Cisco UCS Manager CLI Configuration Guide, Release 2.0
Configuring Quality of Service
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Configuring Quality of Service

Configuring Quality of Service

This chapter includes the following sections:

Quality of Service

Cisco UCS provides the following methods to implement quality of service:

  • System classes that specify the global configuration for certain types of traffic across the entire system
  • QoS policies that assign system classes for individual vNICs
  • Flow control policies that determine how uplink Ethernet ports handle pause frames

Configuring System Classes

System Classes

Cisco UCS uses Data Center Ethernet (DCE) to handle all traffic inside a Cisco UCS domain. This industry standard enhancement to Ethernet divides the bandwidth of the Ethernet pipe into eight virtual lanes. Two virtual lanes are reserved for internal system and management traffic. You can configure quality of service for the other six virtual lanes. System classes determine how the DCE bandwidth in these six virtual lanes is allocated across the entire Cisco UCS domain.

Each system class reserves a specific segment of the bandwidth for a specific type of traffic. This provides a level of traffic management, even in an oversubscribed system. For example, you can configure the Fibre Channel Priority system class to determine the percentage of DCE bandwidth allocated to FCoE traffic.

The following table describes the system classes that you can configure:

Table 1 System Classes

System Class

Description

Platinum

Gold

Silver

Bronze

A configurable set of system classes that you can include in the QoS policy for a service profile. Each system class manages one lane of traffic.

All properties of these system classes are available for you to assign custom settings and policies.

Best Effort

A system class that sets the quality of service for the lane reserved for Basic Ethernet traffic.

Some properties of this system class are preset and cannot be modified. For example, this class has a drop policy that allows it to drop data packets if required. You cannot disable this system class.

Fibre Channel

A system class that sets the quality of service for the lane reserved for Fibre Channel over Ethernet traffic.

Some properties of this system class are preset and cannot be modified. For example, this class has a no-drop policy that ensures it never drops data packets. You cannot disable this system class.

Configuring a System Class

The type of adapter in a server may limit the maximum MTU supported. For example, network MTU above the maximums may cause the packet to be dropped for the following adapters:

  • The Cisco UCS M71KR CNA adapter, which supports a maximum MTU of 9216.
  • The Cisco UCS 82598KR-CI adapter, which supports a maximum MTU of 14000.
Procedure
      Command or Action Purpose
    Step 1 UCS-A# scope eth-server  

    Enters Ethernet server mode.

     
    Step 2 UCS-A /eth-server # scope qos  

    Enters Ethernet server QoS mode.

     
    Step 3 UCS-A /eth-server/qos # scope eth-classified {bronze | gold | platinum silver}  

    Enters Ethernet server QoS Ethernet classified mode for the specified system class.

     
    Step 4 UCS-A /eth-server/qos/eth-classified # enable  

    Enables the specified system class.

     
    Step 5 UCS-A /eth-server/qos/eth-classified # set cos cos-value  

    Specifies the class of service for the specified system class. Valid class of service values are 0 to 6; higher values indicate more important traffic.

     
    Step 6 UCS-A /eth-server/qos/eth-classified # set drop {drop | no-drop}  
    Specifies whether the channel can drop packets or not.
    Note   

    Only one system class can use the no-drop option.

     
    Step 7 UCS-A /eth-server/qos/eth-classified # set mtu {mtu-value | fc | normal}  

    The maximum transmission unit, or packet size, that this vNIC accepts.

    Note   

    If the vNIC has an associated QoS policy, the MTU specified here must be equal to or less than the MTU specified in the associated QoS system class. If this MTU value exceeds the MTU value in the QoS system class, packets may be dropped during data transmission.

     
    Step 8 UCS-A /eth-server/qos/eth-classified # set multicast-optimize {no | yes}  

    Specifies whether the class is optimized to for sending multicast packets.

     
    Step 9 UCS-A /eth-server/qos/eth-classified # set weight {weight-value | best-effort | none}  

    Specifies the relative weight for the specified system class. Valid weight values are 0 to 10.

