Junos Class of Service (JCOS)

This two-day course provides students with advanced class-of-service (CoS) knowledge and configuration examples. The course begins with an overview of CoS before going into classification, policing, scheduling, and rewriting. The course then covers class-based forwarding and finishes with a case study.

Through demonstrations and hands-on labs, students will gain experience in configuring and verifying Junos CoS features.

Target audience:

This course benefits individuals responsible for configuring and monitoring devices running the Junos OS, especially those in a service provider environment. It also benefits individuals responsible for designing networks containing devices running the Junos OS.


Students should attend the Introduction to Junos Software (IJS) course, the Junos Routing Essentials (JRE) course, and the Junos Intermediate Routing (JIR) course, or have equivalent experience prior to attending this class. General knowledge of CoS concepts is also helpful.


After successfully completing this course, you should be able to:

  • Understand the history and evolution of CoS.
  • Identify the CoS fields in various packet headers.
  • List the CoS processing stages on devices running the Junos OS.
  • Identify the default CoS settings on devices running the Junos OS.
  • Configure and verify behavior aggregate (BA) and multifield (MF) classification.
  • Configure and verify two-color and tricolor marking policers.
  • Configure and verify schedulers and their components.
  • Configure and verify the multiple levels of hierarchical schedulers.
  • Configure and verify packet header rewriting.
  • Configure and verify class-based forwarding.
  • Create a CoS configuration based on a set of design requirements.

Course contents: 

  • Chapter 1: Course Introduction
  • Chapter 2: CoS Overview
  • Chapter 3: Packet Classification
  • Lab 1: Configuring Packet Classification
  • Chapter 4: Policing
  • Lab 2: Configuring Policers
  • Chapter 5: Scheduling
  • Lab 3: Configuring Schedulers
  • Chapter 6: Hierarchical Scheduling
  • Lab 4: Configuring Hierarchical Schedulers
  • Chapter 7: Rewrite Rules
  • Lab 5: Configuring Rewrite Rules
  • Chapter 8: CoS-Based Forwarding
  • Lab 6: Configuring CBF
  • Chapter 9: Case Study
  • Appendix A: CoS Processing on M Series, T Series, and MX Series Devices



JL2V + JL3V + JCOS + JMR + AJSPR + exam : JNCIP-SP (Juniper Networks Certified Internet Professional Service Provider)



2 days