Configuring Qos; Information About Qos - Cisco AP775A - Nexus Converged Network Switch 5010 Configuration Manual

Configuring QoS

This chapter describes how to configure quality of service (QoS) on Cisco Nexus 5000 Series switches. It
contains the following sections:
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Information About QoS

The configurable Cisco NX-OS QoS features on the Cisco Nexus 5000 Series switch allow you to classify
the network traffic, police and prioritize the traffic flow, and provide congestion avoidance.
The default QoS configuration on the switch provides lossless service for Fibre Channel and Fibre Channel
Over Ethernet (FCoE) traffic and best-effort service for Ethernet traffic. QoS can be configured to provide
additional classes of service for Ethernet traffic. Cisco Nexus 5000 Series QoS features are configured using
Cisco Modular QoS CLI (MQC).
Standard Ethernet is a best-effort medium which means that it lacks any form of flow control. In the event
Note
of congestion or collisions, Ethernet will drop packets. The higher level protocols detect the missing data
and retransmit the dropped packets.
Fibre Channel requires a reliable transport system that guarantees the delivery of every packet. To properly
support FCoE, Ethernet has been enhanced with a priority flow control (PFC) mechanism to prevent
congestion.
OL-16597-01
Information About QoS, page 421
QoS Configuration Guidelines and Limitations, page 429
Configuring System Classes, page 429
Configuring QoS on Interfaces, page 445
Configuring Priority Flow Control and Link-Level Flow Control, page 447
Verifying QoS Configuration, page 448
Example QoS Configurations, page 454
C H A P T E R
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
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