Senior Network Engineer (Routing & Switching Specialist) - freelance - hybrid, London, UK
Comgent · Greater London, England, United Kingdom
IT Services and IT Consulting · 11-50 employees
About the role
The role involves auditing and documenting a large-scale legacy Cisco network while remediating non-standard routing configurations. You will also support the transition to a target-state architecture and act as a subject matter expert during change approval board reviews.
What they look for
Requirements
Candidates must possess expert-level knowledge of Cisco routing and switching, including experience with Nexus platforms and complex protocol troubleshooting. Proficiency in network documentation and familiarity with Cisco ACI and spine-leaf architectures are essential requirements.
Full description
Working closely with the Senior Network Architect, this hands-on engineering role is focused on the practical remediation and documentation of a complex, legacy Cisco environment. The successful candidate will be a routing expert capable of diagnosing and unpicking unconventional protocol configurations, building standards-compliant designs, and supporting the convergence of two network environments.
Key responsibilities
- Audit and document the existing network estate (~1,000 devices across both banking entities)
- Identify and remediate non-standard routing configurations, including atypical EIGRP deployments
- Define and implement standardised change categories, change risk classifications, and change management templates
- Support the transition from hybrid ACI to target-state architecture
- Develop network documentation and operational runbooks
- Provide detailed input into the network baseline assessment
- Act as a subject matter expert during change approval board (CAB) reviews
- Work with managed service providers to ensure designs and standards are followed during implementation.
Requirements
Must have
- Expert-level Cisco Routing & Switching: IOS, IOS-XE, NX-OS
- Hands-on experience with Cisco Nexus platforms (2K, 5K, 7K, 9K)
- Deep routing protocol knowledge: EIGRP, OSPF, BGP — including troubleshooting of complex or misconfigured environments
- Familiarity with Cisco ACI and spine-leaf fabric architectures
- Proficiency with network documentation tools and diagramming
- Experience working in dual-stack (legacy + modern) environments
- Understanding of network security segmentation and firewall integration
Advantageous
- CCIE or CCNP (Routing & Switching or Data Centre)
- Automation/scripting experience (Python, Ansible, or similar)
- Experience in financial services or similarly regulated environments
Soft skills
- Detail-oriented with a methodical approach to problem diagnosis
- Able to produce clear, well-structured technical documentation
- Comfortable working in a fast-paced environment with competing priorities
- Constructive and collaborative when working with legacy team members and external managed service providers
