IT Infrastructure Engineer (Networks)

Colt Technology Services
London

Why we need this role

We are seeking an IT Infrastructure Engineer (Network) to contribute to the engineering, implementation, support, and optimisation of enterprise network services, supporting office, data centre, and hybrid cloud networking environments.

This is a hands-on engineering role focused on delivering resilient, secure-by-design, and high-performance network platforms using predominantly Cisco technologies, with exposure to Juniper and cloud-native networking. The role will be critical in ensuring network segmentation, security, and scalability across the organisation’s global infrastructure. The role requires solid technical capability, strong troubleshooting skills, and effective collaboration across teams.

What you will do

  • Engineer and support network infrastructure , including:
    • Office / campus networks
    • Data centre networking
    • Hybrid cloud connectivity (Azure, GCP)
  • Implement, support and input to the design of secure, scalable network solutions across:
    • LAN / WAN / Data Centre / Cloud
  • Support and optimise Cisco-based network platforms , including:
    • Routing and switching
    • Cisco ACI (Application Centric Infrastructure)
    • Policy-driven segmentation
  • Support and manage F5 load balancing platforms , including:
    • LTM configuration and optimisation
    • Traffic management and application delivery
    • High availability and failover design
  • Deliver secure-by-design network architecture , including:
    • Network segmentation and micro-segmentation
    • Zero Trust principles
    • Alignment to enterprise security controls
  • Implement, support and input to the design of hybrid networking solutions , including:
    • Connectivity to Azure and GCP
    • VPN and private connectivity models (e.g. ExpressRoute, Interconnect)
  • Troubleshoot and resolve complex network incidents and performance issues across multi-layer environments.
  • Contribute to network automation and standardisation to improve operational efficiency.
  • Produce and maintain high-quality network documentation , including:
    • High-level and low-level designs
    • Network diagrams
    • Runbooks and operational procedures
    • Configuration standards
  • Collaborate with:
    • Security teams (segmentation, network security controls)
    • Cloud engineering teams
    • Platform and infrastructure teams

  • Participate in the on-call rota to support critical network incidents

What we're looking for

Required skills & experience

Good hands-on experience with:

  • Cisco networking technologies (core requirement)
  • Data centre networking and Cisco ACI
  • F5 load balancing platforms

Experience with:

  • Juniper networking technologies (desirable)
  • Hybrid cloud networking (Azure and/or GCP)

Strong knowledge of:

  • Network segmentation and secure network design
  • Routing and switching protocols (e.g. BGP, OSPF)
  • Layer 4–7 load balancing concepts
  • High availability and resilient design

Proven ability to implement, support and contribute to the support of enterprise-scale network environments .

Good troubleshooting experience across:

  • LAN
  • WAN
  • Data centre fabric
  • Hybrid cloud connectivity

Technical competencies

Ability to implement complex technical delivery and provide strong contributions to problem resolution

Strong understanding of:

  • Secure-by-design networking
  • Network segmentation strategies (macro and micro segmentation)
  • High availability, resilience, and fault tolerance

Hands-on experience implementing and operating Cisco ACI environments

Ability to contribute to design decisions in partnership with architecture teams

Preferred qualifications

  • Certifications such as:
  • Cisco (CCNP / CCIE)
  • F5 certifications
  • Cloud networking certifications (Azure / GCP)

Exposure to:

  • Network automation tools (Ansible, Terraform, etc.)
  • Container networking and modern application delivery

Education & Experience

  • Degree in Computer Science, Networking, or related field (or equivalent experience)
  • 3-5 years of experience in enterprise networking

Posted 2026-07-21

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