Juniper MX Series, 2nd Edition

Chapter 5. Trio Class of Service

This chapter explores the vast and wonderful world of Class of Service (CoS) on Trio-based PFEs. A significant portion of the chapter is devoted to its highly scalable hierarchical CoS (H-CoS) capabilities.

Readers that are new to general IP CoS processing in Junos or who desire a review of IP Differentiated Services (DiffServ) concepts should consult the Juniper Enterprise Routing book. CoS is a complicated subject, and the intent is to cover new, Trio-specific CoS capabilities without dedicating invaluable space to material that is available elsewhere.

The CoS topics in this chapter include:

• MX router CoS capabilities

• Trio CoS flow

• Hierarchical CoS

• Trio scheduling, priority handling, and load balancing

• MX CoS defaults

• Policy-map feature

• Ingress-queuing

• Per-VLAN queueing for non-Q MPC

• Predicting queue throughput

• Per-unit scheduling CoS lab

• Hierarchical CoS lab

MX CoS Capabilities

This section provides an overview of Trio-based MX router CoS capabilities and operation, which includes a packet walkthrough that illustrates how CoS is provided to transit traffic in the Trio architecture.

The Trio chipset offers several CoS differentiators that should be kept in mind when designing your network’s CoS architecture.

Intelligent Class-Aware Hierarchical Rate Limiters

This feature lets Trio PFEs honor user configured rate limit (shaping) policies for multiple classes of traffic, while at the same time protecting conforming high-priority traffic from ...