IP Is Better Than Ever with SRv6 uSID

IP is the engine behind everything—our favorite streaming services, the global array of IoT sensors connecting people and things, and the workload we access in the cloud. It is the heart of our digital world, connecting us like an invisible and persistent presence in everyday life.

Foreseeing IP market demands

Over the decades, the industry has introduced additional complexity with numerous layers and extensions to the IP protocol, each designed for a specific use case: MPLS in the core, UDP/VXLAN in data centers, GTP in the mobile industry, and NSH for service chaining. While these bespoke solutions may work for their specific use case, they don’t necessarily work together. To cross from one network domain to another, you need expensive gateways that don’t scale or perform as required.

At Cisco, we identified the problem early and conducted in-depth analyses to determine the missing components necessary to make the IP protocol fully self-sufficient and eliminate the need for shim layers.

Enter Segment Routing over IPv6

Segment Routing over IPv6 micro-segment (SRv6 uSID) enables the delivery of any service end-to-end across domains leveraging the IPv6 protocol with no extra layers and without the need for any gateway.

SRv6 uSID has revolutionized IP network architectures by simplifying operations, adding robustness, and delivering best-in-class user experiences across service provider, hyperscaler, enterprise, and data center networks.

The key benefits of SRv6 include:

• Supports any service: SRv6 allows you to build any combination of underlay, overlay, service chaining, security service (VPN, slicing, traffic engineering, more energy efficient routing, fast reroute (FRR), network functions virtualization (NFV)).
• Operates in any domain: SRv6 services can be delivered across all domains, including access, metro, core, data center, host, and cloud.
• Enables end-to-end stateless policy: SRv6 services can be delivered end-to-end across domains using stateless network policy with no need for protocol conversion or gateways at domain boundaries.
• Simplifies and enhances reliability: SRv6 provides a simpler protocol by removing the unnecessary protocol extension layers (UDP/VXLAN, MPLS, NSH), translating into lower costs, higher efficiency, and reliability.
• Improves load balancing: SRv6 provides better load balancing by leveraging the IPv6 flow label to distribute packets more evenly across multiple paths in the network.
• Provides source path control: SRv6 as a source routing technique gives the source (or the application) full control on the forwarding path in a stateless manner. This allows better traffic placement and load balancing for GPU-to-GPU communication in AI backend networks.

These advantages show how SRv6 is changing the game, proving it’s a key technology for the future of networking.

Driving SRv6 innovation since 2016

Cisco invented the SRv6 uSID concept after extensive analysis of IP protocol limitations. We committed to building a robust ecosystem and ensuring standardization. Leading the SRv6 standardization at the IETF, Cisco has ensured every component is fully standardized.

In 2019, we launched SRv6 uSID across our portfolio, marking a milestone in IP networking. By 2021, the first deployment occurred, and today, over 85,000 Cisco routers use SRv6 uSID, highlighting its widespread adoption and impact.

Where is SRv6 now? On the MPLS & SRv6 AI Net World Congress main stage

At the 2025 MPLS & SRv6 AI Net World Congress, SRv6’s growing significance in modern network architectures was highlighted. Key innovations included optimized load balancing in AI backend networks, addressing the challenges of long-lasting, high-volume traffic flows with low entropy for ECMP.

Rita Hui from Microsoft discussed SRv6’s role in AI backend networks for enhancing traffic management, scalability, flexibility, reliability, and redundancy. Alexey Gorovoy from Nebius shared how SRv6 enables unified end-to-end network design across data center and WAN domains, replacing legacy VXLAN and MPLS designs.

Rakuten Mobile and Cisco announced a major milestone with one of the world’s largest SRv6 uSID IP transport networks, promising unprecedented speed, agility, and on-demand services for Japanese businesses.

Cisco Agile Services Networking, an architecture for AI connectivity, leveraging SRv6 uSID

We are moving into the next era of programmability with Cisco Agile Services Networking, an architecture designed to power AI connectivity and customer experiences. Agile Services Networking delivers improved experiences for residential, business, and mobile services with a network that can behave more autonomously, making it simpler and more cost-effective to build, operate, and scale from locations closer to end users.

SRv6 is a foundational technology for the Cisco Agile Services Networking architecture, providing end-to-end network policy and programmability. This allows for intelligent service delivery to capture revenue by making data and network capabilities consumable.

Getting started with SRv6: Join us at Cisco Live

Interested in segment routing and SRv6 uSID? Check out these previously hosted Cisco Live sessions—or, better yet, join us at Cisco Live in San Diego in June.

• SRv6 uSID overview: This Cisco Live session that was held in Amsterdam helps you learn the basics and see real use-case demonstrations like Layer 3 VPN and traffic engineering.
• Segment routing introduction: This Cisco Live session from Amsterdam covers MPLS and IPv6 fundamentals, benefits of segment routing, and a testimonial from Rijkswaterstaat (RWS) in the Netherlands.
• Advanced SRv6 uSID and IP measurements: In this presentation, Alexey Gorovoy of Nebius discusses cutting-edge use cases and front-end data center design, plus advancements in IP measurements achieving 14 million probes per second.
• Service provider trends: This session explores how segment routing supports autonomous networking and network as a service (NaaS) for B2B services.

Register to join us at Cisco Live Americas in San Diego, and check out

these upcoming segment routing sessions to learn more

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