Quality of Service
Cisco UCS provides the following methods to implement quality of service:
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System classes that specify the global configuration for certain types of traffic across the entire system
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QoS policies that assign system classes for individual vNICs
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Flow control policies that determine how uplink Ethernet ports handle pause frames
Global QoS changes made to the QoS system class may result in brief data-plane interruptions for all traffic. Some examples of such changes are:
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Changing the MTU size for an enabled class
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Changing packet drop for an enabled class
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Changing the CoS value for an enabled class
Guidelines and Limitations for Quality of Service on Cisco UCS 6300 Series Fabric Interconnect
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Cisco UCS 6300 Series Fabric Interconnect uses a shared buffer for all system classes.
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Multicast optimization is not supported.
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When you change the QoS parameters for any class causes traffic disruption to all classes. The following table lists the changes in the QoS system class and the conditions that trigger a system reboot.
QoS System class status
Condition
FI Reboot Status
Enabled
Change between drop and no drop
Yes
No-drop
Change between enable and disable
Yes
Enable and no-drop
Change in MTU size
Yes
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The subordinate FI reboots first as a result of the change in the QoS system class , followed by the primary FI.
Note
Cisco UCS Manager displays a prompt that the fabric interconnect will reboot when the system policy is changed.
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show queuing interface command is not supported.
Guidelines and Limitations for Quality of Service on Cisco UCS Mini
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Cisco UCS Mini uses a shared buffer for all system classes.
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The bronze class shares the buffer with SPAN. We recommend using either SPAN or the bronze class.
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Multicast optimization is not supported.
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Changing the QoS parameters for any class causes traffic disruption to all classes.
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When mixing Ethernet and FC or FCoE traffic, the bandwidth distribution is not equal.
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Multiple streams of traffic from the same class may not be distributed equally.
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Use the same CoS values for all no-drop policies to avoid any FC or FCoE performance issues.
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Only the platinum and gold classes support no-drop policies.
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show queuing interface command is not supported.