Cisco Nexus 7000 Series NX-OS Quality of Service Configuration Guide, Release 5.x
Configuring Queuing and Scheduling
Downloads: This chapterpdf (PDF - 299.0KB) The complete bookPDF (PDF - 4.67MB) | Feedback

Configuring Queuing and Scheduling

Table Of Contents

Configuring Queuing and Scheduling

Information About Queuing and Scheduling

Setting Ingress Port CoS

Modifying Class Maps

Congestion Avoidance

Congestion Management

Virtualization Support

Licensing Requirements for Queuing and Scheduling

Prerequisites for Queuing and Scheduling

Guidelines and Limitations

Configuring Queuing and Scheduling

Configuring Ingress Port CoS

Modifying Queuing Class Maps

Configuring Congestion Avoidance

Configuring Tail Drop

Configuring WRED

Configuring Congestion Management

Configuring Bandwidth and Bandwidth Remaining

Configuring Priority

Configuring Shaping

Configuring Queue Limits

Verifying the Queuing and Scheduling Configuration

Configuration Examples for Queuing and Scheduling

Setting Ingress Port CoS Configuration Example

Priority and Queue Limit Configuration Example

Shaping and Tail Drop Configuration Example

Bandwidth and WRED Configuration Example

Feature History for Queuing


Configuring Queuing and Scheduling


This chapter describes how to configure the QoS queuing and scheduling features on the Cisco NX-OS device. This chapter includes the following sections:

Information About Queuing and Scheduling

Licensing Requirements for Queuing and Scheduling

Prerequisites for Queuing and Scheduling

Guidelines and Limitations

Configuring Queuing and Scheduling

Verifying the Queuing and Scheduling Configuration

Configuration Examples for Queuing and Scheduling

Feature History for Queuing

Information About Queuing and Scheduling

Traffic queuing is the ordering of packets and applies to both input and output of data. Device modules can support multiple queues, which you can use to control the sequencing of packets in different traffic classes. You can also set weighted random early detection (WRED) and taildrop thresholds. The device drops packets only when the configured thresholds are exceeded.

Traffic scheduling is the methodical output of packets at a desired frequency to accomplish a consistent flow of traffic. You can apply traffic scheduling to different traffic classes to weight the traffic by priority.

The queuing and scheduling processes allow you to control the bandwidth that is allocated to the traffic classes, so that you achieve the desired trade-off between throughput and latency for your network.

Table 7-1 describes the system-defined queues that you can use to perform queuing and scheduling.

Table 7-1 System-Defined Queue Types 

Queue Type
Direction
Description

2q4t

Input

2 queues with 4 WRED or tail drop thresholds per queue

1p3q4t

Output

1 strict priority plus 3 normal queues or 4 normal queues with 4 WRED or tail-drop thresholds per queue

8q2t

Input

8 queues with 2 tail drop thresholds per queue

1p7q4t

Output

1 strict priority queue plus 7 normal queues or 8 normal queues with 4 WRED or tail drop thresholds per queue


The queues match on the class of service (CoS) field. The device ensures that every CoS value from 0 to 7 maps to a queue for each queue type. Only one queue for a queue type can be assigned with a specific CoS value. For more information about the system-defined queues, see Table 3-3.

This section includes the following topics:

Setting Ingress Port CoS

Modifying Class Maps

Congestion Avoidance

Congestion Management

Virtualization Support

Setting Ingress Port CoS

You can set the CoS field in all ingress packets for untrusted ports. By default, ports are trusted and the CoS field is not modified. You can use this method to configure the port state to trusted or untrusted.

For information about configuring ingress port CoS, see the "Configuring Ingress Port CoS" section.

Modifying Class Maps

You can modify the CoS values that are matched by system-defined queuing class maps, which modify the CoS-to-queue mapping. Table 3-3 lists the default system-defined CoS values. Each CoS value appears only once in the queues of the same type.

If you want to change the system-default queuing class maps, you must also change the queuing policies applied on the interfaces because any changes in the queuing class maps causes traffic disruptions and might also cause packet drops.


Caution When you modify a system-defined queuing class map, the changes occur immediately and it may disrupt traffic on all virtual device contexts (VDCs).


Note For traffic crossing Layer 3, the queue mapping CoS-to-queue occurs automatically.


For information about configuring class maps, see the "Modifying Queuing Class Maps" section.

Congestion Avoidance

You can use the following methods to proactively avoid traffic congestion on the device:

Apply WRED to a class of traffic, which allows the device to drop packets based on the CoS field. WRED is designed to work with TCP traffic.

Apply tail drop to a class of traffic, which allows the device to drop packets based on the CoS field.

For information about configuring congestion avoidance, see the "Configuring Congestion Avoidance" section.

Congestion Management

For ingress packets, you can configure congestion management by specifying a bandwidth that allocates a minimum data rate to a queue.

