400G Infrastructure in Sofia: A Strategic Step Forward in GNM’s Core Network Expansion

This move marks a significant step in reinforcing the resilience and scalability of GNM’s core backbone network, in response to increasing traffic demand and the growing peer-to-peer traffic volumes across South-Eastern Europe. Clients can now benefit from 400Gbps IX connectivity, alongside enhanced services delivered over GNM’s DWDM network.

The Sofia upgrade goes far beyond simply adding bandwidth. It plays a key role in improving route diversity and ensuring resilient, redundant transit paths for traffic originating from:

• The Balkans;
• Turkey;
• The Middle East;
• The Caucasus.

Technical profile

• DWDM Backbone Hub: Acts as a key node within GNM’s optical backbone, with full support designed to ensure path resilience and seamless recovery during fibre outages. 
• Core Network Node: Built on the modular Arista 7800R3 platform with full component-level resilience, predictable low latency, and scalable port capacity.

Network topology and routing design

The Sofia node routes traffic along two fully independent DWDM paths:

• Via Belgrade (north-west corridor);
• Via a diverse route through Romania.

Both routes are fully integrated into GNM’s in-house DWDM backbone infrastructure, with further onward connectivity towards Bratislava, Frankfurt, Amsterdam, Vienna, Prague, Warsaw, and Stockholm. The partially-meshed topology provides multiple, diverse paths between key locations, improving resilience and optimising latency across the network.

Available services:

• DWDM (100G / 400G): High-capacity optical transport, with automated route protection and failover.
• GNM‑IX: Direct access to one of Europe’s largest Internet Exchange platforms, enabling peering with more than 600 networks for high‑performance, low‑latency interconnection.
• Capacity VLAN: Layer 2 transport with comprehensive SLA and full traffic control.
• Remote IX: IX connectivity without the need for physical presence in the data centre.
• IP Transit: Full Internet routing table with advanced BGP community-based policy control.

Practical outcomes

A European network operator recently deployed a 100G DWDM service at GNM’s Sofia node, utilising both the Serbia and Romania paths with automatic redundancy, alongside a GNM-IX peering port. The results were immediate and measurable:

• 18% reduction in latency to Frankfurt;
• Faster service restoration during network incidents;
• Improved reliability for end customers, thanks to access to additional upstream networks and key content providers via GNM-IX.

The Sofia node is now fully modernised and ready to support growing demands.

Exploring new route options, planning a capacity upgrade, or looking to scale your connectivity? Speak to GNM - we’re here to help with service turn-ups, route testing across the backbone, and more: sales@gnm.net