Ingress Lan Port Features - Cisco 7609 Configuration Manual

Understanding How PFC QoS Works
Egress LAN Port Features
PFC QoS supports egress LAN port scheduling and congestion avoidance using Layer 2 CoS values.
Egress LAN port marking sets Layer 2 CoS values and Layer 3 DSCP values. See the
Port Features" section on page
Egress OSM Port Features
Ingress PFC QoS sets Layer 3 DSCP values that can be used by the OSM egress QoS features.
MSFC Features
PFC QoS marks IP traffic transmitted to the MSFC with rewritten Layer 3 DSCP values. With PFC2,
CoS is equal to IP precedence in all traffic sent from the MSFC2 to egress ports; with PFC1, CoS is zero.
Traffic that is Layer 3 switched does not go through the MFSC and retains the CoS value assigned by
Note
the PFC.

Ingress LAN Port Features

These sections describe ingress LAN port PFC QoS features:
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Ingress LAN Port Trust States
The trust state of an ingress LAN port determines how the port marks, schedules, and classifies received
Layer 2 frames, and whether or not congestion avoidance is implemented. You can configure the trust
state of each ingress LAN port as follows:
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See the
PFC QoS implements ingress LAN port congestion avoidance only on LAN ports configured to trust
CoS.
Note Ingress LAN port marking, scheduling, and congestion avoidance use Layer 2 CoS values and does not
use or set Layer 3 IP precedence or DSCP values.
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
32-12
Ingress LAN Port Trust States, page 32-12
Marking at Untrusted Ingress LAN Ports, page 32-13
Marking at Trusted Ingress LAN Ports, page 32-13
Ingress LAN Port Scheduling and Congestion Avoidance, page 32-13
Untrusted (default)
Trust IP precedence (not supported on 1q4t LAN ports except Gigabit Ethernet)
Trust DSCP (not supported on 1q4t LAN ports except Gigabit Ethernet)
Trust CoS (not supported on 1q4t LAN ports except Gigabit Ethernet)
"Configuring the Trust State of Ethernet LAN and OSM Ingress Ports" section on page
32-21.
Chapter 32 Configuring PFC QoS
"LAN Egress
32-53.
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