For egress packets, you can choose one of the following congestion management methods:

Specify a bandwidth that allocates a minimum data rate to a queue.

Impose a maximum data rate on a class of traffic so that excess packets are retained in a queue to shape the output rate.

Allocate all data for a class of traffic to a priority queue. The device distributes the remaining bandwidth among the other queues.

For information about configuring congestion management, see the "Configuring Congestion Management" section.

Virtualization Support

A VDC is a logical representation of a set of system resources. Other than configuring class maps, queuing and scheduling apply only to the VDC where the commands are entered. For information about configuring class maps, see the "Modifying Queuing Class Maps" section.

For information about configuring VDCs, see the Cisco Nexus 7000 Series NX-OS Virtual Device Context Configuration Guide, Release 5.0.

Licensing Requirements for Queuing and Scheduling

The following table shows the licensing requirements for this feature:

Product
License Requirement

Cisco NX-OS

The QoS feature does not a require license. Any feature not included in a license package is bundled with the Cisco NX-OS system images and is provided at no extra charge to you. For a complete explanation of the Cisco NX-OS licensing scheme, see the Cisco NX-OS Licensing Guide.


However, using VDCs requires an Advanced Services license.

Prerequisites for Queuing and Scheduling

Queuing and scheduling have the following prerequisites:

You must be familiar with Chapter 3 "Using Modular QoS CLI."

You are logged on to the switch.

You are in the correct VDC. A VDC is a logical representation of a set of system resources. You can use the switchto vdc command with a VDC number.

Guidelines and Limitations

Queuing and scheduling have the following configuration guidelines and limitations:

Configure system-defined class maps with care because the changes occur immediately and traffic may be disrupted on all VDCs.

When you are working with 10-Gigabit Ethernet ports in the shared mode, the egress queuing policy applies to all the ports in the port group. With the 10-Gigabit Ethernet ports in shard mode, all the ports in the port group must be in the same VDC. For information about the shared and dedicated modes, see the Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide, Release 5.x. For information about the port groups, see the Cisco Nexus 7000 Series Hardware Installation and Reference Guide.

You cannot set either the queue limit or WRED on ingress 10-Gigabit Ethernet ports except for the 8 port 10-Gigabit Ethernet I/O module.

Configuring Queuing and Scheduling

You configure queuing and scheduling by creating policy maps of type queuing that you apply to either traffic direction of an interface. You can modify system-defined class maps, which are used in policy maps to define classes of traffic to which you want to apply policies.

Additional considerations are:

Changes to system class-maps take effect immediately across all VDCs.
The specified COS values immediately map to the new queues.

Changes are disruptive.
The traffic passing through ports of the specified port type experience a brief period of traffic loss.
All ports of the specified type are affected. For example, if you change COS-to-queue mapping for the M1 10G egress interface type, then all M1 10G ports in all VDCs experience a brief disruption.

Performance can be impacted.
If one or more ports of the specified type do not have a queuing policy applied that defines the behavior for the new queue, then the traffic mapping to that queue may experience performance degradation.

If you change the COS-to-queue mapping by modifying the queuing class-maps, then ensure that a new queuing policy was applied to all ports of that type that use the new queues.

By default, non-used queues do not have an allocated buffer. Allocate buffers to these queues to avoid tail drop.

Changes to system class-maps are only made on the default VDC.

For information about configuring policy maps and class maps, see Chapter 3 "Using Modular QoS CLI."

You can configure the congestion-avoidance features, which include tail drop and WRED, in any queue. You can configure one of the egress congestion management features, which include priority, shaping, and bandwidth in output queues, and bandwidth in input queues.

We recommend that you modify the CoS value before you create a policy map. You can modify the CoS values that are matched by device-defined class map queues. You must assign each CoS value from 0 to 7 to one or more of the queues for each queue type. Each CoS value can be used only once in each queue type.

The system-defined policy maps default-in-policy and default-out-policy are attached to all ports to which you do not apply a queuing policy map. The default policy maps cannot be configured. For more information about the default policy maps, see Table 3-5.

This example shows that if you downgrade from Release 4.0(3) to Release 4.0(2) and enter the show running-configuration command, the input default queuing policy has an unknown enum in the display:

switch# show running-config 
version 4.0(2)
...
... 
policy-map type queuing default-in-policy 
class type queuing unknown enum 0 
queue-limit percent 50 
bandwidth percent 80 
class type queuing unknown enum 0 
queue-limit percent 50 
bandwidth percent 20
 
   

If you copy and paste this configuration into any Cisco NX-OS release, the device sends errors while executing all the commands starting from the policy-map type queuing default-in-policy command. You may ignore these errors because they do not affect the performance of the device.

This section includes the following topics:

Configuring Ingress Port CoS

Modifying Queuing Class Maps

Configuring Congestion Avoidance

Configuring Congestion Management

Configuring Queue Limits

Configuring Ingress Port CoS

To make a port untrusted, set the CoS value to a static value.


