Configuring Ingress Policing

This chapter contains the following sections:

Information About Ingress Policing

Policing allows you to monitor the data rates for a particular class of traffic. When the data rate exceeds user-configured values, the switch drops packets immediately. Because policing does not buffer the traffic; transmission delays are not affected. When traffic exceeds the data rate on a specific class, the switch drops the packets.

You can define single-rate and two-color Ingress Policing.

Single-rate Ingress Policing monitors the committed information rate (CIR) of traffic.


Note

The committed information rate (CIR) is a value specified as a bit rate from 1 to 80000000000 or a percentage of the link rate.

In addition, Ingress Policing can monitor associated burst sizes of the packets. Two colors, or conditions, are determined by Ingress Policing for each packet depending on the data rate parameters that you supply.

You can configure only one action for each condition. For example, you might police for traffic in a class to conform to the data rate of 256000 bits per second with up to 200 millisecond bursts.

Color-aware Ingress Policing assumes that traffic has been previously marked with a color.

Table 1 Maximum Supported Hardware Configuration for Policers
  Nexus 5500 Series Nexus 2232 Nexus 2248TP-E Nexus 6000 Series

Burst Size

64 MB

32 MB

32 MB

64 MB

Max Rate

96 Gbps

12 Gbps

8 Gbps

8 Gbps

Granularity

732 kbps

732 kbps

488 kbps

122 kbps

Guidelines and Limitations for Ingress Policing

  • The configuration for Ingress Policing is a part of the Quality of Service (QoS) policy configuration. You can configure QoS policies with Ingress Policing on the following :

    • Layer 2 switch ports

    • Host interface (HIF) ports

    • Port channels with switch ports

    • Port channels with HIF ports

    • Layer 3 interfaces (but not sub-interfaces or Switched Virtual Interfaces (SVIs))

    • Virtual Port Channel (vPC)

  • Statistics are provided with Ingress Policing. Statistics include the drop count and allowed count. You can display the statistics by entering the show policy-map interface ethernet command.

  • QoS policies that you configure on the attachments are installed in the QoS region of the Ternary Content Addressable Memory (TCAM) and causes the switch to apply Ingress Policing.

  • If you configure a QoS policy with Ingress Policing on a HIF port or port channel, Ingress Policing is offloaded to the Fabric Extender (FEX). Policy rewrites occur only in the switch.

  • All the match/set criteria that are supported in a QoS policy are supported even with Ingress Policing present in the policy. A Fabric Extender (FEX) supports Layer 3 operations (fragments) and Layer 4 operations (source and destination port ranges) but not the Transmission Control Protocol (TCP) flags and Layer 2 operations.

  • You can define match criteria for a QoS policy so that it matches the control protocol traffic. If the type of policy is configured with Ingress Policing on an HIF port, the control traffic also gets policed. Therefore, the match criteria must be specific to the required flow of traffic.

  • The switch cannot apply a QoS policy with Ingress Policing to an HIF port that has virtual Ethernet interfaces attached.

  • If the switch applies Ingress Policing on the HIF port, the policer is applied to traffic with no Virtual Network Tag (VNTAG).

  • A policy with Ingress Policing is allowed only on switch ports, HIF ports, and port channels with switch/HIF ports.

  • Ingress Policing with Layer 2 operations and TCP flags in the match criteria is not allowed on FEX interfaces.

  • Ingress Policing is not supported on Enhanced VPC (2LayerVPC) ports.

  • It is recommended that you apply identical Ingress Policing on Dual-homed (AA) HIF interfaces.

  • The police command is not supported on system QoS policies.

  • The show policy-map interface command is recommended to check that the ingress rate limiter is conformed and to display violated statistics. The CLI displays conformed/violated packets and packet per second statistics on HIF interfaces (regular as well as port-channel), whereas on the switchport (regular as well as port-channel) the command displays conformed/violated bytes and bits per second (bps).

Creating a Policy Map Using a Committed Information Rate

Procedure
     Command or ActionPurpose
    Step 1switch# configure terminal  

    Enters global configuration mode.

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

    Creates a named object that represents a set of policies that are applied to a set of traffic classes. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

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

    Associates a class map with the policy map and enters configuration mode for the specified system class. Use the class-default keyword to select all traffic that is currently not matched by classes in the policy map.

    The class-map-name argument can be a maximum of 40 characters. The name is case sensitive and can only contain alphanumeric characters, hyphens, and underscores.

     
    Step 4switch(config-pmap-c-qos)# police [cir] {committed-rate [data-rate] | percent cir-link-percent} [ [bc] {committed-burst-rate}][conform{transmit} [violate {drop}]]]  

    Polices cir in bits, kbps, mbps, or gbps. The conform action is applied if the data rate is less than or equal to cir, otherwise, the violate action is applied.

    The cir keyword specifies to use the committed information rate, or desired bandwidth, as a bit rate or a percentage of the link rate.

    The committed-rate value can range from 1 to 80 Gbps.

    The data-rate value can be one of the following:

    • bps—bits per second

    • kbps—1000 bits per second

    • mbps—1,000,000 bits per second

    • Gbps—1,000,000,000 bits per second

    Values for committed-burst-rate are the following:

    • bytes—bytes

    • kbytes—1000 bytes

    • mbytes—1,000,000 bytes

    • ms—milliseconds

    • us—microseconds

    The following are the Ingress Policing actions:

    • conform—The action to take if the traffic data rate is within bounds. The default action is transmit.

    • transmit—Transmits the packet. This is available only when the packet conforms to the parameters.

