Lead Network Design Engineer (L3/3.5)

Key Responsibilities

• Network Architecture & Design 

  • Design and govern enterprise network architectures across datacentres, public cloud and corporate environments. 

  • Define standards, patterns and roadmaps for routing, switching, firewall, DNS and load balancing technologies. 

  • Lead network design reviews, technical governance and architectural decision-making. 

  • Design highly available and resilient network solutions supporting business-critical applications and customer-facing platforms. 

  • Develop network standards covering segmentation, availability, performance and security. 

  L3 / L3.5 Engineering & Technical Leadership 

  • Act as a senior escalation point for complex network incidents and major service outages. 

  • Perform deep root-cause analysis across LAN, WAN, cloud and security platforms. 

  • Provide technical leadership during major incidents and high-risk infrastructure changes. 

  • Lead troubleshooting activities across routing, switching, firewall, DNS and application delivery environments. 

  • Mentor network engineers and support technical capability development across the team. 

  Cloud & Hybrid Connectivity 

  • Design and support network architectures within AWS, and some work in Azure environments. 

  • Build and maintain secure hybrid connectivity between cloud platforms, datacentres and customer environments. 

  • Design and support:  

  • AWS VPCs 

  • Transit Gateways 

  • Route Tables 

  • Direct Connect 

  • Site-to-Site VPNs 

  • Security Groups 

  • Network ACLs 

  • Support Azure networking including:  

  • Virtual Networks 

  • ExpressRoute 

  • VPN Gateways 

  • NSGs 

  • Virtual WAN 

  Security Engineering 

  • Design, implement and maintain network security controls. 

  • Govern firewall policies and segmentation strategies. 

  • Support security initiatives including Zero Trust, segmentation and hybrid-cloud security architectures. 

  • Partner with Security Operations teams to ensure secure and compliant networking services. 

   

  AI & Automation Responsibilities 

  A key objective of this role is driving the next generation of intelligent network operations. 

  The engineer will: 

  • Design and build AI-driven operational solutions. 

  • Develop automation frameworks for network discovery, inventory management and topology mapping. 

  • Use AI and machine learning techniques to improve:  

  • Incident triage 

  • Fault identification 

  • Capacity forecasting 

  • Configuration validation 

  • Performance optimisation 

  • Change impact assessment 

  • Build automated network documentation and topology generation capabilities. 

  • Develop predictive capacity and utilisation reporting. 

  • Implement Infrastructure and Network as Code principles. 

  • Leverage APIs, Python, Terraform, Ansible, PowerShell and AI-assisted development tools such as GitHub Copilot, Claude Code and similar engineering platforms. 

Essential skills & experience:

• Routing & Switching 

  • Cisco Catalyst switching platforms. 

  • Cisco Nexus 9000 series. 

  • Advanced knowledge of:  

  • OSPF 

  • BGP 

  • EIGRP 

  • MPLS 

  • VXLAN 

  • STP 

  • HSRP/VRRP 

  • Multicast 

  • QoS 

  • Data Centre network design. 

  Firewalls & Security 

  • Cisco ASA. 

  • Cisco Firepower. 

  • Fortinet FortiGate firewalls. 

  • Firewall policy management. 

  • VPN technologies. 

  • Site-to-site and remote access VPN design. 

  • Network segmentation and Zero Trust principles. 

  Load Balancing & Application Delivery 

  • F5 BIG-IP. 

  • LTM. 

  • GTM/DNS. 

  • WAF. 

  • SSL offload. 

  • Application delivery optimisation. 

  • Traffic management. 

  Monitoring & Visibility 

  • SolarWinds. 

  • Network monitoring and observability platforms. 

  • Capacity management and forecasting. 

  • Network performance analysis. 

  • NetFlow and telemetry solutions. 

  DNS & Domain Management 

  • BIND. 

  • Microsoft Active Directory DNS. 

  • AWS Route53. 

  • Public and private DNS architectures. 

  • Domain management and registrar governance. 

  • DNS security and resilience. 

  • SolarWinds IPAM 

  Cloud 

  • Strong AWS networking experience. 

  • Experience integrating datacentre and cloud environments. 

  • Understanding of Azure networking services would be an advantage. 

Desirable experience:

• • Nutanix AHV, networking & Flow micro-segmentation. 

  • VMware vSphere environments. 

  • SD-WAN technologies. 

  • SASE / ZTNA solutions. 

  • Infrastructure as Code. 

  • AI Ops platforms. 

  • Cloud-native network security products. 

  Qualifications & Certifications 

  Preferred 

  • CCNP Enterprise. 

  • CCIE Enterprise Infrastructure and/or Security. 

  • AWS Advanced Networking Specialty. 

  • AWS Solutions Architect Professional. 

  • ITIL Foundation. 

  Desirable 

  • Fortinet NSE / FCSS certifications. 

  • F5 Certified Technology Specialist (F5-CTS) or equivalent. 

  • Azure Network Engineer Associate. 

Key Attributes

• • Strong design and systems-thinking mindset. 

  • Able to challenge existing approaches and drive continuous improvement. 

  • Passionate about automation and operational excellence. 

  • Comfortable influencing technical strategy and governance. 

  • Strong written and verbal communication skills. 

  • Able to lead technical discussions with engineers, vendors and senior stakeholders. 

  • Analytical, data-driven and outcome focused. 

Success Measures

• Reduction in recurring network incidents. 

• Increased automation and reduced manual operational effort. 

• Improved network visibility and documentation accuracy. 

• Improved capacity forecasting and performance reporting. 

• Reduced mean time to identify and resolve incidents. 

• Successful delivery of cloud and infrastructure transformation programmes. 

• Establishment of AI-assisted operational capabilities across the network estate.