Cisco Nexus 5000 NX-OS Service Configuration Manual

Cisco Nexus 5000 NX-OS Quality of Service Configuration Guide, Release 5.1(3)N2(1)

First Published: March 13, 2012

Last Modified: February 12, 2013

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Text Part Number: OL-26657-01

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CONTENTS

Preface

CHAPTER 1

CHAPTER 2

CHAPTER 3

Preface vii

Audience vii

Document Conventions vii

Documentation Feedback viii

Obtaining Documentation and Submitting a Service Request ix

New and Changed Information 1

New and Changed Information for this Release 1

Overview 3

Information About Quality of Service 3

Modular QoS CLI 3

QoS for Traffic Directed to the CPU 5

Configuring Classification 7

Information About Classification 7

Ingress Classification Policies 8

Licensing Requirements for Classification 8

Configuring Classification 8

Configuring Class Maps 8

Configuring CoS Classification 9

Configuring Precedence Classification 10

Configuring DSCP Classification 12

Configuring Protocol Classification 13

Configuring IP RTP Classification 14

Configuring ACL Classification 15

Verifying the Classification Configuration 16

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Contents

CHAPTER 4

CHAPTER 5

Configuring Policy Maps 17

Information About Policy Types 17

Configuring Policy Maps 19

Creating Policy Maps 19

Configuring Type QoS Policies 21

Configuring Type Network QoS Policies 22

Configuring Type Queuing Policies 23

Verifying the Policy Map Configuration 24

Configuring Marking 27

Information About Marking 27

Configuring Marking 27

Configuring DSCP Marking 27

Configuring IP Precedence Marking 29

Configuring CoS Marking 30

Required CoS Marking Configuration in a Layer 3 Topology 31

CHAPTER 6

CHAPTER 7

Verifying the Marking Configuration 32

Configuring QoS on the System 35

Information About System Classes 35

System Classes 35

Default System Classes 35

MTU 36

Configuring System QoS 37

Attaching the System Service Policy 37

Restoring the Default System Service Policies 38

Configuring the Queue Limit for a Specified Fabric Extender 39

Enabling the Jumbo MTU 40

Verifying the Jumbo MTU 41

Verifying the System QoS Configuration 41

Configuring QoS on Interfaces 43

Information About Interface QoS 43

Trust Boundaries 43

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Contents

Policy for Fibre Channel Interfaces 44

QoS for Multicast Traffic 44

Configuring Interface QoS 45

Configuring Untagged CoS 45

Configuring an Interface Service Policy 45

Configuring a Service Policy for a Layer 3 Interface 46

Verifying the Interface QoS Configuration 47

CHAPTER 8

Configuring QoS on VLANs 49

Information About VLAN QoS 49

Precedence of QoS Policies 49

Example of Interface, System, and VLAN Policy Precedence 50

Example of Interface and System QoS Policy Precedence 50

Example of System and VLAN Policy Precedence 50

Example of VLAN QoS and VACL Policy Precedence 51

Limiting TCAM Entries for VLAN QoS 52

Guidelines and Limitations for VLAN QoS 52

Configuring VLAN QoS 53

Configuring or Changing the Interface QoS TCAM Limit 53

Removing the Interface QoS Limit from the TCAM 54

Configuring a Service Policy on a VLAN 54

Removing a Service Policy from a VLAN 55

Verifying the VLAN QoS Configuration 56

Feature History for VLAN QoS 56

CHAPTER 9

Configuring Queuing and Flow Control 57

Information About Queues 57

Ingress Queuing Policies 57

Egress Queuing Policies 57

Buffering and Queue Limits on the Cisco Nexus 5000 Platform 58

Buffering and Queue Limits on the Cisco Nexus Device 59

Information About Flow Control 60

Link-Level Flow Control 60

Priority Flow Control 60

Configuring Queuing 61

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Contents

Configuring the Queue Limit for a Specified Fabric Extender 61

Configuring No-Drop Buffer Thresholds 62

Configuring the Buffer Threshold for the Cisco Nexus 2148T Fabric Extender 63

Enabling Virtual Output Queuing Limits for Unicast Traffic on the Cisco Nexus Device 64

