Quality of Service
QoS Advanced Mode
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4 435
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This feature changes the DSCP tags for incoming traffic switched between trusted QoS
domains. Changing the DSCP values used in one domain, sets the priority of that type of
traffic to the DSCP value used in the other domain to identify the same type of traffic.
These settings are active when the system is in the QoS Advance mode, and once activated
they are active globally.
For example: Assume that there are three levels of service: Silver, Gold, and Platinum and the
DSCP incoming values used to mark these levels are 10, 20, and 30 respectively. If this traffic
is forwarded to another service provider that has the same three levels of service, but uses
DSCP values 16, 24, and 48, Out of Profile DSCP Remarking changes the incoming values
as they are mapped to the outgoing values.
To map DSCP values:
STEP 1 Click Quality of Service > QoS Advanced Mode > Out of Profile DSCP Remarking. This
page enables setting the DSCP-value of traffic entering or leaving the device.
DSCP In displays the DSCP value of the incoming packet that needs to be re-marked to an
alternative value.
You may filter according to Action Type to display all Exceed or Violate. This enables you to
configure remarking when the traffic exceeds wither the Exceed or Violate threshold of a
policer.
STEP 2 Select the DSCP Out value to where the incoming value is mapped.
STEP 3 Click Apply. The Running Configuration file is updated with the new DSCP Remarking table.
STEP 4 Click Restore Defaults to restore the factory CoS default setting for this interface.
Class Mapping
A Class Map defines a traffic flow with ACLs (Access Control Lists) defined on it. A MAC
ACL, IP ACL, and IPv6 ACL can be combined into a class map. Class maps are configured to
match packet criteria on a match-all or match-any basis. They are matched to packets on a
first-fit basis, meaning that the action associated with the first-matched class map is the action
performed by the system. Packets that matches the same class map are considered to belong to
the same flow.
NOTE Defining class maps does not have any effect on QoS; it is an interim step, enabling the class
maps to be used later.
If more complex sets of rules are needed, several class maps can be grouped into a super-group
called a policy (see Policy Table).
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