Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual page 555

Chapter 38 Configuring PFC QoS
The combination of multiple queues and the scheduling algorithms associated with each queue allows the
switch to provide
Figure 38-8
configurations function similarly.
Figure 38-8 Receive Queue Drop Thresholds
Reserved for
CoS 6 and 7
Reserved for
CoS 4 and higher
Reserved for
CoS 2 and higher
Available for
traffic with any
CoS value
100% available for CoS 6 and 7
80% available for CoS 4 and 5
60% available for CoS 2 and 3
50% available for CoS 0 and 1
Ingress Queue Types
To see the queue structure of a LAN port, enter the show queueing interface {ethernet | fastethernet |
gigabitethernet | tengigabitethernet} slot/port | include type command. The command displays one of
the following architectures:
•
•
•
•
•
OL-11439-03
traffic carrying CoS values mapped only to the queue. The switch uses WRED-drop thresholds for
traffic carrying CoS values mapped to the queue and a threshold. All LAN ports of the same type
use the same drop-threshold configuration.
congestion avoidance.
illustrates the drop thresholds for a 1q4t ingress LAN port. Drop thresholds in other
Drop threshold 4: 100%
Drop threshold 3: 80%
Drop threshold 2: 60%
Drop threshold 1: 50%
Receive queue
1q2t indicates one standard queue with one configurable tail-drop threshold and one
nonconfigurable tail-drop threshold.
1q4t indicates one standard queue with four configurable tail-drop thresholds.
1q8t indicates one standard queue with eight configurable tail-drop thresholds.
2q8t indicates two standard queues, each with eight configurable tail-drop thresholds.
8q8t indicates eight standard queues, each with eight thresholds, each configurable as either
WRED-drop or tail-drop.
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
Understanding How PFC QoS Works
Traffic is dropped
(Default values shown)
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