Senior Network Engineer Lorton, VA - On-Site Required TS/SCI The Defense sector at Leidos is seeking an experienced Senior Network Engineer to support a fast-paced Department of Defense (DoD) program supporting the Air Force Life Cycle Management Center (AFLCMC). The position supports the engineering, deployment, modernization, and sustainment of network infrastructure across multiple customer locations. The Senior Network Engineer will serve as a senior technical contributor responsible for translating mission and technical requirements into secure, resilient, and supportable network solutions. They will participate throughout the network engineering lifecycle, including requirements analysis, architecture and design, hardware/software selection, procurement support, staging, implementation, testing, troubleshooting, documentation, and operational transition. The successful candidate will have hands-on experience with enterprise routing, switching, firewalls, WAN technologies, secure communications, and network management in DoD or similarly regulated environments. This position does require the ability to work 100% on-site at our location in Lorton, VA. Primary responsibilities: Develop detailed network architectures and engineering designs aligned with DoD, Air Force, cybersecurity, availability, and mission requirements. Translate operational and technical requirements into network designs, implementation plans, equipment specifications, Bills of Materials (BOMs), and technical documentation. Design, configure, deploy, and troubleshoot enterprise network infrastructure, including routers, Layer 2/Layer 3 switches, firewalls, VPN gateways, and associated network services. Engineer LAN and WAN solutions incorporating technologies such as Ethernet, VLANs, trunking, Spanning Tree Protocol (STP), link aggregation, QoS, access control lists (ACLs), and redundant/high-availability architectures. Configure and troubleshoot routing technologies and protocols such as BGP, OSPF, and static routing in enterprise and multi-site environments. Design and support secure WAN connectivity using technologies such as IPsec, site-to-site VPNs, MPLS, and other DoD-approved transport solutions. Support implementation and troubleshooting of network security technologies, including firewalls, network segmentation, access controls, secure management interfaces, and encrypted communications. Perform packet-level and protocol analysis to identify network performance, connectivity, routing, security, and interoperability issues. Utilize network monitoring and troubleshooting technologies such as SNMPv3, Syslog, ICMP, NetFlow, packet capture, and network management platforms to identify and resolve operational issues. Develop test plans and conduct verification and validation of network solutions to confirm functionality, performance, resiliency, interoperability, and cybersecurity compliance. Conduct pre-deployment staging, configuration validation, and implementation readiness activities prior to installation at customer locations. Troubleshoot complex network issues during deployment, testing, and operational sustainment and perform root-cause analysis when required. Develop and maintain network documentation, including logical and physical network diagrams, IP address plans, configuration baselines, interface documentation, rack elevations, cable diagrams, and as-built documentation. Maintain configuration control and document network changes in accordance with established change and configuration management processes. Support DoD cybersecurity requirements, including applicable Security Technical Implementation Guides (STIGs), security controls, vulnerability remediation, and Risk Management Framework (RMF) activities. Collaborate with cybersecurity engineers to ensure network infrastructure meets applicable DoD security and Zero Trust requirements. Provide technical leadership and guidance to junior engineers and field personnel during network installation, integration, troubleshooting, and operational turnover. Support technical reviews, engineering meetings, site surveys, deployment planning, and customer technical discussions. Provide technical input to procurement activities and evaluate network hardware/software against technical, security, interoperability, lifecycle, and mission requirements. Maintain awareness of emerging network, cybersecurity, cloud, automation, and DoD enterprise networking technologies and recommend improvements where appropriate. Basic Qualifications: US Citizen with an active Top Secret clearance with the ability to obtain and main a SCI prior to your start date. Bachelor's degree with 8+ years of experience or a Master’s degree with 6+ years of experience. Additional experience may be considered in lieu of a degree. Demonstrated experience designing, implementing, configuring, and troubleshooting enterprise network infrastructure. Strong understanding of the OSI and TCP/IP models and network protocols associated with Layers 1–4. Hands-on experience configuring enterprise