Chapter 20
| Class of Service Commands
Priority Commands (Layer 3 and 4)
– 512 –
qos map
dscp-mutation
This command maps DSCP 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 dscp-mutation phb drop-precedence from dscp0 ... dscp7
no qos map dscp-mutation dscp0 ... dscp7
phb - Per-hop behavior, or the priority used for this router hop. (Range: 0-7)
drop-precedence - Drop precedence used in controlling traffic congestion.
(Range: 0 - Green, 3 - Yellow, 1 - Red)
dscp - DSCP value in ingress packets. (Range: 0-63)
DEFAULT SETTING.
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
Table 109: Default Mapping of DSCP Values to Internal PHB/Drop Values
ingress-
dscp1
ingress-
dscp10
0123456789
0 0,0 0,1 0,0 0,3 0,0 0,1 0,0 0,3 1,0 1,1
1 1,0 1,3 1,0 1,1 1,0 1,3 2,0 2,1 2,0 2,3
2 2,0 2,1 2,0 2,3 3,0 3,1 3,0 3,3 3.0 3,1
3 3,0 3,3 4,0 4,1 4,0 4,3 4,0 4,1 4.0 4,3
4 5,0 5,1 5,0 5,3 5,0 5,1 6,0 5,3 6,0 6,1
5 6,0 6,3 6,0 6,1 6,0 6,3 7,0 7,1 7.0 7,3
6 7,0 7,1 7,0 7,3
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.
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