NoteBy default, ports are trusted (trust CoS) and the CoS field is not modified. When you configure the ingress port CoS value, the port becomes untrusted

For the untagged bridged traffic, a Cisco Nexus 7000 Series NX-OS device ignores the Differentiated Services Code Point (DSCP) and queues on ingress and egress direction, if the CoS value is 0.

By default, Layer 3 ports trust DSCP and also copy the DSCP value to CoS.


You use the ingress default queues from the system-defined queue classes for the type of module to which you want to apply the policy map. For the list of system-defined class maps for each type of module, see Table 3-3.

The CoS values set using this procedure apply to all packet that ingress the specified interfaces, not just to the class-default packets. If you set the CoS value, the device modifies the value before ingress queuing and scheduling so the CoS-modified packets are classified differently.


Note If you want to change the system-defined queuing class-maps, you must either modify the configured queuing policies or create new queuing policies and attach these policies to the affected interfaces. If you fail to do so, you can render the default queuing or the configured queuing policies invalid, which may affect the interfaces in multiple VDCs.


SUMMARY STEPS

1. configure terminal

2. policy-map type queuing [match-first] {policy-map-name | que-dynamic}

3. class type queuing class-queuing-name

4. set cos value

5. exit

6. (Optional) show policy-map type queuing [policy-map-name | que-dynamic]

7. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

policy-map type queuing [match-first] [policy-map-name | que-dynamic]

Example:

switch(config)# policy-map type queuing untrusted_port_cos

switch(config-pmap-que)#

Configures the policy map of type queuing, and then enters policy-map mode for the policy-map name that you specify. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3 

class type queuing class-queuing-name

Example:

switch(config)# class type queuing 2q4t-in-q-default

switch(config-pmap-c-que)#

Configures the class map of type queuing, and then enters policy-map class queuing mode. Class queuing names are listed in Table 3-3.

Note To configure port CoS, you can use only an ingress default system-defined queue type.

Step 4 

set cos value

Example:

switch(config-pmap-c-que)# set cos 5

Sets the CoS field in all ingress packet to the value specified. The range is from 0 to 7.

Step 5 

exit

Example:

switch(config-cmap-que)# exit

switch(config)#

Exits policy-map queue mode, and enters configuration mode.

Step 6 

show policy-map type queuing [policy-map-name | que-dynamic]

Example:

switch(config)# show policy-map type untrusted_port_cos

(Optional) Displays information about all configured policy maps or a selected policy map of type queuing.

Step 7 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Modifying Queuing Class Maps

You can modify the CoS values that are matched by system-defined class maps. Table 3-3 lists the default system-defined CoS values.

The system-defined class maps can only be changed from the default VDC. Changes occur immediately and are applied to all ports on all VDCs that use the modified class map.


Note When you modify a system-defined class map, the changes occur immediately and may disrupt traffic on all VDCs that use the modified class map.


The device automatically modifies the CoS values that you configured in other queues so that each CoS value appears only once in the queues of the same type.

BEFORE YOU BEGIN

Ensure that you are in the default VDC for the device.

SUMMARY STEPS

1. configure terminal

2. class-map type queuing match-any {class-queuing-name | WORD}

3. match cos value-range

4. (Optional) Repeat Steps 2 and 3 to modify CoS values for additional queues

5. exit

6. (Optional) show class-map type queuing [class-queuing-name]

7. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

class-map type queuing match-any class-queuing-name

Example:

switch(config)# class-map type queuing match-any 1p3q4t-out-pq1

switch(config-cmap-que)#

Configures the class map of type queuing, and then enters class-map queuing mode. Class queuing names are listed in Table 3-3.

Note The match on WORD is used for defining hierarchical class-maps in a queuing policy. The argument, WORD, is supported only on the F-Series Modules.

Step 3 

match cos value-range

Example:

switch(config-cmap-que)# match 0-3,7

Sets the CoS value range matched by this queue. You can specify a range of values by using a hyphen between the beginning and ending values and a comma between values. The range is from 0 to 7.

Step 4 

Repeat Steps 2 and 3 to modify CoS values for additional queues.

Step 5 

exit

Example:

switch(config-cmap-que)# exit

switch(config)#

Exits class-map queue mode and enters configuration mode.

Step 6 

show class-map type queuing [class-queuing-name]

Example:

switch(config)# show class-map type queuing

(Optional) Displays information about all configured class maps or a selected class map of type queuing. Class queuing names are listed in Table 3-3.

Step 7 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Configuring Congestion Avoidance

You can configure congestion avoidance with tail drop or WRED features. Both features can be used in ingress and egress policy maps.


Note WRED and tail drop cannot be configured in the same class.


