Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Software Configuration Guide, Release 12.2(33)MRB
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Appendix B Cisco MWR 2941 Router Command Reference
set precedence
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.
Using This Command with the Enhanced Packet Marking Feature
If you are using this command as part of the Enhanced Packet Marking feature, you can use this
command to specify the “from-field” packet-marking category to be used for mapping and setting the
precedence value. The “from-field” packet-marking categories are as follows:
• CoS
• QoS group
If you specify a “from-field” category but do not specify the table keyword and the applicable
table-map-name argument, the default action is to copy the value associated with the “from-field”
category as the precedence value. For instance, if you configure the set precedence cos command, the
CoS value is copied and used as the precedence value.
You can do the same for the QoS group-marking category. That is, you can configure the set precedence
qos-group command, and the QoS group value is copied and used as the precedence value.
The valid value range for the precedence value is a number from 0 to 7. The valid value range for the
QoS group is a number from 0 to 99. Therefore, when configuring the set precedence qos-group
command, note the following points:
• If a QoS group value falls within both value ranges (for example, 6), the packet-marking value is
copied and the packets are marked.
• If QoS group value exceeds the precedence range (for example, 10), the packet-marking value is not
copied, and the packet is not marked. No action is taken.
Setting Precedence Values for IPv4 Packets Only
To set the precedence values for IPv4 packets only, use a command involving the ip keyword like the
match ip precedence or match ip dscp command or include the match protocol ip command along
with the others in the class map. Without the additional ip keyword, the class-map may match both IPv6
and IPv4 packets (depending on the other match criteria) and the set precedence or set dscp command
may act upon both types of packets.
Examples The following example shows how to use the set precedence command.
Router(config)# policy-map policy-cos
Router(config-pmap)# class class-default
Router(config-pmap-c)# set precedence 4
Router(config-pmap-c)# end