Class of Service
122
Instruction Manual - NXA-ENET8-POE+
Perform these steps to configure the trust mode:
1.
Click
Traffic
>
Priority
>
Trust Mode
.
2.
Set the trust mode for any port.
3.
Click
Apply
.
Mapping Ingress DSCP Values to Internal DSCP Values
Use the Traffic > Priority > DSCP to DSCP page to map DSCP values in incoming packets to per-hop behavior and drop precedence
values for internal priority processing.
The DSCP is six bits wide, allowing coding for up to 64 different forwarding behaviors. The DSCP replaces the ToS bits, but it retains
backward compatibility with the three precedence bits so that non-DSCP compliant, ToS-enabled devices, will not conflict with the
DSCP mapping. Based on network policies, different kinds of traffic can be marked for different kinds of forwarding.
Command Usage
Enter per-hop behavior and drop precedence for any of the DSCP values 0 - 63.
This map is only used when the priority mapping mode is set to DSCP (see page 121), 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.
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 following table lists the options on this page:
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.
FIG. 135
Setting the Trust Mode
Traffic - Priority (DSCP to DSCP) Options
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 for controlling traffic congestion. (Range: 0 - Green, 3 - Yellow, 1 - Red)
Default Mapping of DSCP Values to Internal PHB/Drop Values
ingress-dscp1
in
gr
es
s-d
sc
p1
0
0
1
2
3
4
5
6
7
8
9
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