Key duties and responsibilities• Design, configure, implement and support Cisco ACI environments.• Configure and manage ACI fabrics, including APIC, leaf and spine architecture, tenants, VRFs, Bridge Domains, EPGs, contracts and policies.• Manage integration between Cisco ACI and external networks, firewalls, load balancers and other infrastructure. • Configure, administer and troubleshoot Fortinet FortiGate firewalls and associated security infrastructure.• Develop and maintain firewall policies, NAT rules, VPNs, routing, security profiles and access controls. • Support Forti Manager and Forti Analyzer environments where applicable.• Manage complex Layer 2 and Layer 3 networking environments, including BGP, OSPF, VLANs, VRFs, VXLAN/EVPN, TCP/IP and network segmentation.• Troubleshoot complex network connectivity, latency, routing, firewall and application communication issues.• Perform root-cause analysis for network and security incidents and implement permanent remediation.• Support network upgrades, migrations, capacity planning, patching and lifecycle management.• Implement network security controls in accordance with organisational cyber security policies and industry best practices.• Monitor network availability, performance and security and proactively address emerging issues.• Develop and maintain technical documentation, network diagrams, configuration standards, operating procedures and implementation plans.• Participate in change management, incident management and problem management processes.• Work collaboratively with infrastructure, cloud, cyber security, application and architecture teams. • Provide technical guidance and mentoring to other network engineers.• Participate in after-hours implementation activities and on-call support where required.