Understanding How Pfc Qos Works; Overview - Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual

Understanding How PFC QoS Works

Understanding How PFC QoS Works
The term "PFC QoS" refers to QoS on the Catalyst 6500 series switch. PFC QoS is implemented on
various switch components in addition to the PFC3B. These sections describe how PFC QoS works:
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The PFC3B does not provide QoS for FlexWAN module ports. Refer to this publication for information
Note
about FlexWAN module QoS features:
http://www.cisco.com/en/US/docs/routers/7600/install_config/flexwan_config/flexwan-config-guide.ht
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Overview

Typically, networks operate on a best-effort delivery basis, which means that all traffic has equal priority
and an equal chance of being delivered in a timely manner. When congestion occurs, all traffic has an
equal chance of being dropped.
QoS makes network performance more predictable and bandwidth utilization more effective. QoS
selects (classifies) network traffic, uses or assigns
comply with the configured resource usage limits (polices the traffic and marks the traffic), and provides
congestion avoidance
PFC QoS classification, policing, marking, and congestion avoidance is implemented in hardware on the
PFC3B and in LAN switching module port Application Specific Integrated Circuits (ASICs).
Note Catalyst 6500 series switches do not support all of the MQC features (for example, Committed Access
Rate (CAR)) for traffic that is Layer 3 switched or Layer 2 switched in hardware. Because queuing is
implemented in the port ASICs, Catalyst 6500 series switches do not support MQC-configured queuing.
Figure 38-1
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
38-2
Overview, page 38-2
Component Overview, page 38-5
Understanding Classification and Marking, page 38-14
Understanding Port-Based Queue Types, page 38-19
where resource contention exists.
shows an overview of QoS processing in a Catalyst 6500 series switch.
Chapter 38
QoS labels to indicate priority, makes the packets
Configuring PFC QoS
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