This section includes the following topics:

Configuring Tail Drop

Configuring WRED

Configuring Tail Drop

You can configure tail drop on both ingress and egress queues by setting thresholds by CoS values. The device will drop packets that exceed the thresholds. You can specify a threshold based on the queue size or buffer memory that is used by the queue.


Note You cannot configure the queue size on ingress 10-Gigabit Ethernet ports except for the 8 port 10-Gigabit Ethernet I/O module.


You use the system-defined queue classes for the type of module to which you want to apply the policy map. See Table 3-3.


Note WRED and tail drop cannot be configured in the same class.


SUMMARY STEPS

1. configure terminal

2. policy-map type queuing [match-first] {queuing-policy-map-name | que-dynamic}

3. class type queuing class-queuing-name

4. queue-limit cos value {threshold [packets | bytes | kbytes | mbytes | ms | us] | percent percent_of_queuelimit}

5. (Optional) Repeat Step 4 to assign tail drop thresholds for other CoS values.

6. (Optional) Repeat Steps 3 through 5 to assign tail drop thresholds for other queue classes.

7. exit

8. (Optional) show policy-map type queuing [policy-map-name | que-dynamic]

9. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

policy-map type queuing [match-first] [queuing-policy-map-name | que-dynamic]

Example:

switch(config)# policy-map type queuing shape_queues

switch(config-pmap-que)#

Configures the policy map of type queuing, and then enters policy-map mode for the policy-map name you specify. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3 

class type queuing class-queuing-name

Example:

switch(config)# class type queuing 1p3q4t-out-pq1

switch(config-pmap-c-que)#

Configures the class map of type queuing, and then enters policy-map class queuing mode. Class queuing names are listed in Table 3-3.

Step 4 

queue-limit cos value {threshold [packets | bytes | kbytes | mbytes | ms | us] | percent percent_of_queuelimit}

Example:

switch(config-pmap-c-que)# queue-limit cos 5 10 mbytes

Assigns a tail drop threshold based on the queue size or percentage of the buffer memory that is used by the queue. The device will drop packets that exceed the specified threshold. You can configure the threshold by the number of packets, number of bytes, or the duration of time at the underlying interface minimum guaranteed link rate. The default threshold is in packets. The size is from 1 to 83886080. The duration is from 1 to 83886080. The percentage is from 1 to 100.

The example shows how to set a tail drop threshold for packets with a CoS of 5 to a maximum size of 10 MB.

Step 5 

(Optional) Repeat Step 4 to assign tail drop thresholds for other CoS values.

Step 6 

(Optional) Repeat Steps 3 through 5 to assign tail drop thresholds for other queue classes.

Step 7 

exit

Example:

switch(config-cmap-que)# exit

switch(config)#

Exits policy-map queue mode and enters configuration mode.

Step 8 

show policy-map type queuing [policy-map-name | que-dynamic]

Example:

switch(config)# show policy-map type queuing shape_queues

(Optional) Displays information about all configured policy maps or a selected policy map of type queuing.

Step 9 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Configuring WRED

Before configuring WRED, ensure that the CoS values are there (see the "Modifying Queuing Class Maps" section).

You can configure WRED on both ingress and egress queues to set minimum and maximum packet drop thresholds. The frequency of dropped packets increases as the queue size exceeds the minimum threshold. When the maximum threshold is exceeded, all packets for the CoS value are dropped.


Note You cannot configure WRED on ingress 10-Gigabit Ethernet ports except for the 8 port 10-Gigabit Ethernet I/O module.


You can configure WRED thresholds by CoS value, and configure a single WRED threshold to use on all CoS values that you do not specifically configure.


Note WRED and tail drop cannot be configured in the same class.


You use the system-defined queue classes for the type of module to which you want to apply the policy map. See Table 3-3.

SUMMARY STEPS

1. configure terminal

2. policy-map type queuing [match-first] {queuing-policy-map-name | que-dynamic}

3. class type queuing class-queuing-name

4. random-detect cos-based [aggregate [minimum-threshold] {min-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent min-percent-of-qsize} [maximum-threshold] {max-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent max-percent-of-qsize}]

5. random-detect {cos cos-list [minimum-threshold] {min-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent min-percent-of-qsize} [maximum-threshold] {max-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent max-percent-of-qsize}}

6. (Optional) Repeat Step 5 to configure WRED for other CoS values.

7. (Optional) Repeat Steps 3 through 6 to configure WRED for other queuing classes.

8. exit

9. (Optional) show policy-map type queuing [policy-map-name | que-dynamic]

10. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

policy-map type queuing [match-first] [queuing-policy-map-name | que-dynamic]

Example:

switch(config)# policy-map type queuing shape_queues

switch(config-pmap-que)#

Configures the policy map of type queuing, and then enters policy-map mode for the policy-map name you specify. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3 

class type queuing class-queuing-name

Example:

switch(config)# class type queuing 1p3q4t-out-pq1

switch(config-pmap-c-que)#

Configures the class map of type queuing, and then enters policy-map class queuing mode. Class queuing names are listed in Table 3-3.

