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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
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Chapter 31 Configuring PFC QoS
Understanding How PFC QoS Works
QoS selects network traffic (both unicast and multicast), prioritizes it according to its relative
importance, and uses congestion avoidance to provide priority-indexed treatment; QoS can also limit the
bandwidth used by network traffic. QoS makes network performance more predictable and bandwidth
utilization more effective.
Note On the Catalyst 6500 series switches, queue architecture and QoS queueing features such as
Weighted-Round Robin (WRR) and Weighted Random Early Detection (WRED) are implemented with
a fixed configuration in Application Specific Integrated Circuits (ASICs). The queueing architecture
cannot be reconfigured. For more information, see the “Receive Queues” section on page 31-13 and the
“Transmit Queues” section on page 31-21.
These sections describe PFC QoS:
Hardware Supported by PFC QoS, page 31-2
QoS Terminology, page 31-3
PFC QoS Feature Flowcharts, page 31-6
PFC QoS Feature Summary, page 31-11
Ingress LAN Port Features, page 31-12
PFC Marking and Policing, page 31-16
LAN Egress Port Features, page 31-21
PFC QoS Statistics Data Export, page 31-24
Hardware Supported by PFC QoS
With Release 12.1(11a)E and later, PFC QoS supports both LAN ports and optical services module
(OSM) ports:
LAN ports are Ethernet ports on Ethernet switching modules, except for the 4-port Gigabit Ethernet
WAN (GBIC) module (OSM-4GE-WAN). Except for the OSM-4GE-WAN module, OSMs have four
Ethernet LAN ports in addition to WAN ports. With earlier releases, PFC QoS supports only LAN
ports.
OSM ports are the WAN ports on OSMs. The PFC provides ingress QoS for traffic from OSM ports.
For more information, see the following sections:
“Ingress OSM Port Features” section on page 31-11
“Egress OSM Port Features” section on page 31-12
“PFC Marking and Policing” section on page 31-16
“Attaching Policy Maps” section on page 31-21
“Configuring the Trust State of Ethernet LAN and OSM Ingress Ports” section on page 31-53
Refer to the following publication for information about additional OSM QoS features:
http://www.cisco.com/univercd/cc/td/doc/product/core/cis7600/cfgnotes/osm_inst/index.htm