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Senior/Lead Software Engineer, Packet Forwarding

Arista Networks

Nashua, NH • 9/15/2026

Job Description

Job Description
Company Description

Arista Networks is an industry leader in data-driven, client-to-cloud networking for large data center, campus and routing environments. What sets us apart is our relentless pursuit of innovation. We leverage the latest advancements in cloud computing, artificial intelligence, and software-defined networking to provide our clients with a competitive edge in an increasingly interconnected world. Our solutions are designed to not only meet the current demands of the digital landscape but to also anticipate and adapt to future challenges.

At Arista we value the diversity of thought and perspectives that each employee brings to the table. We believe that fostering an inclusive environment, where individuals from various backgrounds and experiences feel welcome, is essential for driving creativity and innovation.

Our commitment to excellence has earned us several prestigious awards, such as Best Engineering Team, Best Company for Diversity, Compensation, and Work-Life Balance. At Arista, we take pride in our track record of success and strive to maintain the highest standards of quality and performance in everything we do.

Job Description

Who You'll Work With

Arista Networks is looking for world-class Senior/LeadPacketForwardingEngine (PFE)SoftwareEngineers.

As a Senior/Lead PFESoftwareEngineer, you will collaborate and work with customers, product management and engineers to design and build novelpacketforwardingfeatures inEOSthat help networks run effectively and efficiently. You will need to understand thepacketforwardingarchitecture in depth and figure out how to apply it optimally to solve customer problems. You will design thepacketforwardingflow, design data structures and algorithms to render thepacketforwardingstate used by theforwardingengine for efficiency and scale, and tie it all together with the higher layers.

In this role, you will get to confront complex, multi-dimensional problems such as

“Upgradesoftwareon aswitchwith no more than a few milliseconds of downtime”
“Render aroutingtable with >1M routes into theforwardingpath on arouterwith a hundredforwardingchips”

that are open ended, challenging, fun and require strong problem solving skills.

AristaSoftwareEngineering roles demand a strong and broadsoftwareengineering background. While the primary focus area for this role ispacketforwarding, the role will cover all aspects ofsoftwaredevelopment spanning the addition of new features, debugging problems and fine tuning code for scalability and performance. You will own your projects from definition to deployment and customer interactions, and you will be responsible for the quality of everything you deliver.

AristaSoftwareEngineering prides itself on a supportive and growth oriented culture. Over time, as your interests change, coupled with evolving business needs you will have the opportunity toswitchfrompacketforwardingto other areas, if you like.

What You’ll Do

  • Interface with customers and product management to definepacketforwardingfeatures and solutions.
  • Architect, design and manage the development of these features.
  • Develop and maintain features using C,C++andPython, review and contribute to functional and design specifications. Build automated tests and test infrastructure to test the features.
  • Provide technical leadership across features, projects and tools.
  • Work with Customer Support Engineers and customers to analyze, mitigate and fix problems in customer networks.
  • Work with the SystemTestEngineers to analyze problems found in their tests and provide fixes for those problems.
  • Mentor new and junior engineers to bring them up to speed in Arista'ssoftwaredevelopment environment.
Qualifications

  • BS Computer Science/Electrical Engineering/Computer Engineering + 8 years experience, or MS Computer Science/Electrical Engineering/Computer Engineering + 6 years experience, or Ph.D. in Computer Science/Electrical Engineering/Computer Engineering + 3 years experience, or equivalent work experience
  • Expert knowledge of C orC++andPython.
  • Knowledge of UNIX or Linux
  • Understanding of IP networking and/or distributedsystems
  • Experience working withpacketforwardingchips and pipelines is a plus
  • Applied understanding ofsoftwareengineering principles
  • Strong problem solving andsoftwaretroubleshooting skills
  • Ability to design a solution and implement features independently.
  • Ability to work in small teams.

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Additional Information

Arista Networks is an equal opportunity employer. Arista makes all hiring and employment-related decisions in a non-discriminatory manner without regard to race, color, religion, sex, sexual orientation, gender identity, national origin or any other factor determined to be unlawful under applicable federal, state, or law law. All your information will be kept confidential according to EEO guidelines.