     
    Step 10 UCS-A /eth-server/qos/eth-classified # commit-buffer  

    Commits the transaction to the system configuration.

     

    The following example enables the platinum system class, allows the channel to drop packets, sets the class of service to 6, sets the MTU to normal, optimizes the class for sending multicast packets, sets the relative weight to 5, and commits the transaction:

    UCS-A# scope eth-server
    UCS-A /eth-server # scope qos
    UCS-A /eth-server/qos # scope eth-classified platinum
    UCS-A /eth-server/qos/eth-classified # enable
    UCS-A /eth-server/qos/eth-classified* # set drop drop
    UCS-A /eth-server/qos/eth-classified* # set cos 6
    UCS-A /eth-server/qos/eth-classified* # set mtu normal
    UCS-A /eth-server/qos/eth-classified* # set multicast-optimize yes
    UCS-A /eth-server/qos/eth-classified* # set weight 5
    UCS-A /eth-server/qos/eth-classified* # commit-buffer
    UCS-A /eth-server/qos/eth-classified # 
    

    Disabling a System Class

    If you disable a system class that is used in a QoS policy, Cisco UCS Manager uses the system class configured with CoS 0 for traffic on servers that are configured with the QoS policy. If no system class is configured as CoS 0, the Best Effort system class is used. You cannot disable the Best Effort or Fibre Channel system classes.

    Procedure
        Command or Action Purpose
      Step 1 UCS-A# scope eth-server  

      Enters Ethernet server mode.

       
      Step 2 UCS-A /eth-server # scope qos  

      Enters Ethernet server QoS mode.

       
      Step 3 UCS-A /eth-server/qos # scope eth-classified {bronze | gold | platinum silver}  

      Enters Ethernet server QoS Ethernet classified mode for the specified system class.

       
      Step 4 UCS-A /eth-server/qos/eth-classified # disable  

      Disables the specified system class.

       
      Step 5 UCS-A /eth-server/qos/eth-classified # commit-buffer  

      Commits the transaction to the system configuration.

       

      The following example disables the platinum system class and commits the transaction:

      UCS-A# scope eth-server
      UCS-A /eth-server # scope qos
      UCS-A /eth-server/qos # scope eth-classified platinum
      UCS-A /eth-server/qos/eth-classified # disable
      UCS-A /eth-server/qos/eth-classified* # commit-buffer
      UCS-A /eth-server/qos/eth-classified # 
      

      Configuring Quality of Service Policies

      Quality of Service Policy

      A quality of service (QoS) policy assigns a system class to the outgoing traffic for a vNIC or vHBA. This system class determines the quality of service for that traffic. For certain adapters you can also specify additional controls on the outgoing traffic, such as burst and rate.

      You must include a QoS policy in a vNIC policy or vHBA policy and then include that policy in a service profile to configure the vNIC or vHBA.

      Configuring a QoS Policy

      Procedure
          Command or Action Purpose
        Step 1 Switch-A# scope org org-name  

        Enters org mode for the specified organization. To enter the default org mode, type / as the org-name .

         
        Step 2 Switch-A /org # create qos-policy policy-name  

        Creates the specified QoS policy, and enters org QoS policy mode.

         
        Step 3 Switch-A /org/qos-policy # create egress-policy  

        Creates the egress policy (for both vNICs and vHBAs) to be used by the QoS policy, and enters org QoS policy egress policy mode.

         
        Step 4 Switch-A /org/qos-policy/egress-policy # set host-cos-control {full | none}  

        (Optional) Specifies whether the host or Cisco UCS Manager controls the class of service (CoS).

        Use the full keyword to have the host control the CoS. If the packet has a valid CoS value, the host uses that value. Otherwise, it uses the CoS value associated with the specified class priority. Use the none keyword to have Cisco UCS Manager use the CoS value associated with the specified priority.