Step 4 

random-detect cos-based [aggregate [minimum-threshold] {min-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent min-percent-of-qsize} [maximum-threshold] {max-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent max-percent-of-qsize}]

Example 1:

switch(config-pmap-c-que)# random-detect cos-based aggregate 10 mbytes 20 mbytes

Example 2:

switch(config-pmap-c-que)# random-detect cos-based aggregate percent 10 percent 20

Configures WRED for all CoS values not configured by a CoS-specific random-detect command. You can specify minimum and maximum thresholds used to drop packets from the queue. You can configure thresholds by the number of packets, number of bytes, the duration of time at the underlying interface minimum guaranteed link rate, or as the percentage of queue size. The minimum and maximum thresholds must be of the same type. If no aggregate arguments are supplied, no aggregate WRED is configured. The default threshold is in packets. The thresholds are from 1 to 83886080. The percentage range is from 1 to 100.

Note You must enter this command, even if you enter the command with no values.

Example 1 shows how to set the aggregate WRED thresholds for nonconfigured classes of traffic to a minimum of 10 MB and a maximum of 20 MB.

Example 2 shows how to set the aggregate WRED thresholds for nonconfigured classes of traffic to a minimum of 10 percent and a maximum of 20 percent of the queue size.

Note You can specify only one random-detect cos-based command in a class.

Step 5 

random-detect {cos cos-list [[minimum-threshold] {min-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent min-percent-of-qsize}] [maximum-threshold] {max-threshold [packets | bytes | kbytes | mbytes | ms | us] | percent max-percent-of-qsize}}

Example 1:

switch(config-pmap-c-que)# random-detect cos 5,7 15 mbytes 20 mbytes

Example 2:

switch(config-pmap-c-que)# random-detect cos 5 percent 5 percent 15

(Optional) Configures WRED for specific CoS values. You can specify minimum and maximum thresholds used to drop packets from the queue. You can configure thresholds by the number of packets, number of bytes, the duration of time at the underlying interface minimum guaranteed link rate, or as the percentage of the queue size. The minimum and maximum thresholds must be of the same type. The default threshold is in packets. Thresholds are from 1 to 83886080. The percentage range is from 1 to 100.

Example 1 shows how to set the aggregate WRED thresholds for CoS values 5 and 7 to a minimum of 15 MB and a maximum of 20 MB.

Example 2 shows how to set the aggregate WRED thresholds for CoS value 5 to a minimum of 5 percent and a maximum of 15 percent of the queue size.

Step 6 

(Optional) Repeat Step 5 to configure WRED for other CoS values.

Step 7 

(Optional) Repeat Steps 3 through 6 to configure WRED for other queuing classes.

Step 8 

exit

Example:

switch(config-cmap-que)# exit

switch(config)#

Exits policy-map queue mode and enters configuration mode.

Step 9 

show policy-map type queuing [policy-map-name | que-dynamic]

Example:

switch(config)# show policy-map type queuing shape_queues

(Optional) Displays information about all configured policy maps or a selected policy map of type queuing.

Step 10 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Configuring Congestion Management

You can configure only one of the following congestion management methods in a policy map:

Allocate a minimum data rate to a queue by using the bandwidth and bandwidth remaining commands.

Allocate all data for a class of traffic to a priority queue by using the priority command. You can use the bandwidth remaining command to distribute remaining traffic among the nonpriority queues. By default, the system evenly distributes the remaining bandwidth among the nonpriority queues.

Allocate a maximum data rate to a queue by using the shape command.

In addition to the congestion management feature that you choose, you can configure one of the following queue features in each class of a policy map:

Taildrop thresholds based on the queue size and the queue limit usage. For more information, see the "Configuring Tail Drop" section.

WRED for preferential packet drops based on CoS. For more information, see the "Configuring WRED" section.

This section includes the following topics:

Configuring Bandwidth and Bandwidth Remaining

Configuring Priority

Configuring Shaping

Configuring Bandwidth and Bandwidth Remaining

You can configure the bandwidth and bandwidth remaining on both ingress and egress queues to allocate a minimum percentage of the interface bandwidth to a queue. You use the system-defined ingress or egress queue class for the type of module to which you want to apply the policy map. For the list of system-defined ingress or egress queue classes for each module, see Table 3-3.


Note If you configure bandwidth, you cannot configure the priority or shaping in the same policy map.


SUMMARY STEPS

1. configure terminal

2. policy-map type queuing [match-first] {queuing-policy-map-name | que-dynamic}

3. class type queuing class-queuing-name

4. bandwidth {rate [bps | kbps | mbps | gbps] | percent}
or
bandwidth remaining percent percent

5. (Optional) Repeat Steps 3 to 4 to assign bandwidth or bandwidth remaining for other queuing classes.