routers and switches. Experience implementing and troubleshooting LAN technologies, including VLANs, 802.1Q trunking, STP/RSTP, link aggregation, and Layer 3 switching. Experience with IP addressing, subnetting, route selection, access control lists, and network segmentation. Working knowledge of dynamic routing protocols such as BGP and OSPF. Experience designing, deploying, or supporting WAN connectivity across geographically separated locations. Experience implementing or supporting IPsec/site-to-site VPN technologies. Experience using network monitoring and troubleshooting technologies such as ICMP, SNMPv3, Syslog, packet captures, and network management platforms. Experience troubleshooting complex network connectivity, routing, performance, and configuration issues. Ability to develop and maintain detailed technical documentation and network diagrams. Understanding of network security principles, secure management practices, segmentation, encryption, and defense-in-depth. Strong analytical, troubleshooting, written communication, and technical documentation skills. Preferred Qualifications: US Citizen with an active TS/SCI security clearance. Experience supporting Department of Defense, U.S. Air Force, Intelligence Community, or other highly regulated government environments. Experience with Cisco and/or Juniper enterprise routing and switching platforms. Experience with next-generation firewall technologies such as Cisco, Palo Alto Networks, Fortinet, or equivalent enterprise platforms. Experience designing or supporting high-availability network architectures, redundant WAN connectivity, and resilient network services. Experience with DoD STIGs, RMF, NIST security controls, vulnerability management, and configuration compliance. Understanding of DoD Zero Trust principles, including network segmentation, identity-aware access, least privilege, continuous monitoring, and secure access architectures. Experience with secure communications and operation or integration of DoD cryptographic devices, such as TACLANE or equivalent Type 1 encryption technologies. Experience with Cisco Secure Client/AnyConnect, Azure VPN Gateway, MPLS, IPsec, GRE, or similar enterprise WAN/VPN technologies. Working knowledge of cloud networking, particularly Microsoft Azure, including VNets, subnets, Network Security Groups (NSGs), routing, VPN gateways, and hybrid connectivity. Familiarity with network automation and Infrastructure as Code technologies such as Python, Ansible, Terraform, REST APIs, or similar tools. Experience with network monitoring and performance-management platforms such as SolarWinds, Cisco network management platforms, Splunk, or equivalent technologies. Demonstrated experience leading technical activities or mentoring junior network engineers. Relevant industry certifications such as CCNP Enterprise, CCNP Security, CCIE, JNCIP/JNCIE, PCNSE, AZ-700, Security+, CISSP, or equivalent certifications. DABAOPP1 If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo — because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 — and moving faster than anyone else dares. Original Posting: October 20, 2026 For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above. Pay Range: Pay Range $107,900.00 - $195,050.00 The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law. Leidos Leidos is an industry and technology leader serving government and commercial customers with smarter, more efficient digital and mission innovations. Headquartered in Reston, Virginia, with 47,000 global employees, Leidos reported annual revenues of approximately $17.2 billion for the fiscal year ended January 2, 2026. For more information, visit www.Leidos.com. Pay and Benefits Pay and benefits are fundamental to any career decision. That's why we craft compensation packages that reflect the importance of the work we do for our customers. Employment benefits include competitive compensation, Health and Wellness programs, Income Protection, Paid Leave and Retirement. More details are available here. Securing Your Data Leidos will never ask you to provide payment-related information at any part of the employment application process. And Leidos will communicate with you only through emails that are sent from a Leidos.com email address. If you receive an email purporting to be from Leidos that asks for payment-related information or any other personal information, please report the email to spam.leidos@leidos.com. Commitment and Diversity All qualified applicants will receive consideration for employment without regard to sex, race, ethnicity, age, national origin, citizenship, religion, physical or mental disability, medical condition, genetic information, pregnancy, family structure, marital status, ancestry, domestic partner status, sexual orientation, gender identity or expression, veteran or military status, or any other basis prohibited by law. Leidos will also consider for employment qualified applicants with criminal histories consistent with relevant laws.

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