Cisco CRS Command Reference Manual page 71

Quality of Service Commands on the Cisco IOS XR Software
For police rate commands, interpret the percent keyword in this way:
• For a one-level policy, the percent keyword specifies the CIR as a percentage of the link rate. For
• For a two-level policy, in the parent policy, the percent keyword specifies the parent CIR as a percentage
Note Configured values take into account the Layer 2 encapsulation applied to traffic. This applies to both
ingress and egress policing. For POS/SDH transmission, the encapsulation is considered to be 4 bytes.
For Ethernet, the encapsulation is 14 bytes; whereas for 802.1Q, the encapsulation is 18 bytes.
The policer uses an incremental step size of 256 kbps. The configured value is rounded down to the nearest
256 kbps. The value shown in the output of the running-configuration shows the configured value as entered
by the user.
If the burst value is not specifically configured, it is automatically set to equate to 250 msec-worth of the CIR
value. For example, if a CIR value of 1000000 kbps is entered, the burst value is calculated to be
32000000 bytes. However, the maximum burst value supported is 2,097,120 bytes.
Hierarchical policing is also supported. In such a configuration, both parent and child policies have class-maps
containing policing statements, as in this example:
!
policy-map child
class gold
police rate percent 50
conform-action set precedence immediate
exceed-action drop
!
!
policy-map parent
class match_all
police rate 10000 kbps burst 15000
exceed-action drop
service-policy child
!
Task ID
Task ID
qos
Examples
In this example for MPLS, traffic policing is configured with the average rate at 250 kbps, and the normal
burst size at 50 bytes for all packets leaving GigabitEthernet interface 0/1/0/9:
RP/0/RP0/CPU0:router(config)# class-map class1
RP/0/RP0/CPU0:router(config-cmap)# match mpls experimental topmost 0
RP/0/RP0/CPU0:router(config-cmap)# exit
RP/0/RP0/CPU0:router(config)# policy-map policy1
RP/0/RP0/CPU0:router(config-pmap)# class class1
RP/0/RP0/CPU0:router(config-pmap-c)# police rate 250 kbps burst 50
OL-23235-03
example, the command police rate percent 35 configures the CIR as 35% of the link rate.
of the link rate. In the child policy, the percent keyword specifies the child CIR as a percentage of the
maximum policing or shaping rate of the parent. If traffic policing or shaping is not configured on the
parent, the parent inherits the interface policing or shaping rate.
Cisco IOS XR Modular Quality of Service Command Reference for the Cisco CRS Router, Release 4.0
Operations
read, write
police rate
65