Configuring Flow Control 65

Link-Level Flow Control 65

Configuring Priority Flow Control 65

Configuring Link-Level Flow Control 66

Disabling Slow Port Pruning on Multicast Traffic on the Cisco Nexus 5500 Series

Device 66

Verifying the Queue and Flow Control Configurations 67

CHAPTER 10

QoS Configuration Examples 69

QoS Example 1 69

QoS Example 2 70

QoS Example 3 72

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Preface

The Preface contains the following sections:

Audience, page vii

•

Document Conventions, page vii

•

Documentation Feedback, page viii

•

Obtaining Documentation and Submitting a Service Request, page ix

•

Audience

This publication is for network administrators who configure and maintain Cisco Nexus devices and Cisco
Nexus 2000 Series Fabric Extenders.

Document Conventions

Command descriptions use the following conventions:

DescriptionConvention

bold

Italic

[x | y]

{x | y}

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Bold text indicates the commands and keywords that you enter literally
as shown.

Italic text indicates arguments for which the user supplies the values.

Square brackets enclose an optional element (keyword or argument).[x]

Square brackets enclosing keywords or arguments separated by a vertical
bar indicate an optional choice.

Braces enclosing keywords or arguments separated by a vertical bar
indicate a required choice.

Documentation Feedback

Preface

DescriptionConvention

[x {y | z}]

Nested set of square brackets or braces indicate optional or required
choices within optional or required elements. Braces and a vertical bar
within square brackets indicate a required choice within an optional
element.

variable

Indicates a variable for which you supply values, in context where italics
cannot be used.

string

A nonquoted set of characters. Do not use quotation marks around the
string or the string will include the quotation marks.

Examples use the following conventions:

DescriptionConvention

Terminal sessions and information the switch displays are in screen font.screen font

Information you must enter is in boldface screen font.boldface screen font

italic screen font

Arguments for which you supply values are in italic screen font.

Nonprinting characters, such as passwords, are in angle brackets.< >

Default responses to system prompts are in square brackets.[ ]

!, #

This document uses the following conventions:

Note

Means reader take note. Notes contain helpful suggestions or references to material not covered in the
manual.

Caution

Means reader be careful. In this situation, you might do something that could result in equipment damage
or loss of data.

Documentation Feedback

To provide technical feedback on this document, or to report an error or omission, please send your comments
to: [e-mail].

We appreciate your feedback.

An exclamation point (!) or a pound sign (#) at the beginning of a line
of code indicates a comment line.

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Preface

Obtaining Documentation and Submitting a Service Request

Obtaining Documentation and Submitting a Service Request

For information on obtaining documentation, using the Cisco Bug Search Tool (BST), submitting a service
request, and gathering additional information, see What's New in Cisco Product Documentation, at: http://

www.cisco.com/c/en/us/td/docs/general/whatsnew/whatsnew.html.

Subscribe to What's New in Cisco Product Documentation, which lists all new and revised Cisco technical
documentation as an RSS feed and delivers content directly to your desktop using a reader application. The
RSS feeds are a free service.

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Obtaining Documentation and Submitting a Service Request

Preface

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CHAPTER 1

New and Changed Information

This chapter contains the following sections:

New and Changed Information for this Release, page 1

•

New and Changed Information for this Release

The following table provides an overview of the significant changes to this guide for this current release. The
table does not provide an exhaustive list of all changes made to the configuration guide or of the new features
in this release.

Where DocumentedDescriptionFeature

Support for QoS VLANs.VLAN QoS

Configuring QoS on VLANs, on
page 49

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New and Changed Information for this Release

New and Changed Information

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Overview

This chapter contains the following sections:

Information About Quality of Service, page 3

•

Modular QoS CLI, page 3

•

QoS for Traffic Directed to the CPU , page 5

•

Information About Quality of Service

The configurable Cisco NX-OS quality of service (QoS) features allow you to classify the network traffic,
prioritize the traffic flow, and provide congestion avoidance.

