Class of Service (CoS) Commands

This section describes the commands you use to configure and view Class of Service (CoS) settings for the switch. The commands in this section allow you to control the priority and transmission rate of traffic.

NOTE: Commands you issue in the Interface Config mode only affect a single interface. Commands you issue in the Global Config mode affect all interfaces.

classofservice dot1p-mapping

This command maps an 802.1p priority to an internal traffic class. The <userpriority> values can range from 0-7. The <trafficclass> values range from 0-7. For more information about 802.1p priority, see Provisioning (IEEE 802.1p) Commands.

Note: This command is executed only when classofservice trust is not untrusted.Preferably the classofservices trust dot1p should be set.

• Format: classofservice dot1p-mapping <userpriority> <trafficclass>
• Modes: Global Config/ Interface Config

no classofservice dot1p-mapping

This command maps each 802.1p priority to its default internal traffic class value.

• Format: no classofservice dot1p-mapping
• Modes: Global Config/ Interface Config

classofservice ip-dscp-mapping

This command maps an IP DSCP value to an internal traffic class. The <ipdscp> value is specified as either an integer from 0 to 63, or symbolically through one of the following keywords: af11, af12, af13, af21, af22, af23, af31, af32, af33, af41, af42, af43, be, cs0, cs1, cs2, cs3, cs4, cs5, cs6, cs7, ef. The <trafficclass> values can range from 0-7, although the actual number of available traffic classes depends on the platform.

• Format: classofservice ip-dscp-mapping <ipdscp> <trafficclass>
• Mode: Global Config

no classofservice ip-dscp-mapping

This command maps each IP DSCP value to its default internal traffic class value.

• Format: no classofservice ip-dscp-mapping
• Mode: Global Config

classofservice trust

This command sets the class of service trust mode of an interface. You can set the mode to trust one of the Dot1p (802.1p) or IP DSCP packet markings. You can also set the interface mode to untrusted. If you configure an interface to use Dot1p, the mode does not appear in the output of the show running config command because Dot1p is the default.

NOTE: Use the no classofservice trust command to set the mode to the default value.

• Default: dot1p
• Format: classofservice trust {dot1p | ip-dscp | untrusted}.
• Mode: Global Config/ Interface Config

no classofservice trust

This command sets the interface mode to the default value.

• Format: no classofservice trust
• Modes: Global Config/ Interface Config

cos-queue min-bandwidth

This command specifies the minimum transmission bandwidth guarantee for each interface queue. The total number of queues supported per interface is platform specific. A value from 0-100 (percentage of respective port capacity) must be specified for each supported queue, with 0 indicating no guaranteed minimum bandwidth. The sum of all values entered must not exceed 100.

• Format: cos-queue min-bandwidth <bw-0> <bw-1> … <bw-n>
• Modes: Global Config/ Interface Config

no cos-queue min-bandwidth

This command restores the default for each queue's minimum bandwidth value.

• Format: no cos-queue min-bandwidth
• Modes: Global Config/ Interface Config

cos-queue random-detect

This command activates weighted random early discard (WRED) for each specified queue on the interface. Specific WRED parameters are configured using the random-detect queue-parms and the random-detect exponential-weighting-constant commands.

• Format: cos-queue random-detect queue-id-1 [queue-id-2 … queue-id-n]
• Mode: Global Config/Interface Config

When specified in Interface Config mode, this command affects a single interface only, whereas in Global Config mode, it applies to all interfaces. At least one, but no more than n, queue-id values are specified with this command. Duplicate queue-id values are ignored. Each queue-id value ranges from 0 to (n-1), where n is the total number of queues supported per interface. The number n is platform dependent and corresponds to the number of supported queues (traffic classes).

no cos-queue random-detect

Use this command to disable WRED, thereby restoring the default tail drop operation for the specified queues on the interface.

• Format: no cos-queue random-detect {queue-id-1 [queue-id-2 … queue-id-n]}
• Mode: Global Config/Interface Config

cos-queue strict

This command activates the strict priority scheduler mode for each specified queue.

• Format: cos-queue strict <queue-id-1> [<queue-id-2> … <queue-id-n>]
• Modes: Global Config/ Interface Config

no cos-queue strict

This command restores the default weighted scheduler mode for each specified queue.

• Format: no cos-queue strict {<queue-id-1> [<queue-id-2> … <queue-id-n>]}
• Modes: Global Config/ Interface Config

random-detect

This command is used to enable WRED for the interface/global as a whole, and is only available when per-queue WRED activation control is not supported by the device Specific WRED parameters are configured using the random-detect queue-parms and the random-detect exponential-weighting-constant commands.

• Format: random-detect
• Mode: Global Config/Interface Config

When specified in Interface Config mode, this command affects a single interface only, whereas in Global Config mode, it applies to all interfaces. The Interface Config mode command is only available on platforms that support independent per-port class of service queue configuration.

no random-detect

Use this command to disable WRED, thereby restoring the default tail drop operation for all queues on the interface.

• Format: no random-detect
• Mode: Global Config/Interface Config

random-detect exponential weighting-constant

This command is used to configure the WRED decay exponent for a CoS queue interface/global.

• Format: random-detect exponential-weighting-constant 1-TBDFormat
• Mode: Global Config/Interface Config

random-detect queue-parms

This command is used to configure WRED parameters for each drop precedence level supported by a queue. It is used only when per-COS queue configuration is enabled (using the cos-queue random-detect command).

