Marking - Cisco ME 3400G-2CS - Ethernet Access Switch Software Configuration Manual

Understanding QoS
This example shows how to use the priority with police commands to configure out-class1 as the
priority queue, with traffic going to the queue limited to 20,000,000 bps so that the priority queue never
uses more than that. Traffic above that rate is dropped. This allows other traffic queues to receive some
port bandwidth, in this case a minimum bandwidth guarantee of 500,000 and 200,000 kbps. The class
class-default queue gets the remaining port bandwidth.
Switch(config)# policy-map policy1
Switch(config-pmap)# class out-class1
Switch(config-pmap-c)# priority
Switch(config-pmap-c)# police 200000000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class2
Switch(config-pmap-c)# bandwidth 500000
Switch(config-pmap-c)# exit
Switch(config-pmap)# class out-class3
Switch(config-pmap-c)# bandwidth 200000
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# service-policy output policy1
Switch(config-if)# exit

Marking

You can use packet marking in input policy maps to set or modify the attributes for traffic belonging to
a specific class. After network traffic is organized into classes, you use marking to identify certain traffic
types for unique handling. For example, you can change the CoS value in a class or set IP DSCP or IP
precedence values for a specific type of traffic. These new values are then used to determine how the
traffic should be treated. You can also use marking to assign traffic to a QoS group within the switch.
Traffic marking is typically performed on a specific traffic type at the ingress port. The marking action
can cause the CoS, DSCP, or precedence bits to be rewritten or left unchanged, depending on the
configuration. This can increase or decrease the priority of a packet through the system. The marking
function can use information from the policing function or directly from the classification function.
You can specify and mark traffic by using the set commands in a policy map for all supported QoS
markings (CoS, IP DSCP, IP precedence, and QoS groups). A set command unconditionally marks the
packets that match a specific class. You then attach the policy map to an interface as an input policy map.
Note When you configure a set qos-group command in an input policy map, you cannot configure other set
operations in the same class (such as set dscp, set cos, or set precedence).
You can also mark traffic by using the set command with table maps.Table maps list specific traffic
attributes and maps (or converts) them to another attribute. A table map establishes a to-from
relationship for the attribute and defines the change to be made.
Note When you use a table map in an input policy map, the protocol type of the from-type action in the table
map must be the same as the protocol type of the associated classification. For example, if a class map
represents an IP classification, the from-type action in the table map must be either dscp or precedence.
If the class map represents a non-IP classification, the from-type action in the table map must be cos.
After you create a table map, you configure a policy map to use the table map. See the
Management and Scheduling" section on page
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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30-18.
Chapter 30 Configuring QoS
"Congestion
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