52-10
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 52 Configuring QoS
Understanding How QoS Works
QoS Feature Set Summary
The QoS feature set on your switch is determined by the switching engine on the supervisor engine.
Enter the
show module
command for the supervisor engine to display your switching engine
configuration. The display shows the “Sub-Type” to be one of the following:
•
Supervisor Engine 32 (WS-SUP32-GE-3B) with Policy Feature Card 3B (PFC3B/PFC3BXL)
•
Supervisor Engine 720 (WS-SUP720) with PFC3A/PFC3B/PFC3BXL
•
Supervisor Engine 2 (WS-X6K-SUP2-2GE) with Layer 3 Switching Engine II
(WS-F6K-PFC2—Policy Feature Card 2 or PFC2)
•
Supervisor Engine 1 (WS-X6K-SUP1A-2GE or WS-X6K-SUP1-2GE) with one of the following:
–
Layer 3 Switching Engine (WS-F6K-PFC—Policy Feature Card or PFC)
–
Layer 2 Switching Engine II (WS-F6020A)
–
Layer 2 Switching Engine I (WS-F6020)
The Layer 3 Switching Engine (WS-F6K-PFC) and Layer 3 Switching Engine II (WS-F6K-PFC2)
support similar feature sets. The two Layer 2 switching engines support the same QoS feature set.
In addition to the features that are supported by the other two Layer 3 switching engines, PFC3A
supports these features:
•
Egress QoS
•
Egress DSCP mutation
•
Optional egress DSCP rewrite
These sections describe the QoS feature sets:
•
Ethernet Ingress Port Features, page 52-10
•
Layer 3 Switching Engine Features, page 52-10
•
Layer 2 Switching Engine Features, page 52-11
•
Ethernet Egress Port Features, page 52-11
•
Single-Port ATM OC-12 Switching Module Features, page 52-11
•
Multilayer Switch Feature Card (MSFC, MSFC2, or MSFC3), page 52-11
Ethernet Ingress Port Features
With any switching engine, QoS supports classification, marking, scheduling, and congestion avoidance
using the Layer 2 CoS values at the Ethernet ingress ports. Classification, marking, scheduling, and
congestion avoidance at the Ethernet ingress ports do not use or set the Layer 3 IP precedence or DSCP
values. With a Layer 3 switching engine, you can configure the Ethernet ingress port trust states that can
be used by the switching engine to set the Layer 3 IP precedence or DSCP values and the Layer 2 CoS
value. For more information, see the
“Ethernet Ingress Port Marking, Scheduling, Congestion
Avoidance, and Classification” section on page 52-12
.
Layer 3 Switching Engine Features
With PFC3A/PFC3B/PFC3BXL, PFC2, or PFC, QoS supports classification, marking, and policing
using the access control lists (ACLs).