Senior Network Engineer

Falls Church, VA ACI fabric, F5 pairs, and a data center that has to move without anyone noticing. Sienna Systems is seeking a Senior Network Engineer to join our U.S. Customs and Border Protection Enterprise Network Architecture & Engineering Services Support (ENAESS) team, in Ashburn, Virginia. This is the senior technical seat on the data center side: Cisco Application Centric Infrastructure fabric, F5 load balancing, Firepower firewalls, NetScout and IXIA instrumentation, and the circuits and DMZ architecture tying it together. You will own design decisions, not execute someone else's, and there is active migration and colocation work in front of the team. Hybrid out of Ashburn with approximately 35% travel to data center and field locations. Why You'll Want This Role: $137,500 – $142,500 based on experience $10,000 signing bonus for candidates with an active CBP background investigation, payable after 60 days Design authority over an ACI fabric at federal scale Migration and colocation work rather than a steady-state ticket queue Established DHS program with a long runway and a stable government customer 401(k) with 4% matching, immediate vesting, no restrictions 3 weeks Paid Time Off plus 11 Federal Holidays Hybrid out of Ashburn, Virginia Key Responsibilities: Engineer, design, test, and implement network solutions across on-premises and cloud environments to meet functional and technical requirements. Own and extend the Cisco Application Centric Infrastructure fabric. Design, implement, and tune load balancing across F5 Local Traffic Manager and Global Traffic Manager. Lead colocation implementation, data center migration, and equipment relocation activities. Develop design documentation — system design documents, topology diagrams, configurations — and drive it through peer review and security approval before implementation. Coordinate change requests with stakeholders and follow change management procedures to minimize operational impact. Conduct testing of networking hardware, software, configurations, and tools; remediate bugs and vulnerabilities; validate clean integration. Manage software and firmware upgrades and patching, automating where possible and scheduling to minimize disruption. Provide Tier 3 escalation support for network and mission-critical application outages, including corrective action planning and write-ups. Partner with security and operations teams on monitoring, network taps, and traffic visibility.