As data centers evolve to support cloud-scale applications, AI workloads, and highly automated operations, networking architectures are under renewed scrutiny. Traditional IP underlays—built on familiar protocols and stable design patterns—have served enterprises well for years. However, emerging technologies like Segment Routing (SR) are raising an important question for architects and engineers working toward CCIE Data Center expertise: Will Segment Routing replace traditional data center underlays?

This SEO-optimized blog takes a neutral, practical look at Segment Routing in data centers, its benefits, limitations, and whether it is likely to replace or complement existing underlay designs.

Understanding Traditional Data Center Underlays

Most modern data centers today rely on a Layer 3 leaf–spine underlay. This approach emphasizes:

  • Simple IP routing
  • Equal-cost multipath (ECMP) forwarding
  • Fast convergence and predictable behavior
  • Clear separation between underlay and overlay

Protocols like OSPF, IS-IS, or BGP are commonly used to build stable underlays that support VXLAN EVPN overlays. This model is well understood, widely deployed, and operationally proven at scale.

What Is Segment Routing?

Segment Routing is a modern routing paradigm that simplifies traffic engineering by encoding the path a packet should take directly into the packet header.

At a high level, Segment Routing:

  • Eliminates the need for traditional MPLS signaling protocols
  • Uses source routing concepts
  • Supports both MPLS (SR-MPLS) and IPv6 (SRv6)
  • Enables fine-grained traffic steering

Instead of relying on hop-by-hop decisions, Segment Routing allows the ingress node to define the packet’s path through the network.

Why Segment Routing Is Gaining Attention in Data Centers

Segment Routing has gained traction in service provider and large-scale environments, and data center architects are beginning to explore its potential.

Key drivers include:

  • Simplified traffic engineering
  • Reduced control-plane complexity
  • Better integration with automation and intent-based networking
  • Improved path control for latency-sensitive applications

As data centers grow in scale and complexity, these benefits become increasingly attractive.

Potential Benefits of Segment Routing in Data Centers

1. Simplified Control Plane

Segment Routing removes dependency on protocols like LDP or RSVP, reducing the number of moving parts in the control plane.

2. Traffic Engineering Without Overlays

SR enables deterministic traffic paths directly in the underlay, potentially reducing reliance on overlay-based traffic engineering.

3. Better Automation Alignment

Segment Routing integrates well with software-defined controllers and automation frameworks, enabling intent-based path selection.

4. Support for Advanced Use Cases

Latency-sensitive workloads, AI clusters, and east–west traffic optimization can benefit from precise path control.

Challenges of Replacing Traditional Underlays

Despite its advantages, Segment Routing faces several practical challenges in data center environments.

Operational Complexity

While SR simplifies some aspects, it introduces new concepts that operations teams must master, including segment lists and path computation.

Hardware and Platform Support

Not all data center switches fully support SR-MPLS or SRv6 at scale, especially in leaf–spine environments.

Integration with Existing Designs

Most enterprises already operate VXLAN EVPN overlays on top of traditional underlays. Replacing the underlay introduces risk without clear immediate returns.

Limited Enterprise Adoption

Unlike service provider networks, enterprise data centers have not yet widely standardized on Segment Routing, making best practices less mature.

Will Segment Routing Replace Traditional Underlays?

In the near to medium term, a full replacement is unlikely.

Traditional underlays remain:

  • Stable and predictable
  • Easier to operate at scale
  • Well-integrated with VXLAN EVPN designs
  • Supported by mature tooling and expertise

For most enterprises, the underlay’s role is to provide reliable IP reachability, not complex traffic engineering. Segment Routing may be considered excessive for that purpose.

A More Likely Future: Coexistence and Selective Adoption

Rather than full replacement, Segment Routing is more likely to complement traditional underlays.

Possible adoption patterns include:

  • Use of SR in spine or core layers
  • Integration with fabric automation and controllers
  • Selective deployment for specific traffic engineering use cases
  • Gradual experimentation in large-scale or hyperscale environments

This hybrid approach allows enterprises to benefit from SR capabilities without disrupting proven designs.

What This Means for Data Center Engineers

For engineers working in modern data centers, Segment Routing represents an important emerging skill, not an immediate replacement technology.

Professionals are increasingly expected to:

  • Understand SR concepts and use cases
  • Evaluate where SR adds real value
  • Design simple, resilient underlays first
  • Integrate new technologies without compromising stability

This architectural mindset is especially important for senior and expert-level roles.

Segment Routing vs Simplicity: The Key Trade-Off

One of the most important lessons from large-scale deployments is that simplicity scales better than sophistication.

Traditional underlays succeed because they:

  • Fail predictably
  • Are easy to troubleshoot
  • Minimize operational surprises

Segment Routing must demonstrate similar operational maturity in enterprise data centers before widespread replacement becomes realistic.

Conclusion

Segment Routing brings powerful traffic engineering and automation-friendly capabilities to modern networks, and its relevance in data center design will continue to grow. However, it is unlikely to fully replace traditional underlays in the near future. Instead, enterprises will adopt Segment Routing selectively, where its benefits clearly outweigh operational complexity. In conclusion, understanding both traditional underlay design and emerging technologies like Segment Routing is essential for future-ready architects—and mastering this balance is best achieved through structured learning and hands-on experience offered by CCIE Data Center Training, which prepares professionals to evaluate, design, and operate next-generation data center networks with confidence.