Level 3 Senior Network Engineer (Cisco ACI required)

Principal Engineer II - Office Hybrid in Dublin, Ireland ICON is a global healthcare intelligence and clinical research organisation united by a mission to bring new medicines and treatments to patients faster. As a values-driven organisation, integrity, collaboration, agility, and inclusion are at the heart of how we work and interact with each other, customers, patients and suppliers. Role Summary The Level 3 Senior Network Engineer (Principal Engineer II) serves as the highest technical escalation point within the Global Network Operations team. This role is responsible for providing technical leadership, resolving complex network issues, supporting global infrastructure projects, and ensuring the stability, security, and availability of the enterprise network. The ideal candidate should have 10+ years of hands-on enterprise networking experience, with strong expertise in Cisco ACI, Fortinet Firewalls, NetScaler/F5 Load Balancers, SD-WAN technologies (preferably CATO), enterprise routing and switching, and cloud networking. The role requires a strong balance of technical expertise, operational excellence, and project delivery within a global enterprise environment. This is an Office Hybrid role requiring 60% office attendance in our HQ in Leopardstown, Dublin 18. Key Responsibilities 1. Technical Leadership & Escalation Act as the highest technical escalation point for critical network incidents and complex infrastructure issues. Lead troubleshooting across multi-vendor enterprise network environments. Perform root cause analysis (RCA) for major incidents and implement permanent corrective actions. Provide technical guidance and mentorship to Level 1 and Level 2 engineers. Participate in Major Incident Management (MIM) calls and lead technical recovery efforts. 2. Network Operations Ensure the availability, stability, and performance of the global network infrastructure. Support BAU operations involving routing, switching, firewalls, SD-WAN, load balancers, VPNs, DNS, and cloud networking. Identify recurring operational issues and implement proactive improvements to reduce incidents. Perform advanced troubleshooting across on-premises and cloud network environments. 3. Infrastructure & Project Delivery Lead network implementation activities for global infrastructure projects. Design, review, and implement network solutions in accordance with enterprise standards. Support datacenter migrations, office deployments, cloud connectivity, and technology refresh initiatives. Review implementation plans and provide technical approval for high-risk network changes. Support mergers, acquisitions, and global expansion initiatives from a networking perspective. 4. Enterprise Network Technologies Provide technical ownership, administration, and support for: Cisco Core Networking (including ACI) Cisco Meraki and Cisco ISE Fortinet Firewalls NetScaler/F5 Load Balancers SASE platforms (CATO preferred) BGP, OSPF, and enterprise routing Network segmentation and micro-segmentation Azure and AWS networking Ability to automate Network tasks using scripts such as Ansible, Python, Power shell Network performance analysis and packet capture (Wireshark/TCPDump) Network monitoring platforms such as ThousandEyes, SolarWinds, Site24x7, or equivalent 5. Security & Compliance Ensure network infrastructure complies with enterprise security standards and industry best practices. Review and approve firewall policies, NAT rules, VPN configurations, and network segmentation. Support vulnerability remediation activities and security audits. Work closely with Cyber Security teams during incident investigations. Implement secure network designs for new business requirements. Skills & Qualifications Experience Minimum 10+ years of enterprise networking experience. Strong experience supporting large-scale global network environments. Experience working in 24x7 operations supporting mission-critical infrastructure. Proven experience leading major incident resolution and infrastructure projects. Soft Skills Strong analytical and problem-solving skills. Ability to lead technical discussions and major incident calls. Excellent communication and stakeholder manageme