Policer Adjustment in QoS Policy Map

Policers are configured usually at a value range of 64,000–10 G whereas the hardware policer is programmed only to discrete value. The policer rate received is less than that of the configured CIR and PIR values. The policer adjustment feature is added to adjust the CIR and PIR values of hardware policer either to match the configured value or to the next higher value available in hardware.

The policer adjustment feature is supported on the RSP3 module.

To enable policer adjustment, use the platform qos-adjust-policer enable at the global configuration mode for a table map. You can view the show platform hardware pp active feature QoS interface command to compare the configured values of CIR and PIR values in the qos-policy and the actual programmed values in hardware.

With the policer adjustment feature, the policer rate is compensated with + 0 to + 0.5 to the configured policer rate so that you can achieve the received rate more than or equal to that of the configured rate.

Restrictions for Policer Adjustment

  • Policy adjustment is performed at a global configuration level and it is not supported on each port or EFP.

  • Detaching and attaching of policer from ports after applying the policy adjustment feature at a global configuration works for applied ports. For the remaining ports to which detaching and attaching is not performed after enabling the policy adjustment works in a legacy QoS functionality manner.

  • Policer enhancement is supported on EFP, TEFP, routed port, and port channel.

  • BC or BE values are not adjusted, and only CIR and PIR or EIR are adjusted. Even if BC or BE values are configured, the values that are displayed in the show command do not match exactly with IOS values.

  • CIR rates 64,000–3,00,000 can have rates more than 0.5 percent as this rate limits to already available percent and effects higher rates.

How to configure Policer Adjustment

Enabling Policer Adjustment

To enable a policer adjustment at the global configuration mode, enter the following command:


Router> enable
Router# configure terminal
Router(config)# platform qos-adjust-policer enable

Note

After enabling the policer adjustment, you must detach and attach the policer from port, then only the feature is applied on the port.

To disable the policer adjustment globally, enter the no form of the following command:


{no} platform qos-adjust-policer enable

Note

After disabling the policer adjustment, you need to detach and attach the existing policy-map from the port or service. Only then will the policer adjustment be disabled.

Disabling Policer Adjustment

To disable the policer adjustment globally, enter the no form of the following command:


{no} platform qos-adjust-policer enable

After disabling the policer adjustment, you need to detach and attach the existing policy-map from the port or service and then only the policer adjustment is disabled.

Viewing QoS Policer Values for Ingress Traffic

To view the software and ASIC QoS policer values for egress traffic, use the following command: 
show platform hardware pp active feature QoS interface  {interface-type interface-number} service-instance  {service-instance-id} input 

Router# show platform hardware pp active feature qos interface te 0/0/13 ser 2 in

Policy details:
 
Interface: TenGigabitEthernet0/0/13
Policy: TMO-EVC
Service instance number: 2
Direction: input
-------------------------------------------------------------------
Class: EVC, Level: 2
Policer Mode: IETF_2R3C
Policer Index Id: 33
Policer Profile Id: 12
Policer feature         Software value             Asic value
CIR                        5000000 kbps             5062500 kbps
PIR                        7000000 kbps                  NA
EIR (PIR - CIR)            2000000 kbps             2024884 kbps
BC                         2500000 bytes            2500000 bytes
BE                        16000000 bytes           16000000 bytes

Monitoring QoS Policer Values

The QoS policer values provide crucial insights about the network performance.

  • The configured QoS policer values are also referred to as software values.

  • The hardware-programmed QoS policer values are also referred to as ASIC values.

The software values might differ from the ASIC values due to hardware limitations. The ASIC may round the software values to the nearest or next higher supported value, ensuring compatibility and efficient application of QoS policies.

Understanding the differences between software and ASIC QoS policer values is essential for network optimization. Regular review and fine-tuning of these settings ensure that applications receive the necessary bandwidth, priority, and resources. Recognizing these differences is also crucial for troubleshooting. Comparing the values can help identify the root cause and resolve performance problems more effectively.

Configuring the display of ASIC QoS Policer Values for Egress Traffic

Table 1. Feature History

Feature Name

Release Information

Description

Displaying ASIC QoS Policer Values for Egress Traffic

 Cisco IOS XE 17.15.1b

In addition to Ingress traffic, you can now view the programmed hardware (ASIC) values of the QoS features configured for Egress traffic.

Use the following command to enable ASIC values:
platform qos-egress-hw-param enable

The programmed hardware (ASIC) value may differ from the configured software value due to hardware limitations. Now, you can compare the actual QoS policer value programmed in the hardware with the value you configured in the software for egress traffic.

