Cisco WS-X6066-SLB-APC - Content Switching Module Software Manual page 715

Chapter 41 Configuring QoS
Ethernet Ingress Port Features
With any switching engine, QoS supports classification, marking, scheduling, and congestion avoidance
using Layer 2 CoS values at Ethernet ingress ports. Classification, marking, scheduling, and congestion
avoidance at Ethernet ingress ports do not use or set Layer 3 IP precedence or DSCP values. With a
Layer 3 switching engine, you can configure Ethernet ingress port trust states that can be used by the
switching engine to set Layer 3 IP precedence or DSCP values and the Layer 2 CoS value. For more
information, see the
Classification" section on page
Layer 3 Switching Engine Features
With a Layer 3 switching engine, QoS supports classification, marking, and policing using IP, IPX, and
Media Access Control (MAC) access control lists (ACLs). ACLs contain access control entries (ACEs)
that specify Layer 2, 3, and 4 classification criteria, a marking rule, and policing rules. Marking sets the
Layer 3 IP precedence or DSCP values and the Layer 2 CoS value to either received or configured
Layer 2 or Layer 3 values. Policing uses bandwidth limits to either drop or mark nonconforming traffic.
For more information, see the
section on page
During processing, a Layer 3 switching engine associates a DSCP value with all traffic, including non-IP
traffic (for more information, see the
Layer 2 Switching Engine Features
With a Layer 2 Switching Engine, QoS can classify traffic using Layer 2 destination MAC addresses,
VLANs, and marking using Layer 2 CoS values. Classification and marking with a Layer 2 Switching
Engine do not use or set Layer 3 IP precedence or DSCP values. For more information, see the
"Classification and Marking with a Layer 2 Switching Engine" section on page
Ethernet Egress Port Features
With any switching engine, QoS supports Ethernet egress port scheduling and congestion avoidance
using Layer 2 CoS values. Ethernet egress port marking sets Layer 2 CoS values and, with a Layer 3
switching engine, Layer 3 DSCP values. For more information, see the
Scheduling, Congestion Avoidance, and Marking" section on page
Single-Port ATM OC-12 Switching Module Features
The ingress interface from a single-port ATM OC-12 switching module is untrusted, and QoS sets CoS
to zero in all traffic received from it. With a Layer 3 switching engine, QoS can mark IP traffic
transmitted to a single-port ATM OC-12 switching module with Layer 3 DSCP values.
Multilayer Switch Feature Card (MSFC or MSFC2)
QoS marks IP traffic transmitted to an MSFC with Layer 3 DSCP values. CoS is zero in all traffic sent
from an MSFC to egress ports.
Traffic that is Layer 3 switched does not go through the MFSC and retains the CoS value assigned
Note
by the Layer 3 switching engine.
78-13315-02
"Ethernet Ingress Port Marking, Scheduling, Congestion Avoidance, and
41-10.
"Classification, Marking, and Policing with a Layer 3 Switching Engine"
41-14.
"Internal DSCP Values" section on page
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
Understanding How QoS Works
41-15).
41-24.
"Ethernet Egress Port
41-24.
41-9