6. exit

7. (Optional) show policy-map type queuing [policy-map-name | que-dynamic]

8. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

policy-map type queuing [match-first] [queuing-policy-map-name | que-dynamic]

Example:

switch(config)# policy-map type queuing shape_queues

switch(config-pmap-que)#

Configures the policy map of type queuing, and then enters policy-map mode for the policy-map name you specify. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3 

class type queuing class-queuing-name

Example:

switch(config)# class type queuing 1p3q4t-out-pq1

switch(config-pmap-c-que)#

Configures the class map of type queuing, and then enters policy-map class queuing mode. You must select one of the system-defined output queues. Class queuing names are listed in Table 3-3.

Step 4 

bandwidth {rate [bps | kbps | mbps | gbps] | percent percent}

Example 1:

switch(config-pmap-c-que)# bandwidth 10 mbps

Example 2:

switch(config-pmap-c-que)# bandwidth percent 25

Assigns a minimum rate of the interface bandwidth to an output queue. You can configure a data rate by the bit rate or as the percentage of the underlying interface link rate. The default units are kbps. The data rate is from 1 to 10,000,000,000. The percentage range is from 1 to 100.

Note You can use only the percent keyword for interfaces set to autonegotiate.

Example 1 shows how to set the bandwidth to a minimum rate of 100 megabits per second (mbps).

Example 2 shows how to set the bandwidth to a minimum of 25 percent of the underlying link rate.

bandwidth remaining percent percent

Example:

switch(config-pmap-c-que)# bandwidth remaining percent 25

(Optional) Assigns the percentage of the bandwidth that remains to this queue. The range is from 0 to 100.

The example shows how to set the bandwidth for this queue to 25 percent of the remaining bandwidth.

Step 5 

(Optional) Repeat Steps 3 to 4 to assign bandwidth or bandwidth remaining for other queuing classes.

Step 6 

exit

Example:

switch(config-cmap-que)# exit

switch(config)#

Exits policy-map queue mode and enters configuration mode.

Step 7 

show policy-map type queuing [policy-map-name | que-dynamic]

Example:

switch(config)# show policy-map type queuing shape_queues

(Optional) Displays information about all configured policy maps or a selected policy map of type queuing.

Step 8 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Configuring Priority

If you do not specify the priority, the system-defined egress pq queues behave as normal queues. For information on the system-defined type queuing class maps, see Chapter 3 "Using Modular QoS CLI.".

You can configure only one level of priority on an egress priority queue. You use the system-defined priority queue class for the type of module to which you want to apply the policy map. For the list of available system-defined class maps for each module, see Table 3-3.

For the nonpriority queues, you can configure how much of the remaining bandwidth to assign to each queue. By default, the device evenly distributes the remaining bandwidth among the nonpriority queues.


Note If you configure priority, you cannot configure the bandwidth or shaping in the same policy map.


SUMMARY STEPS

1. configure terminal

2. policy-map type queuing [match-first] {queuing-policy-map-name | que-dynamic}

3. class type queuing class-queuing-name

4. priority [level value]

5. class type queuing class-queuing-name

6. bandwidth remaining percent percent

7. (Optional) Repeat Steps 5 to 6 to assign bandwidth remaining for the other nonpriority queues.

8. exit

9. (Optional) show policy-map type queuing [policy-map-name | que-dynamic]

10. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

policy-map type queuing [match-first] [queuing-policy-map-name | que-dynamic]

Example:

switch(config)# policy-map type queuing priority_queue1

switch(config-pmap-que)#

Configures the policy map of type queuing, and then enters policy-map mode for the policy-map name that you specify. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3 

class type queuing class-queuing-name

Example:

switch(config-pmap-que)# class type queuing 1p3q4t-out-pq1

switch(config-pmap-c-que)#

Configures the class map of type queuing, and then enters policy-map class queuing mode. You must select one of the system-defined priority queues. Class queuing names are listed in Table 3-3.

Step 4 

priority [level value]

Example:

switch(config-pmap-c-que)# priority

Selects this queue as a priority queue. Only one priority level is supported.

Step 5 

class type queuing class-queuing-name

Example:

switch(config-pmap-c-que)# class type queuing 1p3q4t-out-q2

(Optional) Configures the class map of type queuing, and then enters policy-map class queuing mode. Class queuing names are listed in Table 3-3.

Choose a nonpriority queue where you want to configure the remaining bandwidth. By default, the system evenly distributes the remaining bandwidth among the nonpriority queues.

Step 6 

bandwidth remaining percent percent

Example:

switch(config-pmap-c-que)# bandwidth remaining percent 25

(Optional) Assigns the percent of the bandwidth that remains to this queue. The range is from 1 to 100.

Step 7 

(Optional) Repeat Steps 5 to 6 to assign the remaining bandwidth for the other nonpriority queues.

