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, RAPID).

- 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.

📌 Architect (India)
🏢 Selesca
📍 India