Juniper JUNOSE 11.1.X - QUALITY OF SERVICE CONFIGURATION GUIDE 3-21-2010, Руководство по настройке

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Chapter 2
Defining Service Levels with Traffic
Classes and Traffic-Class Groups
This chapter provides information for configuring traffic classes and traffic-class
groups on the E Series router.
QoS topics are discussed in the following sections:
■
Traffic Class and Traffic-Class Groups Overview on page 13
■
Configuring Traffic Classes That Define Service Levels on page 14
■
Configuring Traffic-Class Groups That Define Service Levels on page 15
■
Monitoring Traffic Classes and Traffic-Class Groups for Defined Levels of
Service on page 16
Traffic Class and Traffic-Class Groups Overview
A traffic class is a systemwide collection of buffers, queues, and bandwidth that you
can allocate to provide a defined level of service to packets in the traffic class.
A traffic class corresponds to what the IETF DiffServ working group calls a traffic
class in RFC 2597—Assured Forwarding PHB Group (June 1999).
Traffic classes are global to the router. Packets are:
■
Classified into a traffic class on ingress or egress by input policies
■
Queued on fabric queues that are specific to the traffic class
■
Queued on the egress line module on queues that are specific to the traffic class
■
Scheduled for transmission by the scheduler
Best-Effort Forwarding
The router has a default traffic class called best-effort. You cannot delete this class.
You can add the best-effort class to a traffic-class group. The router assigns packets
to the best-effort class in each of the following cases:
■
You do not create any other traffic classes.
■
Packets are not classified into a traffic class.
Traffic Class and Traffic-Class Groups Overview
■ 13