Cisco Nexus 1000V Quality of Service Configuration Guide, Release 4.2(1)SV1(5.2)
Configuring QoS Policing
Downloads: This chapterpdf (PDF - 1.34MB) The complete bookPDF (PDF - 2.55MB) | The complete bookePub (ePub - 247.0KB) | Feedback

Configuring QoS Policing

Configuring QoS Policing

This chapter contains the following sections:

Information About Policing

Policing is the monitoring of data rates for a particular class of traffic. Cisco Nexus 1000V can also monitor associated burst sizes.

Three conditions, are determined by the policer depending on the data rate parameters supplied: conform (green), exceed (yellow), or violate (red). You can configure only one action for each condition. When the data rate exceeds the user-supplied values, packets are either marked down or dropped.

You can define single-rate or dual-rate policers. Single-rate policers monitor the specified committed information rate (CIR) of traffic. Dual-rate policers monitor both CIR and peak information rate (PIR) of traffic. For more information about policies, see RFC 2697, RFC 2698, and RFC4115.

Figure 1. Policing Condition and Types



The following conditions trigger actions by the policer depending on the defined data rate:

Table 1 Policer Actions for Exceed or Violate

Condition

Color

Description

Policer Action(only one allowed per condition)

Conform

Green

The packet traffic data rate is within the defined boundaries.

The policer either transmits these packets as is, or changes the value in the header (DSCP, precedence, or CoS), and then transmits these packets.

Exceed

Yellow

The packet traffic data rate exceeds the defined boundary.

The policer can drop or mark down these packets.

Violate

Red

The packet traffic data rate violates the defined boundaries.

The policer can drop or mark down these packets.

Prerequisites for Policing

  • You are logged on to the CLI in EXEC mode.
  • You must be familiar with RFC 2698.

Guidelines and Limitations

Each module polices independently, which might affect a policer that is applied to traffic distributed across more than one module, such as in the case of a port channel interface.

Configuring Policing

Police Command and Policer Types

Police Command Arguments

The type of policer that is created by the Cisco Nexus 1000V is based on a combination of the police command arguments.

Note


Specify the identical value for pir and cir to configure 1-rate 3-color policing.

Argument

Description

cir

Committed information rate (cir), or desired bandwidth, specified as a bit rate or a percentage of the link rate. Although a value for cir is required, the argument itself is optional. The range of values is from 1 to 80000000000; the range of policing values that are mathematically significant is 8000 to 80 Gbps.

percent

Specifies the rate as a percentage of the interface rate. The range of values is from 1 to 100%.

bc

Indication of how much the cir can be exceeded, either as a bit rate or an amount of time at cir. The default is 200 milliseconds of traffic at the configured rate. The default data rate units are bytes, and the Gigabit per second (gbps) rate is not supported for this parameter.

pir

Peak information rate (pir), which is specified as a PIR bit rate or a percentage of the link rate. There is no default. The range of values is from 1 to 80000000000; the range of policing values that are mathematically significant is from 8000 to 80 Gbps. The range of percentage values is from 1 to 100%.

be
Indication of how much the pir can be exceeded, either as a bit rate or an amount of time at pir. When the bc value is not specified, the default is 200 milliseconds of traffic at the configured rate. The default data rate units are bytes, and the Gigabit per second (gbps) rate is not supported for this parameter.
Note   

You must specify a value for pir before the device displays this argument.

conform

Single action to take if the traffic data rate is within bounds. The basic actions are transmit or one of the set commands listed in th table. The default is transmit.

exceed

Single action to take if the traffic data rate exceeds the specified boundaries. The basic actions are drop or markdown. The default is drop.

violate

Single action to take if the traffic data rate violates the configured rate values. The basic actions are drop or markdown. The default is drop.

Although all the arguments in the above table are optional, you must specify a value for cir. In this section, cir indicates what is its value but not necessarily the keyword itself. The combination of these arguments and the resulting policer types and actions are described in the following table.

Police Arguments Present

Policer Type

Policer Action

cir, but not pir, be, or violate

1-rate, 2-color

cir, then conform; otherwise violate

cir and pir

1-rate, 3-color

You must specify identical values for cir and pir.

cir and pir

2-rate, 3-color

cir, then conform; ≤ pir, then exceed; otherwise violate

Policer Action

You can take the following actions when the packet exceeds the parameters or violates the parameters:

Action

Description

drop

Drops the packet. This action is available only when the packet exceeds or violates the parameters.

set dscp dscp table {cir-markdown-map | pir-markdown-map}

Sets the specified fields from a table map and transmits the packet. For more information on the system-defined, or default table maps, see Configuring QoS Marking Policies. This is available only when the packet exceeds the parameters (use the cir-markdown-map) or violates the parameters (use the pir-markdown-map).

