Chapter 1
Quality of Service Overview
random-detect basis Command
Cisco IOS Release: Release 12.0(17)SL
Description: The random-detect basis command was introduced on the PRE1 with the dscp-based and
prec-based options to enable a weighted random early detection (WRED) drop policy based on a DSCP
value or IP precedence level.
Cisco IOS Release: Release 12.2(16)BX
Description: This command was introduced on the PRE2.
Cisco IOS Release: Release 12.3(7)XI
Description: This command was enhanced to enable a drop policy based on a discard-class value. The
discard-class-based option is available only on the PRE2 for Cisco IOS Release 12.3XI images.
Cisco IOS Release: Release 12.2(28)SB
Description: This command was integrated in Cisco IOS Release 12.2(28)SB with the dscp-based,
prec-based, and discard-class-based options.
Cisco IOS Release: Release 12.2(31)SB2
Description: This command was introduced on the PRE3 with the dscp-based, prec-based, and
discard-class-based options.
Cisco IOS Release: Release 12.2(33)SB
Description: This command was enhanced to include the atm-clp-based option and implemented on the
PRE2, PRE3, and PRE4.
show pxf cpu queue interface summary
Cisco IOS Release: Release 12.2(33)SB
Description: The show pxf cpu queue interface summary command was modified to display only the
physical interface and the number of logical links, and implemented on the PRE3 and PRE4. The output
of the command no longer displays the number of priority queues, class queues and so on.
Tail Drop Feature
Cisco IOS Release: Release 12.0(17)SL
Description: The tail drop feature was introduced on the PRE1 to allow you to manage congestion of a
queue. When a queue reaches its configured queue limit, tail drop activates and drops packets. Tail drop
continues to drop packets until the queue is no longer full. Tail drop is the default mechanism used to
control congestion.
Cisco IOS Release: Release 12.2(16)BX
Description: This feature was introduced on the PRE2.
Cisco IOS Release: Release 12.2(28)SB
Description: This feature was integrated in Cisco IOS Release 12.2(28)SB.
OL-7433-09
Cisco 10000 Series Router Quality of Service Configuration Guide
QoS Features, Commands, and Changes
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