Viewing the ASIC values for egress traffic is a two-step process.

  1. Enabling the display of ASIC values for egress traffic

  2. Viewing ASIC values for egress traffic

Enabling the display of ASIC Values for Egress Traffic

The following example shows how to enable the display of ASIC values:


                Router> enable
                Router# configure terminal
                Router(config)# platform qos-egress-hw-param enable

To disable the display of ASIC values for egress traffic, enter the no form of the following command:


                {no} platform qos-egress-hw-paramenable

Viewing ASIC Values for Egress Traffic

To view the software and ASIC QoS policer values for egress traffic, use the following command: 
show platform hardware pp active feature QoS interface  {interface-type interface-number} service-instance  {service-instance-id} output 

                Router# show platform hardware pp active feature qos interface GigabitEthernet0/1/0  service-instance 10 output
                Policy details:
                 
                Interface: GigabitEthernet0/1/0
                Policy: EGRESS
                Service instance number: 10
                
                Direction: outpu
                -------------------------------------------------------------------
                Class:                          Parent_EGR 	    Level: 1
                Egress QueueId:                   NA
                Queueing Feature           Software Value            Asic Value
                Priority level:                  NA                      NA
                Shape PIR (in kbps):           1000000              1000000
                Shape PIR burst (in bits):     18432                  18432
                Bandwidth:                       NA                      NA
                Inverse Bandwidth Ratio:         NA                      NA
                Queue-limit:                     NA                      NA
                -------------------------------------------------------------------
                Class:                          Parent_EGR            Level: 2
                Egress QueueId:                  NA
                Queueing Feature           Software Value            Asic Value
                Priority level:                 NA                      NA
                Shape PIR (in kbps):          700000                  700000
                Shape PIR burst (in bits):    7000000                 7000000
                Bandwidth:                      NA                      NA
                Inverse Bandwidth Ratio:        NA                      NA
                Queue-limit:                    NA                      NA
                -------------------------------------------------------------------
                Class:                          qos_group1             Level: 3
                Egress QueueId:                  8729
                Queueing Feature           Software Value            Asic Value
                Priority level:                  1                       1
                Shape PIR (in kbps):          140000                  140000
                Shape PIR burst (in bits):    28000112                28000112
                Bandwidth:                    140000                  140000
                Inverse Bandwidth Ratio:        NA                      NA
                Queue-limit:                  525000                   525312
                -------------------------------------------------------------------
                Class:                          qos_group2              Level: 3
                Egress QueueId:                 8730
                Queueing Feature           Software Value            Asic Value
                Priority level:               2                            2
                Shape PIR (in kbps):          210000                    210000
                Shape PIR burst (in bits):    40000112                  40000112
                Bandwidth:                    200000                    200000
                Inverse Bandwidth Ratio:        NA                        NA
                Queue-limit:                  200000                    200000
                -------------------------------------------------------------------
                Class:                          qos_group3              Level: 3
                Egress QueueId:                 8731
                Queueing Feature           Software Value            Asic Value
                Priority level:                  NA                      NA
                Shape PIR (in kbps):          700000                    700000
                Shape PIR burst (in bits):    7000000                   7000000
                Bandwidth:                    140000                    140000
                Inverse Bandwidth Ratio:      20                        20
                Queue-limit:                  1024000                   1024000
                -------------------------------------------------------------------
                Class:                          qos_group4              Level: 3
                Egress QueueId:                 8732
                Queueing Feature           Software Value            Asic Value
                Priority level:                  NA                      NA
                Shape PIR (in kbps):          700000                  700000
                Shape PIR burst (in bits):    7000000                7000000
                Bandwidth:                    70000                    70000
                Inverse Bandwidth Ratio:      10                        10
                Queue-limit:                  1024000                1024000
                -------------------------------------------------------------------
                Class:                          class-default           Level: 3
                Egress QueueId:                 8728
                Queueing Feature           Software Value            Asic Value
                Priority level:                  NA                      NA
                Shape PIR (in kbps):          1000000                 1000000
                Shape PIR burst (in bits):    18432                   18432
                Bandwidth:                      0                       0
                Inverse Bandwidth Ratio:        1                       1
                Queue-limit:                  1677721                1678336
                WRED parameters for Green Color:
                Minimum Threshold: 1500000 bytes,       Maximum Threshold: 1677721 bytes
                Mark probability:  10
                WRED parameters for Yellow Color:
                Minimum Threshold: 0 bytes,     Maximum Threshold: 0 bytes
                Mark probability:  10
                ###################################################################
                LIF Profile Number: 0
                IVE Profile Number: 0
                EVE Profile Number: 0