The default QoS configuration on the device provides lossless service for Fibre Channel and Fibre Channel
over Ethernet (FCoE) traffic and best-effort service for Ethernet traffic. QoS can be configured to provide
additional classes of service for Ethernet traffic. Cisco NX-OS QoS features are configured using Cisco
Modular QoS CLI (MQC).

Standard Ethernet is a best-effort medium which means that it lacks any form of flow control. In the event of
congestion or collisions, Ethernet will drop packets. The higher level protocols detect the missing data and
retransmit the dropped packets.

Fibre Channel requires a reliable transport system that guarantees the delivery of every packet. To properly
support FCoE, Ethernet has been enhanced with a priority flow control (PFC) mechanism to prevent congestion.

The FCoE QoS must be configured either if native FC or FCoE or FC and FCoE are in use. The FCoE QoS
must be added even if Ethernet is not configured on the switch.

The following commands will enable the default QoS configuration:

switch(config)# system qos
switch(config-sys-qos)# service-policy type queuing input fcoe-default-in-policy
switch(config-sys-qos)# service-policy type queuing output fcoe-default-out-policy
switch(config-sys-qos)# service-policy type qos input fcoe-default-in-policy
switch(config-sys-qos)# service-policy type network-qos fcoe-default-nq-policy

CHAPTER 2

Modular QoS CLI

The Cisco Modular QoS CLI (MQC) provides a standard set of commands for configuring QoS.

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Modular QoS CLI

Overview

You can use MQC to define additional traffic classes and to configure QoS policies for the whole system and
for individual interfaces. Configuring a QoS policy with MQC consists of the following steps:

1

Define traffic classes.

2

Associate policies and actions with each traffic class.

3

Attach policies to logical or physical interfaces as well as at the global system level.

MQC provides two command types to define traffic classes and policies:

class-map

Defines a class map that represents a class of traffic based on packet-matching criteria. Class maps are
referenced in policy maps.

The class map classifies incoming packets based on matching criteria, such as the IEEE 802.1p class
of service (CoS) value. Unicast and multicast packets are classified.

policy-map

Defines a policy map that represents a set of policies to be applied on a class-by-class basis to class
maps.

The policy map defines a set of actions to take on the associated traffic class, such as limiting the
bandwidth or dropping packets.

Note

You define the following class-map and policy-map object types when you create them:

network-qos

Defines MQC objects that you can use for system level related actions.

qos

Defines MQC objects that you can use for classification.

queuing

Defines MQC objects that you can use for queuing and scheduling.

The qos type is the default for the class-map and policy-map commands, but not for the service-policy
which requires that you specify an explicit type.

You can attach policies to interfaces or EtherChannels as well as at the global system level by using the
service-policy command.

You can view all or individual values for MQC objects by using the show class-map and show policy-map
commands.

An MQC target is an entity (such as an Ethernet interface) that represents a flow of packets. A service policy
associates a policy map with an MQC target and specifies whether to apply the policy on incoming or outgoing
packets. This mapping enables the configuration of QoS policies such as marking, bandwidth allocation,
buffer allocation, and so on.

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Overview

QoS for Traffic Directed to the CPU

The device automatically applies QoS policies to traffic that is directed to the CPU to ensure that the CPU is
not flooded with packets. Control traffic, such as bridge protocol data units (BPDU) frames, is given higher
priority to ensure delivery.

QoS for Traffic Directed to the CPU

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QoS for Traffic Directed to the CPU

Overview

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Configuring Classification

This chapter contains the following sections:

Information About Classification, page 7

•

Ingress Classification Policies, page 8

•

Licensing Requirements for Classification, page 8

•

Configuring Classification, page 8

•

Verifying the Classification Configuration, page 16

•

Information About Classification

Classification is the separation of packets into traffic classes. You configure the device to take a specific action
on the specified classified traffic, such as policing or marking down, or other actions.

You can create class maps to represent each traffic class by matching packet characteristics with classification
criteria.

