Mapping DSCP Priority
The DSCP is six bits wide, allowing coding for up to 64 different forwarding
behaviors. The DSCP replaces the ToS bits, and it retains backward compatibili-
ty with the three precedence bits so that non-DSCP compliant, ToS-enabled
devices, will not conflict with the DSCP mapping. Based on network policies, dif-
ferent kinds of traffic can be marked for different kinds of forwarding. The DSCP
default values are defined in the following table. Note that all the DSCP values
that are not specified are mapped to CoS value 0.
IP DSCP Value
CoS Value
0
0
8
1
10, 12, 14, 16
2
18, 20, 22, 24
3
26, 28, 30, 32, 34, 36
4
38, 40, 42
5
48
6
46, 56
7
Command Attributes
> IP Precedence/DSCP Priority Status – Selects IP Precedence, DSCP, or dis-
ables both priority services.
> DSCP Priority Table – Shows the DSCP Priority to CoS map.
> Class of Service Value – Maps a CoS value to the selected DSCP Priority
value. Note that “0” represents low priority and “7” represent high priority.
Web – Click Priority/IP DSCP Priority. Select “IP DSCP” from the IP
Precedence/DSCP Priority Status menu. Select a DSCP priority value from the
DSCP Priority Table by clicking on it with your cursor, enter a value in the Class
of Service Value field, and then click “Apply.”
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