    • violate—The action to take if the traffic data rate violates the configured rate values. The basic and default action is drop.

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

     
    Step 5switch(config-pmap-c-qos)# exit  

    Exits policy-map class configuration mode and enters policy-map mode.

     
    Step 6switch(config-pmap-qos)# exit  

    Exits policy-map mode and enters configuration mode.

     
    Step 7switch(config)# show policy-map [type qos] [policy-map-name]   (Optional)

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

     

    This example shows how to create a policy map with Ingress Policing using the committed information rate: 

    switch# configure terminal
switch(config)# policy-map type qos pm1
switch(config-pmap-qos)# class type qos cm1
switch(config-pmap-c-qos)# police cir 10 mbps bc 20 kbytes
switch(config-pmap-c-qos)# set qos-group 4
switch(config-pmap-c-qos)# end
switch# show policy-map type qos pm1

 Type qos policy-maps
  ====================

  policy-map type qos pm1 
  class type qos cm1
  set qos-group 4
  police cir 20 mbytes conform transmit violate drop 
  set qos-group 4
  class type qos class-default
  set qos-group 1
  switch#

    Creating a Policy Map Using a Percentage of the Interface Rate

    Procedure
       Command or ActionPurpose
      Step 1switch# configure terminal  

      Enters global configuration mode.

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

      Creates a named object that represents a set of policies that are applied to a set of traffic classes. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

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

      Associates a class map with the policy map and enters configuration mode for the specified system class. Use the class-default keyword to select all traffic that is currently not matched by classes in the policy map.

      The class-map-name argument can be a maximum of 40 characters. The name is case sensitive and can only contain alphanumeric characters, hyphens, and underscores.

       
      Step 4switch(config-pmap-c-qos)# police [cir] {committed-rate [data-rate] | percent cir-link-percent} [ [bc] {committed-burst-rate}][conform{transmit} [violate {drop}]]]  

      Polices cir in bits, kbps, mbps, or gbps. The conform action is applied if the data rate is less than or equal to cir, otherwise, the violate action is applied.

      The cir keyword specifies to use the committed information rate, or desired bandwidth, as a bit rate or a percentage of the link rate.

      The cir-link-percent value can range from 1 to 100 percent.

      Values for committed-burst-rate are the following:

      • bytes—bytes

      • kbytes—1000 bytes

      • mbytes—1,000,000 bytes

      The following are the Ingress Policing actions:

      • conform—The action to take if the traffic data rate is within bounds. The default action is transmit.

      • transmit—Transmits the packet. This is available only when the packet conforms to the parameters.

      • violate—The action to take if the traffic data rate violates the configured rate values. The basic and default action is drop.

      • drop—Drops the packet. This is available only when the packet exceeds or violates the parameters.

       
      Step 5switch(config-pmap-c-qos)# exit  

      Exits policy-map class configuration mode and enters policy-map mode.

       
      Step 6switch(config-pmap-qos)# exit  

      Exits policy-map mode and enters configuration mode.

       
      Step 7switch(config)# show policy-map [type qos] [policy-map-name | qos-dynamic]   (Optional)

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

       

      This example shows how to create a policy map with Ingress Policing using the percentage of the interface rate: 

      switch# configure terminal
switch(config)# policy-map type qos pm-test1
switch(config-pmap-qos)# class type qos cm-cos4
switch(config-pmap-c-qos)# police cir percent 10 bc 40 kbytes conform transmit violate drop
switch(config-pmap-c-qos)# end
switch# show policy-map type qos pm-test1

Type qos policy-maps
====================

policy-map type qos pm-test1 
class type qos cm-cos4
set qos-group 4
police cir percent 10 bc 40 kbytes conform transmit violate drop 
class type qos class-default
set qos-group 1
switch#

      Verifying Ingress Policing Configuration

      To verify Ingress Policing configuration information, perform one of the following tasks:

      Command

      Purpose
      switch# show policy-map interface [interface number]

      Displays the policy map settings for an interface or all interfaces.

      switch# show policy-map [type qos] [policy-map-name]

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

      Configuration Examples for Ingress Policing

      The following example shows the Committed Information Rate (CIR) being specified as a percentage where the Ingress Policing rate is calculated based on the port/port-channel speed:

      switch(config)# policy-map type qos pm-cos
switch(config-pmap-qos)# class cm-cos
switch(config-pmap-c-qos)# police cir percent 10 bc 20 mbytes conform transmit violate drop 
switch(config-pmap-c-qos)#

      The following example shows the output of the show policy-map command with Ingress Policing configured:

      switch(config-pmap-c-qos)# show policy-map pm-cos


  Type qos policy-maps
  ====================

  policy-map type qos pm-cos 
    class type qos cm-cos
      set qos-group 4
      police cir percent 10 bc 20 mbytes conform transmit violate drop 
    class type qos class-default
      set qos-group 1
switch(config-pmap-c-qos)#

      The following example shows a policy being applied to an interface with the service-policy command:

      switch(config)# interface ethernet 1/1
switch(config-if)# service-policy type qos input pm-cos

      The following example shows policy statistics being displayed by using the show policy-map command:

      switch(config-if)# show policy-map interface ethernet 1/1
Global statistics status :   disabled

Ethernet1/1

  Service-policy (qos) input:   qos-police
    policy statistics status:   disabled

    Class-map (qos):   qos-police (match-all)
      0 packets
      Match: dscp 10
      police cir percent 100 bc 200 ms 
        conformed 0 bytes, 0 bps action: transmit
        violated 0 bytes, 0 bps action: drop