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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 41 Configuring PFC QoS
Common QoS Scenarios
The difference between this policer configuration and the marking configuration is the policy-map action
statements. The marking example uses the
set dscp
command to mark the traffic with a particular DSCP
value. This policing example marks the CLASSIFY-OTHER traffic to a DSCP value of zero and polices
that traffic to 50 Mbps. To do this, replace the
set dscp
command with a
police
command. The
police
command allows a marking action to take place: it marks all traffic below the 50 Mbps limit to DSCP 0
and drops any traffic above the 50 Mbps threshold.
This is the modified IPPHONE-PC policy map, which includes the
police
command:
policy-map IPPHONE-PC
class CLASSIFY-OTHER
police 50000000 1562500 conform-action set-dscp-transmit default exceed-action drop
These are the
police
command parameters:
•
The 50000000 parameter defines the committed information rate (CIR) for traffic allowed in this
traffic class. This example configures the CIR to be 50 Mbps.
•
The 1562500 parameter defines the CIR burst size for traffic in this traffic class; this example uses
a default maximum burst size. Set the CIR burst size to the maximum TCP window size used on the
network.
•
The
conform action
keywords define what the policer does with CLASSIFY-OTHER packets
transmitted when the traffic level is below the 50Mbps rate. In this example,
set-dscp-transmit
default
applies DSCP 0 to those packets.
•
The
exceed action
defines what the policer does with CLASSIFY-OTHER packets transmitted when
the traffic level is above the 50 Mbps CIR. In this example,
exceed action drop
drops those packets.
This is a basic example of a single rate per-interface aggregate policer. The Supervisor Engine 2 and
Supervisor Engine 720 forwarding engines also support a dual-rate policer for providing both CIR and
peak information rate (PIR) granularity.
Attach the policy map to the appropriate interface using the
service-policy input
command:
interface FastEthernet5/1
service-policy input IPPHONE-PC
To monitor the policing operation, use these commands:
show policy-map interface fastethernet 5/1
show class-map
show mls qos ip fastethernet 5/1
