ECS4660-28F_Management Guide-R03

C HAPTER 41 | Class of Service Commands
Priority Commands (Layer 3 and 4)
– 1397 –
DEFAULT SETTING.
COMMAND MODE
Interface Configuration (Port)
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 178, 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)#
Table 178: 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.