Core Infrastructure & IT/OT Security Transformation

Core switch modernization, IT/OT segregation, DMZ fiber upgrade, ECMP redundancy and secure management access

COMnet Solutions | Core Infrastructure, Cisco Switching and IT/OT Security Case Study

EXECUTIVE CONTEXT

COMnet delivered a core infrastructure and security transformation program for a critical industrial environment. The engagement retired end-of-life Juniper core switches, introduced high-performance Cisco SE switching, segregated IT and OT traffic using a dedicated OT firewall, upgraded DMZ connectivity from copper to fiber, enabled ECMP on the PMS link, and created a secure management VLAN behind the MPLS firewall. The program was planned for high availability and executed with zero business disruption.

Key Indicators

0 Downtime
IT/OT Segregated
Cisco SE core
Core infrastructure and IT/OT security transformation
Cisco SE | OT Firewall | DMZ Fiber | ECMP | Secure Management VLAN

IMPACT

Eliminated end-of-life Juniper core switch risk and replaced unsupported infrastructure with modern Cisco SE switching architecture.
Reduced industrial cyber risk by physically and logically separating IT and OT traffic through a dedicated OT firewall layer.
Completed core routing and security migration activities with zero reported downtime and no interruption to business operations.
Improved throughput and reliability by upgrading DMZ interfaces from copper to fiber for higher-capacity connectivity.
Strengthened resilience by implementing ECMP on the PMS link, enabling better load sharing and path redundancy.
Improved secure administration by creating a dedicated management VLAN behind the MPLS firewall for controlled network gear access.

MAJOR ISSUES

Core switching infrastructure was running on end-of-life Juniper hardware, increasing operational risk and limiting vendor support options.
The existing IT and OT network design was logically flat, allowing OT traffic to remain dependent on IT firewall controls.
Flat segmentation increased the risk that an IT-side compromise could pivot into operational technology environments.
Core migration carried routing, LACP, cabling, firewall dependency, and traffic-path risks that required meticulous pre-validation.
DMZ copper interfaces limited throughput and reliability for critical perimeter traffic flows.
Secure management access was required to reduce administrative exposure and improve operational control.

HIGHLIGHTS

Engagement Highlights

Decommissioned the legacy Juniper core switching layer and migrated to high-performance Cisco SE switches.
Executed a pre-activity validation phase covering route verification, LACP checks, physical cabling, and cutover readiness.
Introduced a dedicated OT firewall to segregate critical server zones and core OT traffic from the IT security perimeter.
Upgraded DMZ interfaces from copper to fiber to improve bandwidth, reliability, and perimeter connectivity resiliency.
Implemented ECMP on the PMS link to support load balancing, path optimization, and redundant traffic forwarding.
Created a dedicated management VLAN behind the MPLS firewall to support secure out-of-band-style administration.

ARCHITECTURE AND DEPLOYMENT SCOPE

Reference Architecture – Core Modernization and IT/OT

Technical Deployment Scope

Core Switching Layer: Cisco SE switches replaced legacy Juniper core infrastructure, with validated route tables, LACP state, and physical cabling before cutover.
IT Security Zone: IT traffic continued through enterprise firewall controls, with clear separation from OT-bound pathways.
OT Security Zone: A dedicated OT firewall isolated industrial server zones and critical OT traffic from the IT perimeter.
DMZ Connectivity Layer: DMZ interfaces were migrated from copper to fiber to improve throughput and link reliability.
PMS Resilience Layer: ECMP was enabled on the PMS link to provide path redundancy, better load distribution, and failover readiness.
Management Access Layer: A dedicated management VLAN behind the MPLS firewall improved secure administrative access to network devices.
Migration Control Scope: Pre-checks, cutover plans, rollback readiness, route validation, and post-cutover verification governed the migration lifecycle.

KEY STRATEGIES

Operations Assurance Model

Risk-Led Modernization: The program prioritized unsupported core switching, flat segmentation, and OT exposure as business-critical risk areas.
Zero Business Impact Execution: Migration windows, dependency mapping, pre-validation, and controlled cutovers were designed to avoid service interruption.
Segmentation by Design: IT and OT flows were separated using a dedicated OT firewall to reduce lateral movement risk and protect industrial operations.
High-Availability Planning: Routing, LACP, cabling, ECMP, and failover paths were validated before production migration activities.
Perimeter Throughput Optimization: DMZ copper-to-fiber upgrades improved performance and reliability for critical perimeter interfaces.
Secure Administration Model: A dedicated management VLAN behind the MPLS firewall strengthened administrative isolation and access governance.
Future-Ready Infrastructure: Cisco SE core switching created a more supportable, scalable, and standards-aligned network foundation.
Compliance-Aligned Governance: IT/OT segregation and controlled access support industry expectations for critical infrastructure security.

EXECUTIVE TAKEAWAY

COMnet transformed an obsolete and flat network architecture into a secure, segmented, and future-ready infrastructure foundation. By combining Cisco core modernization, IT/OT segregation, DMZ fiber upgrades, ECMP redundancy, and secure management access, the program reduced operational risk while preserving business continuity throughout the migration.

OUTCOME SNAPSHOT

Zero downtime migration across core routing, switching, firewall, and network optimization activities.
Reduced cyber risk through IT/OT segregation and dedicated firewall control for operational technology zones.
Higher infrastructure capacity, supportability, and resilience through Cisco SE switching, fiber interfaces, and ECMP.

TRANSFORMATION SUMMARY