Senior Network Engineer in London

We are in the midst of a major Data Centre Modernisation Programme – replacing end‑of‑life core routers and switches with new Cisco Nexus9300, Catalyst9200, and Catalyst8300 platforms across all sites. The successful candidate will be instrumental in the design, deployment, and ongoing operation of this refreshed network estate and will work in data centres in the UK, US and Switzerland, each having a production and a disaster‑recovery site.

Key Responsibilities

• Network Operations & Troubleshooting
  • Act as the primary technical authority for all data centre network infrastructure, including switches, routers, and firewalls.
  • Independently diagnose and resolve complex network outages, performance degradations, and connectivity issues across all six data centres, minimising reliance on Cisco TAC.
  • Perform root‑cause analysis of incidents and produce detailed post‑incident reports with remediation actions.
  • Proactively monitor network health using SNMP, syslog, Cisco FMC, and enterprise monitoring tools; identify and resolve issues before they impact services.
  • Maintain and execute network operations runbooks for daily monitoring of routers, switches, and firewalls.
• Data Centre Network Refresh Programme
  • Play a lead technical role in the ongoing DC Modernisation Programme alongside our implementation partner – designing, configuring, testing, and deploying new Cisco Nexus9300, Catalyst9200, and Catalyst8300 equipment.
  • Develop and validate detailed cutover plans, runbooks, and rollback procedures for each site refresh.
  • Coordinate with third‑party integrators and Cisco during equipment staging, installation, and validation.
  • Ensure seamless migration from end‑of‑life platforms to the new network architecture with zero or minimal client impact.
• Firewall & Security
  • Manage Cisco Firepower4115HA firewall pairs across all regions using Cisco Firepower Management Centre (FMC).
  • Design and maintain firewall rulesets, NAT policies, VPN tunnels, and DMZ architectures.
  • Evaluate firmware release notes thoroughly before any upgrade to identify breaking changes.
  • Support ISO27001 and SOC2 compliance requirements relating to network security controls.
• WAN & Office Connectivity
  • Support AzurevWAN connectivity between Cisco Meraki office sites and data centres.
  • Assist with IPsec site‑to‑site VPN configuration between MerakiMX appliances and Azure gateways.
  • Provide escalation support for EUC teams for Meraki office network issues where required.
• Change & Configuration Management
  • Follow and champion ITIL‑aligned change management processes for all network changes.
  • Maintain accurate network documentation, topology diagrams, IP address management (IPAM), and configuration backups.
  • Participate in Change Advisory Board (CAB) reviews and produce change implementation plans.
• Collaboration & Continuous Improvement
  • Work closely with the infrastructure, VMware, storage, and information security teams.
  • Mentor and upskill junior engineers on Cisco technologies and network best practices.
  • Identify opportunities to automate repetitive network tasks using scripting (Python, Ansible, PowerShell).
  • Contribute to capacity planning and network architecture decisions as the business scales.

Skills & Experience Required

• Data Centre Networking
  • 5+ years managing Cisco switches and routers in a multi‑site data centre environment.
  • Expert‑level Cisco NX‑OS (Nexus9000 series) and IOS‑XE (Catalyst) experience.
  • Hands‑on Nexus9300 deployment, VPC, vPC fabric configuration.
  • Catalyst9200 access‑layer switching; VLAN design; spanning tree (RSTP/MST); port‑channels; Layer2/3 boundaries.
• Firewalls & Security
  • 3+ years managing Cisco Firepower / FTD firewalls in HA.
  • FMC administration, policy design, NAT, VPN management.
  • Strong understanding of DMZ architecture, ACLs, and zone‑based security.
  • Firmware upgrade planning including release‑note analysis for breaking changes.
• Routing Protocols
  • Solid BGP experience (eBGP peering, route policy, prefix lists, AS‑path filters).
  • OSPF multi‑area design and troubleshooting.
  • Static routing and policy‑based routing.
• WAN & Office Networking
  • AzurevWAN / VPN Gateway fundamentals.
  • IPsec site‑to‑site VPN configuration and troubleshooting.
• Automation & Scripting
  • Comfortable with CLI‑based configuration at scale.
  • Experience scripting with Python or PowerShell for network tasks.
• Compliance & Governance
  • Experience working in an ISO27001 and/or SOC2 certified environment.
  • Understanding of change management (ITIL) processes.
• Soft Skills
  • Proven ability to remain calm and methodical under pressure during outages.
  • Self‑starter who can work independently with minimal supervision.
  • Strong documentation and communication skills.
  • Willingness to participate in an on‑call rota and work outside business hours for planned changes.

Certifications Required: CCNP Enterprise (or equivalent demonstrated experience at CCNP level); demonstrable skills at or above CCNA level.

Desirable: CCIE Enterprise Infrastructure (or progress towards); Cisco Certified DevNet Associate; Cisco Firepower / FTD Specialist; Microsoft Azure Network Engineer Associate (AZ‑700); ITILv4 Foundation.

Working Arrangement: Hybrid – minimum 2 days per week in the Morae London office. Occasional travel to UK and international data centre sites may be required for refresh deployments and incident response.

Hours: Standard business hours with participation in an on‑call rota to support the 24/7/365 production environment. Planned maintenance windows typically occur outside business hours.

Travel: Occasional travel to data centre sites in the UK, US, and Switzerland as required for major deployments, audits, or critical incident support.