• Format: random-detect queue-parms {queue-id-1 [queue-id-2 ... queue-id-n] min-thresh threshprec-1 ... thresh-prec-n max-thresh thresh-prec-1 ... thresh-prec-n drop-probability prob-prec-1 ... prob-prec-n}
• Mode: Global Config/Interface Config
• min-thresh: The minimum threshold the queue depth (as a percentage) where WRED starts marking and dropping traffic.
• max-thresh: The maximum threshold is the queue depth (as a percentage) above which WRED marks/drops all traffic.
• drop-probability: The percentage probability that WRED will mark/drop a packet, when the queue depth is at the maximum threshold. (The drop probability increases linearly from 0 just before the minimum threshold, to this value at the maximum threshold, then goes to 100% for larger queue depths).

Each parameter is specified for each possible drop precedence (color of TCP traffic). The last precedence applies to all non-TCP traffic. For example, in a 3-color system, four of each parameter specified: green TCP, yellow TCP, red TCP, and non-TCP, respectively

no random-detect queue-parms

Use this command to set the WRED configuration back to the default.

• Format: no random-detect queue-parms {queue-id-1 [queue-id-2 .. queue-id-n]}
• Modes: Global Config/Interface Config

traffic-shape

This command specifies the maximum transmission bandwidth limit for the interface as a whole. Also known as rate shaping, traffic shaping has the effect of smoothing temporary traffic bursts over time so that the transmitted traffic rate is bounded.

• Format: traffic-shape <bw>
• Modes: Global Config/ Interface Config

no traffic-shape

This command restores the interface shaping rate to the default value.

• Format: no traffic-shape
• Modes:Global Config/ Interface Config

show classofservice dot1p-mapping

This command displays the current Dot1p (802.1p) priority mapping to internal traffic classes for a specific interface. The <unit/slot/port> parameter is optional. If specified, the 802.1p mapping table of the interface is displayed. If omitted, the most recent global configuration settings are displayed. For more information, see Provisioning (IEEE 802.1p) Commands.

• Format: show classofservice dot1p-mapping [<unit/slot/port>]
• Mode: Privileged EXEC

The display parameters for above command are:

• User Priority: The 802.1p user priority value.
• Traffic Class: The traffic class internal queue identifier to which the user priority value is mapped.

show classofservice ip-precedence-mapping

This command displays the current IP Precedence mapping to internal traffic classes for a specific interface. The unit/slot/port parameter is optional. If specified, the IP Precedence mapping table of the interface is displayed. If omitted, the most recent global configuration settings are displayed.

• Format: show classofservice ip-precedence-mapping [<unit/slot/port>]
• Mode: Privileged EXEC

The display parameters for above command are:

• IP Precedence: The IP Precedence value.
• Traffic Class: The traffic class internal queue identifier to which the IP Precedence value is mapped.

show classofservice ip-dscp-mapping

This command displays the current IP DSCP mapping to internal traffic classes for the global configuration settings.

• Format: show classofservice ip-dscp-mapping
• Mode: Privileged EXEC

The display parameters for above command are:

• IP DSCP: The IP DSCP value.
• Traffic Class:The traffic class internal queue identifier to which the IP DSCP value is mapped.

show classofservice trust

This command displays the current trust mode setting for a specific interface. The <unit/slot/ port> parameter is optional. If you specify an interface, the command displays the port trust mode of the interface. If you do not specify an interface, the command displays the most recent global configuration settings.

• Format: show classofservice trust [<unit/slot/port>]
• Mode: Privileged EXEC

The display parameters for above command are:

• Non-IP Traffic Class: The traffic class used for non-IP traffic. This is only displayed when the COS trust mode is set to trust IP Precedence or IP DSCP.
• Untrusted Traffic Class: The traffic class used for all untrusted traffic. This is only displayed when the COS trust mode is set to 'untrusted'.

show interfaces cos-queue

This command displays the class-of-service queue configuration for the specified interface. The unit/slot/port parameter is optional. If specified, the class-of-service queue configuration of the interface is displayed. If omitted, the most recent global configuration settings are displayed.

• Format: show interfaces cos-queue [<unit/slot/port>]
• Mode: Privileged EXEC

The display parameters for above command are:

• Queue Id: Queue Id: An interface supports n queues numbered 0 to (n-1). The value of n is 8.
• Minimum Bandwidth: minimum transmission bandwidth guarantee for the queue, expressed as a percentage 0 to 100. A value of 0 means bandwidth is not guaranteed and the queue operates using best-effort. This is a configured value.
• Scheduler Type: Indicates whether this queue is scheduled for transmission using a strict priority or a weighted scheme. This is a configured value.
• Queue Management Type: queue depth management technique used for this queue (tail drop/WRED).

If you specify the interface, the command also displays the following information.

• Interface: The unit/slot/port of the interface. If displaying the global configuration, this output line is replaced with a Global Config indication.
• Interface Shaping Rate: The maximum transmission bandwidth limit for the interface as a whole. It is independent of any per-queue maximum bandwidth value(s) in effect for the interface. This is a configured value.

show interfaces random-detect

This command displays the global WRED settings for each CoS queue. If you specify the slot/port, the command displays the WRED settings for each CoS queue on the specified interface.

• Format: show interfaces random-detect [unit/slot/port]
• Mode: Privileged EXEC

The display parameters for above command are:

• Queue ID: An interface supports n queues numbered 0 to (n-1). The specific n value is platform dependent.
• WRED Minimum Threshold: The configured minimum threshold the queue depth (as a percentage) where WRED starts marking and dropping traffic.
• WRED Maximum Threshold: The configured maximum threshold is the queue depth (as a percentage) above which WRED marks / drops all traffic.
• WRED Drop Probability: The configured percentage probability that WRED will mark/drop a packet, when the queue depth is at the maximum threshold. (The drop probability increases linearly from 0 just before the minimum threshold, to this value at the maximum threshold, then goes to 100% for larger queue depths).