La Mort du Dépannage : Pourquoi Nous Avons Arrêté de «Corriger» pour Commencer à Concevoir

Transitioning an ISP from legacy infrastructure to a modern backbone is about more than just speed—it's about moving from a "reactive" culture to a Design-First mindset.

In my recent project with a major ISP client, the goal was clear: Eliminate technical debt and automate for scale.

The Technical Roadblock

The network was struggling with a Layer 2 ceiling. Relying on Rapid Spanning Tree (RSTP), we were capped at 128 VLAN instances. In an ISP environment, this is a death sentence for growth. Furthermore, the reliance on static routes meant the network was fragile, tethered to client infrastructure, and required constant manual intervention.

The Transformation: Segment Routing & Dynamic Intelligence

We broke the ceiling by deploying Segment Routing (SR-MPLS).

Decoupling with BGP & OSPF

We replaced static routes with dynamic protocols, ensuring our core autonomy. The network now recalculates paths in milliseconds, independent of client-side changes.

Segment Routing (SR)

By moving to SR-MPLS, we simplified the control plane and removed the need for complex signaling protocols, creating a "stateless" core ready for massive scaling.

Infrastructure as Code (IaC)

The most significant shift was the move to Ansible and Terraform. We stopped treating routers as individual "boxes" and started treating the network as Code.

Automation

Using AI-assisted Ansible playbooks, we moved deployments from hours to minutes.

Predictability

Terraform ensures our documentation is the "Source of Truth." If it isn't in the code, it doesn't exist in the network.

The Human Impact

Technical success depends on cultural buy-in. A major part of this project was Network Documentation and team education. By shifting the team's focus from "daily firefighting" to "automated design," we unlocked their true potential.

Even the Sales Team was re-equipped. With an MPLS-capable core, they are no longer selling just "bandwidth"—they are selling high-margin, low-latency L3VPNs and guaranteed SLAs.

The Result: A network that is self-healing, automated, and finally—scalable.