Chapter 9
| Class of Service
Layer 3/4 Priority Settings
– 222 –
â—† This map is only used when the priority mapping mode is set to DSCP (see
page 220), and the ingress packet type is IPv4. Any attempt to configure the
DSCP mutation map will not be accepted by the switch, unless the trust mode
has been set to DSCP.
â—† 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.
Parameters
These parameters are displayed:
◆ Port – Specifies a port.
◆ DSCP – DSCP value in ingress packets. (Range: 0-63)
◆ 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)
Table 16: 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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