CLI Reference Guide-R01

Chapter 22 | Class of Service Commands
Priority Commands (Layer 3 and 4)
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Command Mode
Interface Configuration (Port, Static Aggregation)
Command Usage
◆ Enter a value pair for the internal per-hop behavior and drop precedence,
followed by the keyword “from” and then up to eight DSCP values separated by
spaces.
◆ This map is only used when the QoS mapping mode is set to “DSCP” by the qos
map trust-mode command, and the ingress packet type is IPv4.
◆ Two QoS domains can have different DSCP definitions, so the DSCP-to-PHB/
Drop Precedence mutation map can be used to modify one set of DSCP values
to match the definition of another domain. The mutation map should be
applied at the receiving port (ingress mutation) at the boundary of a QoS
administrative domain.
◆ The specified mapping applies to all interfaces.
Example
This example changes the priority for all packets entering port 1 which contain a
DSCP value of 1 to a per-hop behavior of 3 and a drop precedence of 1. Referring to
Table 120, note that the DSCP value for these packets is now set to 25 (3x2
3
+1) and
passed on to the egress interface.
Console(config)#interface ethernet 1/5
Console(config-if)#qos map dscp-mutation 3 1 from 1
Console(config-if)#
qos map ip-prec-dscp This command maps IP precedence values in incoming packets to per-hop
behavior and drop precedence values for priority processing. Use the no form to
restore the default settings.
Syntax
qos map ip-prec-dscp phb0 drop-precedence0 ... phb7 drop-precedence7
no map ip-prec-dscp
The ingress DSCP is composed of ingress-dscp10 (most significant digit in the left column) and
ingress-dscp1 (least significant digit in the top row (in other words, ingress-dscp = ingress-dscp10 *
10 + ingress-dscp1); and the corresponding internal-dscp is shown at the intersecting cell in the
table.
The ingress DSCP is bitwise ANDed with the binary value 11 to determine the drop precedence. If
the resulting value is 10 binary, then the drop precedence is set to 0.
Table 120: Default Mapping of DSCP Values to Internal PHB/Drop Values