Qos Statistics Data Export - Cisco WS-C6506 Software Manual

Chapter 52 Configuring QoS
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For the port types with a strict-priority queue, the switch services the traffic in the strict-priority transmit
queue before servicing the standard queues. When the switch is servicing a standard queue, after
transmitting a packet, it checks for the traffic in the strict-priority queue. If the switch detects the traffic
in the strict-priority queue, it suspends its service of the standard queue and completes the service of all
the traffic in the strict-priority queue before returning to the standard queue.
Scheduling and Congestion Avoidance
QoS implements the CoS-value-based transmit-queue drop thresholds to avoid congestion in the
transmitted traffic. See the
CoS-to-threshold mapping.
For some port types, you can configure each standard transmit queue to use both a nonconfigurable
100-percent tail-drop threshold and a configurable WRED-drop threshold (see the
Queues" section on page 52-70
page
mapped only to a queue. The switch uses the WRED-drop thresholds for the traffic carrying the CoS
values that are mapped to a queue and a threshold.
Marking
When the traffic is transmitted from the switch, QoS writes the ToS byte into the IP traffic (Layer 3
switching engine only) and the CoS value that was used for scheduling and congestion avoidance into
the ISL or 802.1Q traffic (for more information, see the
Values" section on page

QoS Statistics Data Export

QoS statistics data export generates per-port and per-aggregate policer utilization information and
forwards this information in the UDP packets to traffic monitoring, planning, or accounting applications.
You can enable QoS statistics data export per port or per aggregate policer. The statistics data that is
generated per port consists of the counts of the input and output packets and bytes. The aggregate policer
statistics consists of the counts of the allowed packets and the counts of the packets exceeding the
policed rate.
The QoS statistics data collection occurs periodically at a fixed interval, but the interval at which the
data is exported is configurable. QoS statistics collection is enabled by default, and data export is
disabled by default for all the ports and all the aggregate policers that are configured on the
Catalyst 6500 series switch.
OL-8978-04
tx-(1p3q8t) indicates one strict-priority queue and three standard queues, each with eight
configurable WRED-drop thresholds (on the 1p3q8t ports, each standard queue also has one
nonconfigurable tail-drop threshold).
tx-(1p7q8t) indicates one strict-priority queue and seven standard queues, each with eight
configurable WRED-drop thresholds (on the 1p7q8t ports, each standard queue also has one
nonconfigurable tail-drop threshold).
"QoS Default Configuration" section on page 52-30
52-72). The switch uses the tail-drop thresholds for the traffic carrying the CoS values that are
52-27).
and the "1p2q1t, 1p3q8t, and 1p7q8t Transmit Queues" section on
"Final Layer 3 Switching Engine CoS and ToS
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
Understanding How QoS Works
for the default
"1p3q1t Transmit
52-29