Action

Description

transmit

Transmits the packet. This action is available only when the packet conforms to the parameters.

set-prec-transmit

Sets the IP precedence field to a specified value and transmits the packet. This action is available only when the packet conforms to the parameters.

set-dscp-transmit

Sets the DSCP field to a specified value and transmits the packet. This action is available only when the packet conforms to the parameters.

set-cos-transmit

Sets the CoS field to a specified value and transmits the packet. This action is available only when the packet conforms to the parameters.

set-qos-transmit

Sets the QoS group internal label to specified value and transmits the packet. This action can be used only in input policies and is available only when the packet conforms to the parameters.

set-discard-class-transmit

Sets the discard-class internal label to a specified value and transmits the packet. This action can be used only in ingress policies and is available only when the packet conforms to the parameters.

Police Command Data Rates

The policer can only drop or mark down packets that exceed or violate the specified parameters. For information see, Configuring QoS Marking Policies on marking down packets.

The police command uses the following data rates:

Table 2 Data Rates for the police Command

Rate

Description

bps

Bits per second (default)

kbps

1,000 bits per seconds

mbps

1,000,000 bits per second

gbps

1,000,000,000 bits per second

Police Command Burst Sizes

The police command uses the following Burst sizes:

Speed

Description

bytes

bytes

kbytes

1,000 bytes

mbytes

1,000,000 bytes

ms

milliseconds

us

microseconds

Configuring 1-Rate and 2-Rate, 2-Color and 3-Color Policing


Note


You must specify the identical value for pir and cir to configure 1-rate, 3-color policing.
Procedure
     Command or ActionPurpose
    Step 1switch# configure terminal 

    Enters global configuration mode.

     
    Step 2switch(config)# policy-map [type qos] [match-first] policy-map-name 

    Places you into policy map QoS configuration mode for the specified policy map and configures the map name in the running configuration.

    The policy_map_name argument is an alphabetic string that can be up to 40 case-insensitive characters long, including hyphen (-) and underscore (_) characters.

     
    Step 3switch(config-pmap-qos)# class [type qos] {class_map_name |class-default} 

    Creates a reference to class-map-name and enters policy-map class QoS configuration mode for the specified class map. By default, the class is added to the end of the policy map. Changes are saved in the running configuration.

    Use the class-default keyword to select all traffic that is not currently matched by classes in the policy map.

     
    Step 4switch(config-pamp-c-qos)# police[cir] {committed-rate [data-rate] | percent cir-link-percent} [bc committed-burst-rate [link-speed]][pir] {peak-rate [data-rate] | percent cir-link-percent} [be peak-burst-rate [link-speed]] [conform {transmit | set-prec-transmit | set-dscp-transmit | set-cos-transmit | set-qos-transmit | set-discard-class-transmit} [exceed {drop | set dscp dscp table {cir-markdown-map}} [violate {drop | set dscp dscp table {pir-markdown-map}}]} 

    Polices cir in bits or as a percentage of the link rate. The conform action is taken if the data rate is ≤cir. If be and pir are not specified, all other traffic takes the violate action. If be or violate are specified, the exceed action is taken if the data rate ≤ pir; otherwise. The actions are described in Information About Policing. The data rates and link speeds are described in Police Command Data Rates and Police Command Burst Sizes.

     
    Step 5switch(config-pamp-c-qos)# show policy-map [type qos] [policy-map-name]  (Optional)

    Displays information about all configured policy maps or a selected policy map of type QoS.

     
    Step 6switch(config-pmap-c-qos)# copy running-config startup-config   (Optional)

    Saves the running configuration persistently through reboots and restarts by copying it to the startup configuration.

     

    This example shows how to configure a 1-rate, 2-color policer that transmits if the data rate is within 200 milliseconds of traffic at 256000 bps and marks IP precedence to 6 if the data rate is exceeded.

    switch# configure terminal
    switch(config)# policy-map policy1
    switch(config-pmap-qos)# class class-default
    switch(config-pmap-c-qos)# police cir 256000 conform transmit violate set dscp dscp table pir-markdown-map
    switch(config-pmap-c-qos)# 
    
    

    This example shows how to configure a 1-rate, 3-color policer that transmits if the data rate is within 200 milliseconds of traffic at 256000 bps, and marks DSCP to 6 if the data rate is within 300 milliseconds of traffic at 256000bps, and drops packets otherwise.