Step 8 

exit

Example:

switch(config-cmap-que)# exit

switch(config)#

Exits the policy-map queue mode and enters configuration mode.

Step 9 

show policy-map type queuing [policy-map-name | que-dynamic]

Example:

switch(config)# show policy-map type queuing priority_queue1

(Optional) Displays information about all configured policy maps or a selected policy map of type queuing.

Step 10 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Configuring Shaping


Note The device forces the shape rate to the closest value in the following percentage intervals: 100, 50, 33, 25, 12.5, 6.25, 3.13, or 1.07.


You can configure shaping on an egress queue to impose a maximum rate on it. You use the system-defined egress queue class for the type of module to which you want to apply the policy map. For the list of available system-defined class maps for each module, see Table 3-3.


Note If you configure shaping, you cannot configure the bandwidth or priority in the same policy map.


SUMMARY STEPS

1. configure terminal

2. policy-map type queuing [match-first] {queuing-policy-map-name | que-dynamic}

3. class type queuing class-queuing-name

4. shape [average] {rate [bps | kbps | mbps | gbps] | percent percent}

5. (Optional) Repeat Steps 3 to 4 to configure shaping for other queuing classes.

6. exit

7. (Optional) policy-map type queuing [policy-map-name | que-dynamic]

8. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

policy-map type queuing [match-first] [queuing-policy-map-name | que-dynamic]

Example:

switch(config)# policy-map type queuing shape_queues

switch(config-pmap-que)#

Configures the policy map of type queuing, and then enters policy-map mode for the policy-map name you specify. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3 

class type queuing class-queuing-name

Example:

switch(config)# class type queuing 1p3q4t-out-pq1

switch(config-pmap-c-que)#

Configures the class map of type queuing and then enters policy-map class queuing mode. You must select one of the system-defined output queues. Class queuing names are listed in Table 3-3.

Step 4 

shape [average] {rate [bps | kbps | mbps | gbps] | percent percent}

Example 1:

switch(config-pmap-c-que)# shape 10 mbps

Example 2:

switch(config-pmap-c-que)# shape percent 25

Assigns a maximum rate on an output queue. You can configure a data rate by the bit rate or as a percentage of the underlying interface link rate. The default bit rate is in bits per second (bps). The data rate is from 8000 bps to 10 gbps. The percentage range is from 1 to 100.

Note You can use only the percent keyword for interfaces set to autonegotiate.

Example 1 shows how to shape traffic to a maximum rate of 100 megabits per second (mbps).

Example 2 shows how to shape traffic to a maximum of 25 percent of the underlying link rate.

Step 5 

(Optional) Repeat Steps 3 to 4 to configure shaping for other queuing classes.

Step 6 

exit

Example:

switch(config-cmap-que)# exit

switch(config)#

Exits policy-map queue mode and enters configuration mode.

Step 7 

show policy-map type queuing [policy-map-name | que-dynamic]

Example:

switch(config)# show policy-map type queuing shape_queues

(Optional) Displays information about all configured policy maps or a selected policy map of type queuing.

Step 8 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Configuring Queue Limits

You can configure the queue limit on both ingress and egress queues. The device drops any packets that exceed the queue limit. You use the system-defined queue classes for the type of module to which you want to apply the policy map. See Table 3-3.

SUMMARY STEPS

1. configure terminal

2. policy-map type queuing [match-first] {queuing-policy-map-name | que-dynamic}

3. class type queuing class-queuing-name

4. queue-limit {threshold [packets | bytes | kbytes | mbytes | ms | us] | percent percent_of_queuelimit}

5. exit

6. exit

7. (Optional) show policy-map type queuing [policy-map-name | que-dynamic]

8. (Optional) copy running-config startup-config

DETAILED STEPS

 
Command
Purpose

Step 1 

configure terminal

Example:

switch# configure terminal

switch(config)#

Enters configuration mode.

Step 2 

policy-map type queuing [match-first] [queuing-policy-map-name | que-dynamic]

Example:

switch(config)# policy-map type queuing shape_queues

switch(config-pmap-que)#

Configures the policy map of type queuing and then enters policy-map mode for the policy-map name you specify. Policy-map names can contain alphabetic, hyphen, or underscore characters, are case sensitive, and can be up to 40 characters.

Step 3 

class type queuing class-queuing-name

Example:

switch(config)# class type queuing 1p3q4t-out-pq1

switch(config-pmap-c-que)#

Configures the class map of type queuing and then enters policy-map class queuing mode. Class queuing names are listed in Table 3-3.

Step 4 

queue-limit {threshold [packets | bytes | kbytes | mbytes | ms | us] | percent percent_of_queuelimit}

Example:

switch(config-pmap-c-que)# queue-limit 10 mbytes

Assigns a queue limit based on the queue size or percentage of the buffer memory used by the queue. The device will drop packets that exceed the specified threshold. You can configure the threshold by the number of packets, number of bytes, or the duration of time at the underlying interface minimum guaranteed link rate. The default threshold is in packets. The size is from 1 to 83886080. The duration is from 1 to 83886080. The percentage range is from 1 to 100.