         
        Step 5 Switch-A /org/qos-policy/egress-policy # set prio sys-class-name  

        Specifies the system class to be used for the egress policy. The sys-class-name argument can be one of the following class keywords:

        • Fc—Use this priority for QoS policies that control vHBA traffic only.
        • Platinum—Use this priority for QoS policies that control vNIC traffic only.
        • Gold—Use this priority for QoS policies that control vNIC traffic only.
        • Silver—Use this priority for QoS policies that control vNIC traffic only.
        • Bronze—Use this priority for QoS policies that control vNIC traffic only.
        • Best Effort—Do not use this priority. It is reserved for the Basic Ethernet traffic lane. If you assign this priority to a QoS policy and configure another system class as CoS 0, Cisco UCS Manager does not default to this system class. It defaults to the priority with CoS 0 for that traffic.
         
        Step 6 Switch-A /org/qos-policy/egress-policy # set rate {line-rate | kbps} burst bytes  

        Specifies the rate limit for egress traffic by defining the average traffic rate and burst size. The line-rate keyword sets the rate limit to the physical line rate.

        Rate limiting is not applicable to all adapters. For example, this setting is not supported on the Cisco UCS M82-8P Virtual Interface Card.

         
        Step 7 Switch-A /org/qos-policy/egress-policy # committ-buffer  

        Commits the transaction to the system configuration.

         

        The following example creates a QoS policy for vNIC traffic, assigns the platinum system class and sets the rate limit (traffic rate and burst size) for the egress policy, and commits the transaction:

        Switch-A# scope org /
        Switch-A /org # create qos-policy VnicPolicy34
        Switch-A /org/qos-policy* # create egress-policy
        Switch-A /org/qos-policy/egress-policy* # set prio platinum
        Switch-A /org/qos-policy/egress-policy* # set rate 5000000 burst 65000
        Switch-A /org/qos-policy/egress-policy* # commit-buffer
        Switch-A /org/qos-policy/egress-policy # 
        

        The following example creates a QoS policy for vHBA traffic, assigns the fc (Fibre Channel) system class and sets the rate limit (traffic rate and burst size) for the egress policy, and commits the transaction:

        Switch-A# scope org /
        Switch-A /org # create qos-policy VhbaPolicy12
        Switch-A /org/qos-policy* # create egress-policy
        Switch-A /org/qos-policy/egress-policy* # set prio fc
        Switch-A /org/qos-policy/egress-policy* # set rate 5000000 burst 65000
        Switch-A /org/qos-policy/egress-policy* # commit-buffer
        Switch-A /org/qos-policy/egress-policy # 
        
        What to Do Next

        Include the QoS policy in a vNIC or vHBA template.

        Deleting a QoS Policy

        If you delete a QoS policy that is in use or you disable a system class that is used in a QoS policy, any vNIC or vHBA that uses that QoS policy is assigned to the Best Effort system class or to the system class with a CoS of 0. In a system that implements multi-tenancy, Cisco UCS Manager first attempts to find a matching QoS policy in the organization hierarchy.

        Procedure
            Command or Action Purpose
          Step 1 UCS-A# scope org org-name  

          Enters organization mode for the specified organization. To enter the root organization mode, type / as the org-name.

           
          Step 2 UCS-A /org # delete qos-policy policy-name  

          Deletes the specified QoS policy.

           
          Step 3 UCS-A /org # commit-buffer  

          Commits the transaction to the system configuration.

           

          The following deletes the QoS policy named QosPolicy34 and commits the transaction:

          UCS-A# scope org /
          UCS-A /org # delete qos-policy QosPolicy34
          UCS-A /org* # commit-buffer
          UCS-A /org #
          

          Configuring Flow Control Policies

          Flow Control Policy

          Flow control policies determine whether the uplink Ethernet ports in a Cisco UCS domain send and receive IEEE 802.3x pause frames when the receive buffer for a port fills. These pause frames request that the transmitting port stop sending data for a few milliseconds until the buffer clears.

          For flow control to work between a LAN port and an uplink Ethernet port, you must enable the corresponding receive and send flow control parameters for both ports. For Cisco UCS, the flow control policies configure these parameters.

