Location: Caerphilly (with travel to client / Ministry of Defence sites as required) Clearance: SC (must hold or be eligible); DV highly desirable Salary: 75,000 Bonus Comprehensive Benefits Package About the Role A major Defence programme is seeking a highly skilled Senior Network Infrastructure Engineer to lead the design, implementation and ongoing support of secure, resilient, multi-domain network services. You will work across datacentre networks, secure LAN/WAN, SDN enabled virtualised environments, and deployed operational sites - ensuring high availability, compliance and adaptability in a mission critical environment. Key Responsibilities * Lead the design, configuration and support of secure multi-site LAN/WAN/SDN infrastructure. * Configure and optimise enterprise switching platforms (e.g., Cubic M3X S8G / S24G, Cisco ESS3300 based). * Implement routing protocols including BGP, MPLS, VPLS, and HA technologies. * Configure firewalls, VPNs, IDS/IPS and boundary protection systems. * Support virtualised routing and SDWAN technologies (Cisco Catalyst 8000V). * Act as senior escalation point for complex incidents. * Ensure compliance with MOD security standards and Secure by Design principles. * Maintain documentation, diagrams and CMDB records. * Support accreditation processes (IT Health Checks, CCVAs). * Contribute to network automation (Python, Ansible, PowerShell). * Identify opportunities for architectural improvement. Essential Experience * Extensive multi-site LAN/WAN experience. * Advanced configuration skills on Cisco and Cubic platforms. * Deep knowledge of BGP, MPLS, VPLS and segmentation. * High availability technologies (HSRP/VRRP equivalents). * DNS, DHCP, NAT, IP planning. * Experience in secure or Defence oriented environments. * ITIL?based service management. Desirable Experience * VMware NSX and SDN, SDWAN and virtualised routing, VoIP, QoS, SIEM/log analysis tools. Knowledge of JSP, ISO 27001, NIST. Experience leading technical projects. * Existing SC/DV clearance. Qualifications * Cisco CCNP (required); CCIE desirable. * ITIL v4 Foundation or above. * Degree in Computer Science, Network Engineering or equivalent experience. Personal Qualities * Strong communicator. * Analytical problem solver. * Able to mentor and lead. * Customer centric and proactive. If you are a Senior Network Infrastructure Engineer with experience working in or with the Defence sector and looking for an exciting new challenge, please send your CV to me today.