Overview
Location: North Greenwich, London/ Hybrid
Contract Type: Permanent
Salary: £62,000 - £70,000 plus fantastic benefits
UK Sponsorship available; however, candidates are responsible for their own application fees.
Hybrid working within this role enables a balance of 50 per cent of time split between the office and home over a 4-week period. Hybrid working arrangements can evolve subject to business requirements.
Key Technologies: Network Security (inc. Firewalls), Routing and Switching (WAN/LAN/Datacentre), SDN, Wi-Fi and Cloud Networks.
About Us: The Networks and Hosting Team, within Tech and Data, maintains the infrastructure that underpins our services across TfL. The Network team is engaged in large-scale network improvement projects including firewall upgrades, network consolidation and integration, and widescale WAN and data centre refreshes.
About the Role
The Senior Infrastructure Security Engineer reports to the Network Assurance Manager and provides specialist technical knowledge, experience and leadership to assure, support and optimise IT Access, WAN, data centre and Cloud network infrastructure. Working in a 24/7 operational environment, you will maintain technologies, assure deployments, and pursue continuous improvement and automation of repeatable tasks. You will have in-depth knowledge of networking technologies including network security (firewalls) and routing and switching across campus and data centres, and will lead Network Assurance team members while collaborating with the Network Transformation Portfolio, Infrastructure teams, Network Architects and Application Support and Development Management to support business-critical services and deliver high-profile projects aligned with organisational priorities and vision.
Main Duties
* Ensure operability of TfL's information technology networks, including incident management, investigation and resolution to maximise system availability for critical business services in line with agreed service levels.
* Own and assure all operational network activities, including change, requests and network design architectures, ensuring networks align with approved designs and implementations are fit for purpose.
* Provide guidance and technically lead and mentor the Network team in the delivery of BAU services, project work activities and continual improvements to processes and service.
* Lead accurate and timely reporting of the technical environment using monitoring and reporting tools; rectify operations outside normal state; ensure HW, SW and service configuration elements are recorded correctly.
* Capacity Management: identify and drive activities to mitigate risks in the Network environment.
* Service and Process Improvements; identify, shape and drive improvements to technology or processes, focusing on standardisation and automation to reduce manual effort; provide recommendations for innovative solutions.
* Collaborate with technology colleagues and teams to deliver project outcomes; provide SME input and contribute to the design process as required.
* Identify technical dependencies, risks and issues to maintain vendor, statutory and TfL compliance levels.
* Forecast activity trends and proactively implement improvements to maintain up-to-date, stable and secure technologies.
* Supplier Management: manage suppliers' adherence to SLAs; work with vendors to minimise service disruption and ensure value is realised.
* Assure network activities meet TfL policies and standards; ensure Capex spend aligns with business priorities and is cost-efficient.
* Maintain knowledge of industry developments and trends in Network and Network Security technologies.
* Develop time management to build skills and provide technical leadership; mentor junior team members.
Knowledge and Skills
Essential
* Demonstrable high-level knowledge of networking technologies including:
* Firewalls
* Switching technologies (VLANs, trunks, STP, vPC, VDC, VXLAN, multi-layer switching and EtherChannel)
* Routing technologies (EIGRP/OSPF/iBGP/eBGP) and router redundancy (HSRP, VRRP, GLBP)
* QoS in a LAN/WAN environment
* Strong troubleshooting skills and willingness to learn; able to work autonomously and with initiative
* Experience supporting firewalls including policy and VPN; able to use CLI to manage devices
* Knowledge of Cisco and major firewall vendors' software and hardware
* Analytical with ability to identify trends and proactively mitigate service-affecting issues
* Clear communication tailored to different audiences
* Proficient in risk identification and mitigation planning
* Experience working with suppliers, internal teams and customers to deliver component technologies
* Mentoring and coaching to support Engineers' development
Desirable
* Knowledge of network security products such as proxy servers and application delivery controllers
* Knowledge of other networking technologies such as load balancers
* Knowledge of SDN, cloud networking, Wi-Fi and network automation (e.g., Python)
* Knowledge of other major networking vendors’ software/hardware
* Understanding of relevant legislation for Government/Public Sector IT (e.g., Data Protection Act, EU Procurement Directives, Freedom of Information Act)
Experience
Essential
* Experience supporting large-scale, high-performance, high-availability network architectures
* Experience with complex network architecture designs and updating technology per approved designs
* Experience with network security technologies from Cisco and other vendors in enterprise environments
* Knowledge of infrastructure and security principles, techniques and processes
* Experience as a senior technical contributor, capable of leading and mentoring a team
* Strong time management and ability to plan own activities
* Fluent in English; technical proficiency in network design and hardware terminology
* A Degree in a relevant subject, or equivalent qualifications/5 years+ experience
* Knowledge of ITIL and its implementation in large organisations
Desirable
* Deep knowledge of latest technologies and methodologies for enterprise-wide networking
* Commercial/Financial awareness for strategic problem solving
* Knowledge of agile methodologies (e.g., Scrum)
Advert closes on Sunday 28th September 2025 at 2359
Excellent Benefits include:
* Final salary pension scheme
* Free travel on the TfL network
* Reimbursement of up to 75% of standard class National Rail travel or a 28-day flexi ticket
* 30 days annual leave plus public and bank holidays
* Hybrid working approach aligned to business needs
* Private healthcare discounted scheme (optional)
* Tax-efficient cycle-to-work programme
* Retail, health, leisure and travel offers
* Discounted Eurostar travel
Additional Information
Please apply supplying your CV preferably in ".docx" format. Documents should be A4, in Arial 12 font, and a maximum of 2 pages per document.
If shortlisted you may be invited to a video interview. Interviews/assessments may be organised at short notice; we reserve the right to close the application window early if we receive a high volume of suitable applications.
We are committed to equality, diversity and inclusion. We aim to make recruitment inclusive and are a disability-confident employer, guaranteeing an interview to any disabled candidate who meets all essential criteria. We also use anonymising software to remove identifying information from CVs to ensure fairness.
Many staff work flexibly in various ways. Please discuss your flexibility needs at interview. We welcome applications even if you do not meet all criteria.
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