Cisco 7604 Configuration Manual page 611

Chapter 41 Configuring PFC QoS
Port Trust
In PFC QoS, trust means to accept as valid and use as the basis of the initial
can configure ports as untrusted or you can configure them to trust these QoS values:
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Traffic received through an untrusted port is called untrusted traffic.
Ingress Congestion Avoidance
PFC QoS implements congestion avoidance on
traffic on the basis of its Layer 2 CoS value and assigns it to an ingress queue to provide congestion
avoidance. In Release 12.2(18)SXF5 and later releases, you can configure WS-X6708-10GE
ports
Marking at Trust CoS LAN Ports" section on page 41-18
avoidance.
PFC and DFC QoS Features
These sections describe PFCs and DFCs as they relate to QoS:
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OL-4266-08
Layer 2 CoS
A port configured to trust CoS is called a trust CoS port.
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Traffic received through a trust CoS port or configured by a policy map to trust CoS is called
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trust CoS traffic.
Not all traffic carries a CoS value. Only ISL, 802.1Q, and 802.1P traffic carries a CoS value.
Note
PFC QoS applies the
untrusted ports, PFC QoS applies the port CoS value to all traffic, overwriting any received
CoS value.
IP precedence
A port configured to trust IP precedence is called a trust IP precedence port.
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Traffic received through a trust IP precedence port or configured by a policy map to trust
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IP precedence is called trust IP precedence traffic.
DSCP
A port configured to trust DSCP is called a trust DSCP port.
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Traffic received through a trust DSCP port or configured by a policy map to trust DSCP is called
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trust DSCP traffic.
to use received DSCP values for congestion avoidance. See the
Supported Policy Feature Cards, page 41-10
Supported Distributed Forwarding Cards, page 41-10
PFC and DFC QoS Feature List and Flowchart, page 41-10
Internal DSCP Values, page 41-12
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
port CoS value to any traffic that does not carry a CoS value. On
trust CoS ports. On a trust CoS port, QoS classifies the
for more information about ingress congestion
Understanding How PFC QoS Works
internal DSCP value. You
trust DSCP
"Ingress Classification and
41-9