Cisco 7604 Configuration Manual page 616

Understanding How PFC QoS Works
Flowchart of PFC QoS Egress LAN Port Features
Figure 41-7
Figure 41-7 Egress LAN Port Scheduling, Congestion Avoidance, and Marking
PFC or MSFC
Egress CoS Values
For all egress traffic, PFC QoS uses a configurable map to derive a CoS value from the final
DSCP
for use in classification and congestion avoidance and to be written into ISL and 802.1Q frames.
With Release 12.2(18)SXF5 and later releases, you can configure WS-X6708-10GE ports to use the final
Note
internal DSCP value for egress LAN port classification and congestion avoidance (see the
DSCP-Based Queue Mapping" section on page
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
41-14
shows how traffic flows through the QoS features on egress LAN ports.
From
Egress queues and
drop thresholds
value associated with the traffic. PFC QoS sends the derived CoS value to the egress LAN ports
PFC3
only
DSCP
Yes
IP traffic
rewrite
from PFC?
enabled?
No
No
Write CoS
Yes
ISL or
into
802.1Q?
frame
No
Transmit
frame
41-100).
Chapter 41 Configuring PFC QoS
Write ToS
Yes
byte into
packet
internal
"Configuring
OL-4266-08