The example shows how to set a queue limit to a maximum size of 10 MB.

Step 5 

exit

Example:

switch(config-pmap-c-que)# exit

switch(config-pmap-que)#

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

Step 6 

exit

Example:

switch(config-pmap-que)# exit

switch(config)#

Exits policy-map queue mode and enters configuration mode.

Step 7 

show policy-map type queuing [policy-map-name | que-dynamic]

Example:

switch(config)# show policy-map type queuing shape_queues

(Optional) Displays information about all configured policy maps or a selected policy map of type queuing.

Step 8 

copy running-config startup-config

Example:

switch(config)# copy running-config startup-config

(Optional) Saves the running configuration to the startup configuration.

Verifying the Queuing and Scheduling Configuration

To configure queueing and scheduling, perform one of the following tasks:

Command
Purpose

show class-map type queuing [class-queuing-name]

Displays information about all configured class maps or a selected class map of type queuing. Class queuing names are listed in Table 3-3.

show policy-map type queuing [policy-map-name | que-dynamic]

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


For more information about the fields in the output from these commands, see the Cisco Nexus 7000 Series NX-OS Quality of Service Command Reference, Release 5.x.

Configuration Examples for Queuing and Scheduling

In this section you can find examples of configuring queuing and scheduling.

This section includes the following topics:

Setting Ingress Port CoS Configuration Example

Priority and Queue Limit Configuration Example

Shaping and Tail Drop Configuration Example

Bandwidth and WRED Configuration Example

Setting Ingress Port CoS Configuration Example


Note Setting the ingress port CoS value makes the specified interfaces untrusted.



Note Ensure that you are using the default queue for the port type that you are configuring. For information on the default queue for the port types, see Chapter 3 "Using Modular QoS CLI."


The following example shows how to configure ingress port CoS for 1-Gigabit Ethernet ports:

configure terminal
  policy-map type queuing untrusted_port_cos
    class type queuing 2q4t-in-q-default
      set cos 5
  interface ethernet 2/1
    service-policy type queuing input untrusted_port_cos

The following example shows how to configure ingress port CoS for 10-Gigabit Ethernet ports:

configure terminal
  policy-map type queuing untrusted_port_cos
    class type queuing 8q2t-in-q-default
      set cos 5
  interface ethernet 2/1
    service-policy type queuing input untrusted_port_cos

Priority and Queue Limit Configuration Example

The following example shows how to configure the priority and queue limit features:

configure terminal
  class-map type queuing match-any 1p3q4t-out-pq1
    match cos 5-7
  class-map type queuing match-any 1p3q4t-out-q2
    match cos 3-4
  class-map type queuing match-any 1p3q4t-out-q3
    match cos 0-2
  policy-map type queuing priority_queue1
    class type queue 1p3q4t-out-pq1
      priority
    class type queue 1p3q4t-out-q2
      bandwidth remaining percent 60
      queue-limit 1 mbytes
    class type queue 1p3q4t-out-q3
      bandwidth remaining percent 40
      queue-limit 2 mbytes

Shaping and Tail Drop Configuration Example

The following example shows how to configure the shaping and taildrop features:

configure terminal
  class-map type queuing match-any 1p3q4t-out-pq1
    match cos 5-7
  class-map type queuing match-any 1p3q4t-out-q2
    match cos 3-4
  policy-map type queuing shape_dt
    class type queue 1p3q4t-out-pq1
      shape percent 50
      queue-limit cos 5 percent 10 
      queue-limit cos 6 percent 10
    class type queue 1p3q4t-out-q2
      shape percent 25
      queue-limit cos 4 percent 15

Note If the priority keyword is not specified for a pq1 queue, the queue is considered as a normal queue, not a priority queue.


Bandwidth and WRED Configuration Example

The following example shows how to configure the bandwidth and WRED features:

configure terminal
  class-map type queuing match-any 1p3q4t-out-pq1
    match cos 5-7
  class-map type queuing match-any 1p3q4t-out-q2
    match cos 3-4
  policy-map type queuing bandwidth_wred
    class type queuing 1p3q4t-out-pq1
      bandwidth percent 50
      random-detect cosbased
      random-detect cos 5 minimum-threshold percent 10 maximum-threshold percent 30
      random-detect cos 6 minimum-threshold percent 40 maximum-threshold percent 60
    class type queuing 1p3q4t-out-q2
      bandwidth percent 25
      random-detect cos-based
      random-detect cos 4 minimum-threshold percent 20 maximum-threshold percent 40

Feature History for Queuing

Table 7-2 lists the release history for this feature.

Table 7-2 Feature History for Queuing

Feature Name
Releases
Feature Information

No change from Release 4.1(2)

5.1(1)