Segment Routing Advancements in Enterprise Networks

February 2018 · Reading time: 11 mins

Introduction

In 2018, enterprises explore Segment Routing (SR) as a scalable and simplified alternative to traditional MPLS-TE. SR encodes routing paths into packet headers, eliminating the complexity of state-heavy signaling protocols like RSVP-TE. With native support in major platforms, enterprise networks gain agility, deterministic routing, and programmability.

Replacing RSVP-TE with Segment Routing

Traditional MPLS-TE implementations demand heavy control plane state. SR allows the source router to define an explicit path by stacking labels (segments), making intermediate routers stateless and efficient. Enterprises use this to engineer traffic across multi-domain and hybrid WANs without RSVP.

Core Building Blocks

• Node-SIDs: Identify routers and inject routing instructions
• Adjacency-SIDs: Describe interface-specific routing decisions
• Prefix-SIDs: Enable fast prefix-based forwarding
• Binding-SIDs: Abstract path policies for reuse

These SIDs form instruction lists in packet headers, which routers interpret to forward traffic precisely.

Deployment in Enterprise WANs

Enterprises deploy SR-MPLS between data centers and regional hubs. SR offers traffic control based on application policies and reduces protocol overhead. In hybrid topologies, SR integrates with SD-WAN controllers to enforce policy-driven forwarding between MPLS, DIA, and private links.

SRv6 Emerges

Enterprises adopting IPv6 evaluate SRv6 as the next evolution. SRv6 encodes instructions in the IPv6 Segment Routing Header (SRH), enabling service chaining, load balancing, and network slicing—all via native IPv6 infrastructure. Programmable edge nodes steer traffic without relying on tunnels.

Enterprise Case Study

A financial services firm uses SR-MPLS to enforce latency-sensitive paths between regional offices. They stack Node-SIDs for predictable app delivery and reduce congestion on backup routes. Meanwhile, a global manufacturing company pilots SRv6 to segregate IoT telemetry from business-critical ERP flows using device-aware policy enforcement at ingress routers.

Migration Considerations

• Ensure support for SR extensions in routing protocols (OSPF, IS-IS)
• Enable SRGB configuration and SID allocation policies
• Deploy centralized controllers (e.g., Cisco NSO, Juniper NorthStar) to orchestrate SR policies
• Monitor SID consumption and enforce domain boundaries for scale

Operational Benefits

SR reduces control plane complexity and streamlines traffic engineering. It allows enterprises to optimize link usage, automate failover, and control performance paths dynamically. Combined with telemetry and analytics, SR supports intent-based networking goals.

Conclusion

In February 2018, SR gives enterprises a lightweight, deterministic, and programmable routing mechanism. Whether using SR-MPLS or SRv6, IT leaders architect future-ready WANs without the legacy burdens of RSVP-TE. Adoption momentum builds as vendors ship mature SR capabilities in their mainstream platforms.

Eduardo Wnorowski is a network infrastructure consultant and Director.
With over 23 years of experience in IT and consulting, he helps organizations maintain stable and secure environments through proactive auditing, optimization, and strategic guidance.
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