          When you enable the send function, the uplink Ethernet port sends a pause request to the network port if the incoming packet rate becomes too high. The pause remains in effect for a few milliseconds before traffic is reset to normal levels. If you enable the receive function, the uplink Ethernet port honors all pause requests from the network port. All traffic is halted on that uplink port until the network port cancels the pause request.

          Because you assign the flow control policy to the port, changes to the policy have an immediate effect on how the port reacts to a pause frame or a full receive buffer.

          Configuring a Flow Control Policy

          Before You Begin

          Configure the network port with the corresponding setting for the flow control that you need. For example, if you enable the send setting for flow-control pause frames in the policy, make sure that the receive parameter in the network port is set to on or desired. If you want the Cisco UCS port to receive flow-control frames, make sure that the network port has a send parameter set to on or desired. If you do not want to use flow control, you can set the send and receive parameters on the network port to off.

          Procedure
              Command or Action Purpose
            Step 1 UCS-A# scope eth-uplink  

            Enters Ethernet uplink mode.

             
            Step 2 UCS-A /eth-uplink # scope flow-control  

            Enters Ethernet uplink flow control mode.

             
            Step 3 UCS-A /eth-uplink/flow-control # create policy policy-name  

            Creates the specified flow control policy.

             
            Step 4 UCS-A /eth-uplink/flow-control/policy # set prio prio-option  

            Specifies one of the following flow control priority options:

            • auto —The Cisco UCS system and the network negotiate whether PPP will be used on this fabric interconnect.
            • on —PPP is enabled on this fabric interconnect.
             
            Step 5 UCS-A /eth-uplink/flow-control/policy # set receive receive-option  

            Specifies one of the following flow control receive options:

            • off —Pause requests from the network are ignored and traffic flow continues as normal.
            • on —Pause requests are honored and all traffic is halted on that uplink port until the network cancels the pause request.
             
            Step 6 UCS-A /eth-uplink/flow-control/policy # set send send-option  

            Specifies one of the following flow control send options:

            • off —Traffic on the port flows normally regardless of the packet load.
            • on —The Cisco UCS system sends a pause request to the network if the incoming packet rate becomes too high. The pause remains in effect for a few milliseconds before traffic is reset to normal levels.
             
            Step 7 UCS-A /org/qos-policy/vnic-egress-policy # commit-buffer  

            Commits the transaction to the system configuration.

             

            The following configures a flow control policy and commits the transaction:

            UCS-A# scope eth-uplink
            UCS-A /eth-uplink # scope flow-control
            UCS-A /eth-uplink/flow-control # create policy FlowControlPolicy23
            UCS-A /eth-uplink/flow-control/policy* # set prio auto
            UCS-A /eth-uplink/flow-control/policy* # set receive on
            UCS-A /eth-uplink/flow-control/policy* # set send on
            UCS-A /eth-uplink/flow-control/policy* # commit-buffer
            UCS-A /eth-uplink/flow-control/policy #
            
            What to Do Next

            Associate the flow control policy with an uplink Ethernet port or port channel.

            Deleting a Flow Control Policy

            Procedure
                Command or Action Purpose
              Step 1 UCS-A# scope eth-uplink  

              Enters Ethernet uplink mode.

               
              Step 2 UCS-A /eth-uplink # scope flow-control  

              Enters Ethernet uplink flow control mode.

               
              Step 3 UCS-A /eth-uplink/flow-control # delete policy policy-name  

              Deletes the specified flow control policy.

               
              Step 4 UCS-A /eth-uplink/flow-control # commit-buffer  

              Commits the transaction to the system configuration.

               

              The following example deletes the flow control policy named FlowControlPolicy23 and commits the transaction:

              UCS-A# scope eth-uplink
              UCS-A /eth-uplink # scope flow-control
              UCS-A /eth-uplink/flow-control # delete policy FlowControlPolicy23
              UCS-A /eth-uplink/flow-control* # commit-buffer
              UCS-A /eth-uplink/flow-control #