Cisco 6500 Series Software Configuration Manual page 400

Understanding How PFC QoS Works
Figure 31-7 Egress WAN Port Marking
From PFC2 or
Figure 31-8 Egress LAN Port Scheduling, Congestion Avoidance, and Marking
From switching
engine or MSFC
Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
31-10
MSFC2
Ethernet egress port scheduling, congestion avoidance, and marking
Drop thresholds
OSM switching module marking
Write ToS
Yes
IP traffic
byte into
from PFC?
packet
No
OSM
QoS
Features
Transmit
OSM traffic
Yes
IP traffic
from PFC?
No
Yes
ISL or
802.1Q?
No
Transmit
frame
Chapter 31 Configuring PFC QoS
PFC3
only
DSCP Write ToS
Yes
rewrite byte into
enabled? packet
No
Write CoS
into
frame
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