia to provide all providers and operators with a sufficient number of ports with 100Gbps interfaces. It is important to note that at that time we had two engineers in the team in Kyiv and one in Kharkiv. Now one of the guys has been mobilized for two years and is heroically defending Ukraine at the front. The technical team managed to replace the equipment without interruptions in communication, and for this they repeatedly had to work at night, during air raids and shelling.

It is worth noting here that trunk optical cables are usually serviced by infrastructure companies that have their own mobile teams and telecommunications laboratories in each region.

From the very beginning of the full-scale invasion, all lines to the east were turned off, and RETN, from the first day of the NCU resolution on blocking Internet resources that pose a threat to the national security of Ukraine, has been blocking all autonomous systems from the Russian Federation and the Republic of Belarus and monitoring and executing all subsequent orders of the NCU.

To improve fault tolerance and improve communication quality, a new DWDM route Odesa — Monastyryshche — Lutsk was launched in July 2022, providing additional backup capacity and the shortest route to Eastern Europe. In simple terms: the Internet hub in Warsaw became accessible to subscribers in Odessa, Cherkasy and Mykolaiv much faster.

War is a challenge not only for network resilience, but also a test of management values, style, understanding of long-term prospects, quick decision-making and the ability to manage a business in times of uncertainty. RETN Group is a private company, headquartered in London, and of course, due to the occupation of part of the territory of Ukraine, RETN lost some of its customers and income, but it was the ability to make decisions very quickly and the understanding of the criticality of the necessary investments that ensured that the RETN network did not have a single node loss in Ukraine due to equipment failure, and Ukrainian providers always had access to the global Internet and, accordingly, all their users (end consumers of services) had access to communication.

We maintain and develop communication

After the first shock months, the war entered a protracted phase, and here the operators had new challenges, since from October 2023, regular shelling of energy infrastructure throughout Ukraine required ensuring uninterrupted power supply for 72 hours from alternative sources.

The international company Cloudflare recorded six major outages in the Ukrainian Internet segment in 2024. It is worth noting that, unlike the recent communication collapse in Spain, these outages were associated with a decrease in traffic and temporary unavailability of some regional provider networks. RETN, for its part, constantly monitors its own network and registers all incidents in real time, and in three years, none of the accidents led to a complete loss of communication in the Ukrainian RETN network.

This stability was achieved through regular investments in equipment, flexible network architecture, its own four cross-border connections with the coherent network RETN Poland, RETN Hungary, RETN Moldova, redundancy of physical DWDM routes and optimal IP/MPLS. RETN currently ranks 11th (according to Caida Rank) among the largest interconnected data networks in the world, and is the only one in the ranking that has built connectivity through investments and network development in Europe and Asia.

RETN is a well-known and trusted partner among the global telecom community, therefore, together with European colleagues, we supported Ukrainian providers not only with stable connectivity and redundant data transmission channels, but as part of the KeepUkraineConnected initiative, we donated a lot of Juniper equipment for IP/MPLS networks for the needs of Ukrainian regional broadband operators, which allowed us to maintain communication quality in difficult conditions.

For the telecom business, stopping development is the first step towards extinction, and, unfortunately, this business, especially backbone networks, requires constant significant investments, including the modernization of DWDM and IP/MPLS equipment.

For example, millions have been invested to ensure stable network operation during blackouts, as all RETN nodes have been equipped with new batteries for the third time, as their service life has been significantly shortened due to the war and regular shelling. These batteries ensure autonomous operation of telecommunications equipment in accordance with the requirements of the National Communications Commission at each reinforcing node of the 6,000-kilometer network in Ukraine.

Now more than ever, the state needs a working, efficient business, attracting European investments and stable budget revenues, so it is critical for RETN not only to stay connected, but also to continue investing in new projects. Fortunately, RETN’s British head office has no doubts about the need and criticality of such investments. Therefore, the company has just completed the modernization of its backbone links to a new solution of 400GE pluggable interfaces.

Plans and prospects for 2025 and beyond

Today, the whole world has turned to the clouds and is actively improving the quality of work through the implementation of AI solutions in life and business. RETN for business has reliable communication channels with the shortest delays and the highest SLA of 99,99%, and provides access to all cloud solutions, both world leaders AWS, Google, Microsoft, Oracle, and Ukrainian DCs, with possible geographical inclusion in Dublin, Frankfurt, Warsaw, Kyiv and almost 1000 nodes across Europe and Asia.

One of the most important investments in 2025 is the launch of a scrubbing center to protect against DDoS attacks in Ukraine. The advantage of the center is that it allows you to clean traffic as close as possible to Ukrainian providers and their users, minimizing delays and increasing the effectiveness of protection.

As for the future, even now Ukraine remains included in several upcoming rather ambitious projects for the construction of new trunk international optical paths. However, these investments have been postponed to the final stage with a deadline «to be specified later.»

Conclusion

The history of the Ukrainian Internet during the war is a story of resilience, flexibility and interaction, an example of indomitability and resistance. RETN became an integral part of the digital front, helping to keep Ukraine reliably connected to the global Internet even in the most difficult moments. And today the company not only maintains communication, but also develops the digital infrastructure of the future through a reliable connection to Europe.