F5 Architect

Role Title: Principal F5 Solutions Architect / Technical Design Authority (TDA)
Engagement Type: Contract Senior / Principal Level
Client / Domain: BT Network Engineering (Enterprise / Telecoms Critical Infrastructure)
Role Overview
We are seeking a senior F5 Technical Design Authority (TDA) / Principal Solutions Architect to provide technical governance, architectural leadership, and strategic direction across a mission-critical, large-scale enterprise network estate.
Operating with significant autonomy, you will serve as the formal Design Authority for application delivery, traffic management, and network security architectures. This is not a BAU support or maintenance role; you will govern high-level designs (HLD) and low-level designs (LLD), establish reusable enterprise design patterns, direct complex platform migrations, and ensure resilient, Zero Trust-aligned security architectures across hybrid and multi-datacentre environments.
Key Responsibilities & Design Authority Remit

• Technical Design Authority (TDA): Act as the definitive technical authority for all F5 and Application Delivery Controller (ADC) architectures, approving end-to-end designs and reviewing delivery-team proposals against strategic roadmaps.
  
• Architecture Standards & Governance: Define reference architectures, reusable configuration patterns, and enterprise guardrails while managing architectural risk across critical transformation initiatives.
  
• Complex Migrations & Consolidation: Architect and guide large-scale F5 migrations, OS upgrades, and platform consolidations supporting high-throughput, mission-critical services.
  
• Platform Automation & DevOps: Champion modern NetDevOps workflows by establishing standards for declarative tooling, automated deployment pipelines, and Git-governed infrastructure.
  
• Escalation & Packet-Level Diagnostics: Provide top-tier architectural oversight and hands-on root-cause analysis for high-impact, complex network and application delivery issues.
  
• Stakeholder & Security Alignment: Partner closely with enterprise network engineering, cyber security, and platform delivery teams to embed strict compliance and Zero Trust principles.
  

Required Skills & Technical Expertise

• F5 Core & Architecture:
  
• Deep expertise across F5 BIG-IP architectures (LTM, GTM/DNS, AFM, APM, and Advanced WAF/ASM).
  
• Production track record leading platform consolidations, high-availability multi-DC clustering, and enterprise lifecycle upgrades.
  
• Advanced packet-level troubleshooting (Wireshark, tcpdump, SSL handshake analysis).
  
• Security, Identity & Zero Trust:
  
• Comprehensive design experience with F5 Advanced WAF/ASM and Advanced Firewall Manager (AFM).
  
• Implementation of Layer 4–7 DDoS mitigation and proactive OWASP Top 10 defense strategies.
  
• Identity federation, SAML, SSO, and Multi-Factor Authentication (MFA) within Zero Trust frameworks.
  
• Hardening, firewall policy design, and security compliance inside regulated boundaries.
  
• Automation & Modern Delivery:
  
• Advanced custom iRule development (event-driven traffic inspection, manipulation, and security logic).
  
• API-driven management using iControl REST and declarative toolchains (AS3, DO, FAST).
  
• Infrastructure as Code (Terraform, Ansible) and Git-based CI/CD pipeline automation.
  
• Core Networking & Protocols:
  
• In-depth understanding of TCP/IP, HTTP/HTTPS, SSL/TLS offloading/bridging, DNS, DHCP, and NTP.
  
• Strong foundation in enterprise routing and switching (BGP, OSPF, VLANs, VXLAN) across enterprise WAN and core datacentre networks.
  
• Governance & Environment:
  
• Verifiable experience as an embedded TDA, Lead Architect, or Principal Consultant within regulated industries (Telecoms, Banking, Financial Services, or Critical National Infrastructure).
  

Desirable Skills

• Hands-on architecture or migration experience with NGINX / F5 NGINX Plus for modern microservices or hybrid ingress.
  
• Certified F5 Solution Expert / Certified Technical Specialist (F5-CSE, F5-CTS LTM/ASM/DNS).
  
• Working knowledge of cloud ADC integrations (AWS, Azure, or GCP).
  

The Right Candidate Profile

• Operates effectively as the definitive technical expert in the room, making decisive, defensible architectural calls.
  
• Combines high-level design leadership with the ability to dive into packet-level mechanics when resolving critical design flaws.
  
• Ramps up quickly in complex topologies with sparse legacy documentation, driving measurable architectural clarity from day one.