    Note


    You must specify identical values for cir and pir for a 1R3C policer.


    switch# configure terminal
    switch(config)# policy-map policy1
    switch(config-pmap-qos)# class class-default
    switch(config-pmap-c-qos)# police cir 256000 pir 256000 conform transmit exceed set dscp dscp table cir-markdown-map violate drop
    switch(config-pmap-c-qos)# 
    
    

    Configuring Ingress and Egress Policing

    You can apply the policing instructions in a QoS policy map to ingress or egress packets by attaching that QoS policy map to an interface or port profile. To select ingress or egress, you specify either the input or output keyword in the service-policy command. For an example of how to use the service-policy command, see Creating Ingress and Egress Policies.

    Configuring Markdown Policing

    Markdown policing is the setting of a QoS field in a packet when traffic exceeds or violates the policed data rates. You can configure markdown policing by using the set commands for conform described in Configuring 1-Rate and 2-Rate, 2-Color and 3-Color Policing.

    Procedure
       Command or ActionPurpose
      Step 1switch# configure terminal 

      Enters global configuration mode.

       
      Step 2switch(config)# policy-map [type qos] [match-first] policy-map-name 

      Places you into policy map QoS configuration mode for the specified policy map and configures the map name in the running configuration.

      The policy_map_name argument is an alphabetic string that can be up to 40 case-insensitive characters long, including hyphen (-) and underscore (_) characters.

       
      Step 3switch(config-pmap-qos)# class [type qos] {class_map_name |class-default} 

      Creates a reference to class-map-name and enters policy-map class QoS configuration mode for the specified class map. By default, the class is added to the end of the policy map. Changes are saved in the running configuration.

      Use the class-default keyword to select all traffic that is not currently matched by classes in the policy map.

       
      Step 4switch(config-pamp-c-qos)# police[cir] {committed-rate [data-rate] | percent cir-link-percent} [bc committed-burst-rate [link-speed]][pir] {peak-rate [data-rate] | percent cir-link-percent} [be peak-burst-rate [link-speed]] [conform action [exceed {drop | set dscp dscp table cir-markdown-map} [violate {drop | set dscp dscp table pir-markdown-map}]]}} 

      Polices cir in bits or as a percentage of the link rate. The conform action is taken if the data rate is ≤ cir. If be and pir are not specified, all other traffic takes the violate action. If be or violate are specified, then the exceed action is taken if the data rate ≤ pir, and the violate action is taken otherwise.

       
      Step 5switch(config-pamp-c-qos)# show policy-map [type qos] [policy-map-name]  (Optional)

      Displays information about all configured policy maps or a selected policy map of type QoS.

       
      Step 6switch(config-pmap-c-qos)# copy running-config startup-config   (Optional)

      Saves the running configuration persistently through reboots and restarts by copying it to the startup configuration.

       

      This example shows a 1-rate, 3-color policer that transmits if the data rate is within 300 milliseconds of traffic at 256000 bps; marks down DSCP using the system-defined table map if the data rate is within 300 milliseconds of traffic at 256000 bps; and drops packets otherwise:

      switch# config termnal
      switch(config)# policy-map policy1
      switch(config-pmap-qos)# class class-default
      switch(config-pmap-c-qos)# police cir 256000 bps bc 300 ms pir 256000 conform transmit exceed set dscp dscp table cir-markdown-map violate drop
      switch(config-pmap-c-qos)# show policy-map policy1 
      
      Type qos policy-maps
        ====================
      
        policy-map type qos policy1
          class  class-default
            police cir 256000 bps bc 300 ms pir 256000 bps be 300 ms conform transmit
      exceed set dscp dscp table cir-markdown-map violate drop
      
      switch(config-pmap-c-qos)# copy running-config startup-config

      Verifying the Policing Configuration

      Use the following command to verify the configuration:

      Command

      Description

      show policy-map

      Displays information about policy maps and policing.

      Configuration Example for QoS Policing

      The following example shows how to configure a 1-rate, 2-color policer:

      switch# configure terminal
      switch(config)# policy-map policy1
      switch(config-pmap-qos)# class one_rate_2_color_policer
      switch(config-pmap-c-qos)# police cir 256000 conform transmit violate drop

      The following example shows how to configure a 1-rate, 2-color policer with DSCP mark down:

      switch# configure terminal
      switch(config)# policy-map policy2
      switch(config-pmap-qos)# class one_rate_2_color_policer_with_dscp_markdown
      switch(config-pmap-c-qos)# police cir 256000 conform set-dscp-transmit af11 violate set dscp dscp table pir-markdown-map

      The following example shows how to configure a 1-rate, 3-color policer:

      switch# configure terminal
      switch(config)# policy-map policy3
      switch(config-pmap-qos)# class one_rate_3_color_policer
      switch(config-pmap-c-qos)# police cir 256000 pir 256000 conform transmit exceed set dscp dscp table cir-markdown-map violate drop

      Feature History for QoS Policing

      This section provides the QoS policing release history.

      Feature Name

      Release

      Feature Information

      QoS Policing

      4.0

      This feature was introduced