Network operatiNg SyStem evolutioN Juniper Networks JUNOS Software: Architectural Choices at the Forefront of Networking

Executive Summary This paper discusses the requirements and challenges inherent in the design of a carrier-class network operating system (OS). Key facets of Juniper Networks ® JUNOS ® Software, Juniper's network operating system, are used to illustrate the evolution of OS design and underscore the relationship between functionality and architectural decisions. The challenge of designing a contemporary network operating system is examined from different angles, including flexibility, ability to power a wide range of platforms, nonstop operation, and parallelism. Architectural challenges, trade-offs and opportunities are identified, as well as some of the best practices in building state-of-the-art network operating systems.