Sr. Tier III O&M Engineer

COMFORT SYSTEMS; Chantilly (VA); On-site; USD 92,000 - 167,000; Full time

Job summary

Leidos, in the Digital Modernization Sector, seeks a Sr. Tier III O&M engineer to support WAN and LAN networks, providing incident resolution, routing and firewall changes, and SME guidance on network technologies.

You will collaborate across teams to maintain optimal network performance and security, including after-hours on-call when needed. The role requires DoD security credentials, extensive experience with OSPF/BGP, and COMSEC awareness, with a focus on open systems architectures and

Qualifications

• TS SCI with a Poly
• 16 years of experience equivalent (Doctorate+8, Master+10, etc.)
• DoD 8570 IAT Level 2 compliance
• Experience configuring boundary protection technologies
• Experience with OSPF, BGP, VPNs, VRF, MPLS
• Service Now or equivalent ITSM familiarity
• Strong communication skills
• MS Office proficiency

Responsibilities

• Support operations and maintenance of LAN/WAN networks
• Monitor network performance
• Configure hardware, networking software and OS
• Assess impact of user requests on performance
• Perform tier 3 troubleshooting and root-cause analysis
• Develop troubleshooting procedures for restoration
• Provide fault and performance management
• Respond to network incidents and resolve issues
• Generate reports and input data for network management
• Coordinate with CM and implementation teams
• Analyze network characteristics and suggest procurements
• Optimize topologies and site configurations
• Document current site configurations and user requirements
• Maintain systems and software
• Ensure open systems compliance (IEEE OSE references)
• May perform COMSEC responsibilities up to 10%
• On-call after-hours support

Skills

Verbal & written communication

MS Office suite

Network engineering concepts

Tools

Palo Alto

Cisco ASA

Forcepoint

Juniper routers

Cisco switches

Job description

Description

The Digital Modernization Sector at Leidos is seeking a Sr. Tier III operations and maintenance (O&M) engineer to support various WAN and LAN networks. Will provide incident resolution, routing changes, firewall changes; act as subject matter expert in WAN and LAN technologies; support intra- and inter- net and other data communications systems or segments of networked system.

Description of Job Duties/Responsibilities:

• Support operations and maintenance activities and administer networks including LAN and WAN technologies such as OSPF, BGP, VRF’s, VLAN’s, VRRP, MPLS.
• Monitor the performance of systems and networks
• Configure, and test hardware, networking software and operating system software
• Review user requests for upgrades or additions to the network to assess impact on network performance and provide advice and guidance on the most practical technical approach to meeting user requirements
• Perform long term O&M activities to include tier 3 troubleshooting and problem resolution
• Prepare troubleshooting procedures for restoring the network to optimal performance levels
• Provide fault management for the network and supports performance management functions
• Respond, isolate, and resolve network troubles
• Execute reporting functions and data input associated with network management
• Coordinate with configuration management and implementation teams
• Analyze network characteristics (e.g., traffic, connect time, transmission speeds, packet sizes, and throughput); recommend procurement, removals, and modifications to network components
• Optimize network topologies and site configurations.
• Coordinate requirements with users
• Assess and document current site network configuration and user requirements
• Maintain operating systems, communications software, data base packages, compilers, assemblers, and utility programs
• Apply software, hardware, and standards information technology skills in the analysis, specification, development, integration, and acquisition of open systems for Information Management (IM) applications
• Ensure these systems and applications are compliant with standards for open systems architectures, reference models, and profiles of standards - such as the IEEE Open Systems Environment (OSE) reference model - as they apply to the implementation and specification of IM solutions on the application platform, across the application program interface (API), and the external environment/software application
• May have up to 10% COMSEC responsibilities, as needed.
• Subject to be called in during afterhours for incident resolution.

Requirements

• TS SCI with a Poly
• Candidate must have 16 years of experience that can be a combination of work history and education. This equates to a Doctorate and 8 years, master’s and 10 years, bachelor’s and 12 years, associates and 14 years or HS diploma and 16 years.
• Must comply with DoD 8570 Information Assurance Technical (IAT) Level 2.
• Experience in configuring and troubleshooting boundary protection technologies such as Palo Alto, Cisco ASA, and Forcepoint appliances
• Experience with configuring and troubleshooting Juniper and Cisco routers and switches.
• Experience with protocols such as OSPF, BGP, VPN’s, VRF’s, MPLS.
• Working knowledge of boundary protection best practices
• Understanding of routing, switching, Internet Protocol (IP) subnet, Network Address Translation (NAT) and security technologies
• Demonstrated ability to engineer and modify rulesets to allow connectivity for new customer requirements
• Demonstrated ability to read, understand, and develop schematic diagrams, technical manuals, and documentation such that the supported equipment and software can be maintained with minimal training
• Working knowledge of Service Now or similar IT Service Management (ITSM) products
• Superior verbal and written communication skills
• Intermediate-level knowledge of MS Office products Word, Excel, PowerPoint, and Visio

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:

August 26, 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 $92,300.00 - $166,850.00

The Leidos pay range for this job level is a general guideline onlyand 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.

About 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 $16.7 billion for the fiscal year ended January 3, 2025. 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 at www.leidos.com/careers/pay-benefits .

Commitment to Non-Discrimination

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.

All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability or veteran status. Leidos will consider qualified applicants with criminal histories for employment in accordance with relevant Laws. Leidos is an equal opportunity employer/disability/vet.