Senior NSX Engineer (26-00705) -

Senior NSX Engineer

Springfield, VA

$135k-$155k

Marathon TS is seeking an experienced Senior NSX Engineer to design, implement, operate, secure, and troubleshoot VMware NSX-based network virtualization solutions supporting a mission-critical U.S. Department of War environment. Candidates must possess an active Top Secret/SCI (TS/SCI) security clearance with a current CI Polygraph. The ideal candidate brings 5+ years of hands-on VMware NSX engineering experience, strong VMware vSphere and VMware Cloud Foundation (VCF) integration knowledge, and the ability to own the full NSX lifecycle from architecture and deployment through security hardening, automation, upgrades, and Tier 3 incident resolution.

Key Responsibilities

• Design, deploy, configure, operate, and sustain VMware NSX-T / VMware Cloud Foundation Networking across production, development, test, and mission environments.
• Engineer NSX Manager clusters, transport nodes/profiles, transport zones, uplink profiles, VDS/N-VDS networking, and NSX Edge clusters.
• Design and administer overlay and VLAN-backed segments, Tier-0/Tier-1 gateways, distributed routing, BGP, static routing, ECMP, route redistribution, and north-south/east-west connectivity.
• Implement microsegmentation and Zero Trust-aligned controls using Distributed Firewall, Gateway Firewall, security groups, dynamic membership, tags, context profiles, and policy-based security.
• Develop auditable, least-privilege firewall policies in coordination with cybersecurity, ISSO/ISSM, RMF, application, and network teams.
• Integrate NSX with vCenter, vSphere, VCF, vSAN, VMware Aria Operations/Logs, PKI, identity, SIEM, vulnerability-management, and enterprise monitoring platforms.
• Troubleshoot BGP/routing adjacency failures, MTU/TEP/Geneve issues, asymmetric routing, firewall processing, packet loss, performance degradation, and NSX Edge failures.
• Perform packet-level analysis using NSX CLI/nsxcli, vmkping, pktcap-uw, tcpdump-uw, Traceflow, flow monitoring, and distributed firewall analysis.
• Lead NSX upgrades, patching, certificate replacement, migrations, backup/recovery validation, and lifecycle-management activities with formal implementation, test, validation, and backout plans.
• Maintain engineering standards, configuration baselines, diagrams, firewall matrices, runbooks, and as-built documentation; provide Tier 3 escalation support and mentor junior engineers.

Required Qualifications

• Active Top Secret/SCI (TS/SCI) security clearance with current CI Polygraph.
• Bachelor's degree in Information Technology, Computer Science, Engineering, Cybersecurity, or a related discipline; equivalent relevant experience may be substituted.
• 5+ years of hands-on VMware NSX experience in enterprise-scale environments and 5+ years of VMware vSphere experience, including ESXi, vCenter Server, VDS, virtual networking, cluster operations, and troubleshooting.

Advanced NSX-T / VCF Networking expertise

overlay/VLAN segments, Tier-0/Tier-1 gateways, Edge Nodes/clusters, BGP, static routing, ECMP, route redistribution, Distributed Firewall, Gateway Firewall, dynamic groups/tagging, NAT, VPN, DHCP, and lifecycle operations.

Strong enterprise networking fundamentals

TCP/IP, DNS, DHCP, ARP, VLANs, VXLAN/Geneve, MTU, BGP, OSPF, VRFs, link aggregation, firewalling, NAT, load balancing, and network troubleshooting.

• Experience in DoW, federal civilian, intelligence community, or other highly regulated environments with formal change control, security approval, documentation, and audit requirements.
• Working knowledge of RMF, ATO, DISA STIGs, POA&Ms, vulnerability management, security controls, continuous monitoring, and remediation of applicable security findings.
• Strong written and verbal communication skills, including technical diagrams, implementation plans, SOPs, security documentation, and executive-ready status updates.

Required Certifications

Certification requirements should align with the assigned DoW Cyber Workforce Framework / DoD 8140 work role and applicable contract requirements.

• Current CompTIA Security+ CE or another approved DoW 8140-aligned baseline certification appropriate to the assigned work role.
• One current VMware/Broadcom networking, security, or VMware Cloud Foundation certification, such as VCP-NV, VMware Cloud Foundation Administrator, VMware Cloud Foundation Architect, or a comparable current NSX/VCF networking certification.

Preferred Qualifications

• Experience designing or supporting VMware Cloud Foundation, including SDDC Manager, workload domains, lifecycle management, vSphere, and NSX integration.
• Experience integrating NSX with Cisco Nexus, Juniper, Palo Alto Networks, F5, or similar enterprise technologies.
• Experience with VXLAN/Geneve overlays, BGP underlay/overlay routing, multi-rack architectures, and highly available network services.
• Automation / Infrastructure as Code experience using PowerShell/PowerCLI, Ansible, VMware Aria Automation, REST APIs, Git, YAML, and JSON.
• Experience integrating NSX telemetry and logs with Splunk, Elastic, or comparable SIEM/observability platforms.
• Experience with enterprise PKI, certificate lifecycle management, Active Directory, LDAP, identity federation, RBAC, privileged-access management, and MFA.
• Experience supporting classified, disconnected, air-gapped, or tactical-edge environments.
• Familiarity with Dell PowerEdge, Cisco UCS, HPE, DISA STIG Viewer, SCAP scanning, ACAS/Nessus, and POA&M remediation workflows.

Core Technical Competencies

NSX Architecture

NSX Manager clusters, transport zones/nodes, Edge clusters, segments, gateways, and security policies.

Routing

BGP, static routing, ECMP, route redistribution, Tier-0/Tier-1 routing, and physical-network integration.

Network Security

Microsegmentation, Distributed/Gateway Firewall, dynamic groups, tagging, rule analysis, and least-privilege policies.

vSphere Networking

vCenter, ESXi, VDS, VMkernel, vmnic, port groups, cluster networking, and host-level troubleshooting.

Advanced Troubleshooting

Traceflow, NSX CLI, ESXi packet capture, BGP diagnostics, flow analysis, logs, and packet-level troubleshooting.

Operations & Compliance

Upgrades, backup/recovery, certificates, lifecycle management, RMF, STIGs, ATO support, vulnerability remediation, and change control.

Automation & Documentation

PowerCLI, Ansible, REST APIs, Git; diagrams, runbooks, firewall matrices, test plans, validation procedures, and backout plans.

US Citizenship Required

TS/SCI Required

Marathon TS is committed to the development of a creative, diverse and inclusive work environment. In order to provide equal employment and advancement opportunities to all individuals, employment decisions at Marathon TS will be based on merit, qualifications, and abilities. Marathon TS does not discriminate against any person because of race, color, creed, religion, sex, national origin, disability, age or any other characteristic protected by law (referred to as "protected status ").

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