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

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Chapter 1
Quality of Service Overview
The quality of service (QoS) feature enables your E Series router to distinguish traffic
with strict timing requirements from traffic that can tolerate delay, jitter, and loss.
QoS topics are discussed in the following sections:
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QoS on the E Series Router Overview on page 3
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QoS Audience on page 4
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QoS Platform Considerations on page 4
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QoS Terms on page 5
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QoS Features on page 7
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Configuring QoS on the E Series Router on page 8
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QoS References on page 9
QoS on the E Series Router Overview
QoS is a suite of features that configure queuing and scheduling on the forwarding
path of the Juniper Networks E Series Broadband Services Routers. QoS provides a
level of predictability and control beyond the best-effort delivery that the router
provides by default. Best-effort service provides packet transmission with no assurance
of reliability, delay, jitter, or throughput.
QoS as developed for E Series routers conforms to the IETF Differentiated Services
(DiffServ) model (RFCs 2597 and 2598). DiffServ networks classify packets into one
of a small number of aggregated flows or traffic classes for which you can configure
different QoS characteristics. The Juniper Networks QoS architecture extends DiffServ
to support edge features such as high-density queuing.
The E Series router supports:
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IETF architecture for differentiated services
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Assured forwarding per-hop-behavior (PHB) groups
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Expedited forwarding PHB groups
The router supports configurable queuing and scheduling. It has an application-specific
integrated circuit (ASIC) scheduler that supports thousands of queues in a hierarchical
round-robin (HRR) scheduler. The scheduler allows the router to allocate separate
QoS on the E Series Router Overview
■ 3