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Cisco ASR 901 Aggregation Services Router Command Reference Guide
OL-26031-07
Chapter 1 CLI Command Reference
set precedence
set precedence
To set the precedence value in the packet header, use the set precedence command in policy-map class
configuration mode. To remove the precedence value, use the no form of this command.
set precedence {precedence-value}
no set precedence {precedence-value}
Syntax Description
Command Default Disabled
Command Modes Policy-map class configuration
Command History
Usage Guidelines
Command Compatibility
If a router is loaded with an image from this version (that is, Cisco IOS Release 12.2(13)T) that
contained an old configuration, the set ip precedence command is still recognized. However, the set
precedence command will be used in place of the set ip precedence command.
The set precedence command cannot be used with the set dscp command to mark the same packet. The
two values, DSCP and precedence, are mutually exclusive. A packet can be one value or the other, but
not both.
Bit Settings
Once the precedence bits are set, other quality of service (QoS) features such as weighted fair queueing
(WFQ) and Weighted Random Early Detection (WRED) then operate on the bit settings.
Precedence Value
The network gives priority (or some type of expedited handling) to marked traffic through the application
of WFQ or WRED at points downstream in the network. Typically, you set the precedence value at the
edge of the network (or administrative domain); data then is queued according to the specified
precedence. WFQ can speed up handling for certain precedence traffic at congestion points. WRED can
ensure that certain precedence traffic has lower loss rates than other traffic during times of congestion.
The set precedence command cannot be used with the set dscp command to mark the same packet. The
two values, differentiated services code point (DSCP) and precedence, are mutually exclusive. A packet
can have one value or the other, but not both.
precedence-value A number from 0 to 7 that sets the precedence bit in the packet header.
Release Modification
15.1(2)SNG Support for this command was introduced on the Cisco ASR 901 router.
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