Reference Guide

580 | Quality of Service
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Set DSCP values for egress packets based on flow
Match-any Layer 3 flows may have several match criteria. All flows that match at least one of the match
criteria are mapped to the same queue since they are in the same class map. Setting a DSCP value from
QOS-POLICY-IN mode (see Set a DSCP value for egress packets) assigns the same DSCP value to all of
the matching flows in the class-map. The Flow-based DSCP Marking feature allows you to assign different
DSCP to each match criteria CLASS-MAP mode using the option
set-ip-dscp with the match command so
that matching flows within a class map can have different DSCP values, as shown in Figure 30-11. The
values you set from CLASS-MAP mode override the value you QoS input policy DSCP value, and packets
matching the rule are marked with the specified value.
Figure 30-11. Marking Flows in the Same Queue with Different DSCP Values
Display configured class maps and match criteria
Display all class-maps or a specific class map using the command show qos class-map from EXEC
Privilege mode.
FTOS#show run class-map
!
class-map match-any example-flowbased-dscp
match ip access-group test set-ip-dscp 2
match ip access-group test1 set-ip-dscp 4
match ip precedence 7 set-ip-dscp 1
FTOS#show run qos-policy-input
!
qos-policy-input flowbased
set ip-dscp 3
FTOS# show cam layer3 linecard 2 port-set 0
Cam Port Dscp Proto Tcp Src Dst SrcIp DstIp DSCP Queue
Index Flag Port Port Marking
-------------------------------------------------------------------------------------------
-----
16260 1 0 TCP 0x0 0 0 1.1.1.0/24 0.0.0.0/0 2 0
16261 1 0 UDP 0x0 0 0 2.2.2.2/32 0.0.0.0/0 4 0
16262 1 56 0 0x0 0 0 0.0.0.0/0 0.0.0.0/0 1 0
24451 1 0 0 0x0 0 0 0.0.0.0/0 0.0.0.0/0 - 0