CHAPTER 3

Table 1: Classification Criteria

DescriptionClassification Criteria

Criteria specified in a named class-map object.Class map

Precedence

Differentiated Services Code Point (DSCP)

Protocol

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Precedence value within the Type of Service (ToS)
byte of the IP Header.

DSCP value within the DIffServ field of the IP
Header.

Selected set of protocols, including Address
Resolution Protocol (ARP) and Connectionless
Network Service (CLNS).

Ingress Classification Policies

Configuring Classification

DescriptionClassification Criteria

IP RTP

ACL

Table 2: Supported RFCs

RFC 2474

Ingress Classification Policies

You use classification to partition traffic into classes. You classify the traffic based on the packet property
(CoS field) or the packet header fields that include IP precedence, Differentiated Services Code Point (DSCP),
and Layer 2 to Layer 4 parameters. The values used to classify traffic are called match criteria.

Traffic that fails to match any class is assigned to a default class of traffic called class-default.

Identify applications using Real-time Transport
Protocol (RTP) by UDP port number range.

Traffic is classified by the criteria defined in the
access control list (ACL).

TitleRFC

Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers

Licensing Requirements for Classification

This feature does not require a 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.

Configuring Classification

Configuring Class Maps

You can create or modify a class map with the class-map command. The class map is a named object that
represents a class of traffic. In the class map, you specify a set of match criteria for classifying the packets.
You can then reference class maps in policy maps.

The class map type default is type qos and its match criteria default is match-all.Note

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Configuring Classification

Configuring CoS Classification

Procedure

PurposeCommand or Action

Step 1

Step 2

Step 3

switch(config)# class-map
[type {network-qos | qos |
queuing}] class-map name

switch(config)# class-map
[type qos] [match-all |
match-any] class-map name

Enters global configuration mode.switch# configure terminal

Creates or accesses a named object that represents the specified class
of traffic.

Class-map names can contain alphabetic, hyphen, or underscore
characters, are case sensitive, and can be up to 40 characters.

The three class-map configuration modes are as follows:

• network-qos—Network-wide (global) mode. CLI prompt:

switch(config-cmap-nq)#

• qos—Classification mode; this is the default mode. CLI

prompt: switch(config-cmap-qos)#

• queuing—Queuing mode. CLI prompt:

switch(config-cmap-que)#

(Optional)
Specifies that packets must match any or all criteria that is defined
for a class map.

• match-all—Classifies traffic if packets match all criteria that

is defined for a specified class map (for example, if both the
defined CoS and the ACL criteria match).

• match-any—Classifies traffic if packets match any criteria

that is defined for a specified class map (for example, if either
the CoS or the ACL criteria matches).

Class-map names can contain alphabetic, hyphen, or underscore
characters, are case sensitive, and can be up to 40 characters.

Step 4

switch(config)# no class-map
[type {network-qos | qos |
queuing}] class-name

(Optional)
Deletes the specified class map.

Note

You cannot delete the two system-defined class maps:

class-fcoe and class-default.
Class-map names can contain alphabetic, hyphen, or underscore
characters, are case sensitive, and can be up to 40 characters.

Configuring CoS Classification

You can classify traffic based on the class of service (CoS) in the IEEE 802.1Q header. This 3-bit field is
defined in IEEE 802.1p to support QoS traffic classes. CoS is encoded in the high order 3 bits of the VLAN
ID Tag field and is referred to as user_priority.

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Configuring Precedence Classification

The Cisco Nexus 2148 Fabric Extender does not support frames with the dot1p vlan 0 tag.Note

If a system class is configured with a no-drop function, the match cos command serves an additional purpose.
The switch sends the CoS value to the adapter so that the adapter will apply a PFC pause for this CoS value.

The FCoE system class has a default CoS value of 3. You can add a match cos configuration to the FCoE
system class to set a different CoS value. A PFC pause will be applied to traffic that matches the new value.

Procedure

Configuring Classification

PurposeCommand or Action

Step 1

Step 2

switch(config)# class-map type
qos class-name

Enters global configuration mode.switch# configure terminal

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

Step 3

switch(config-cmap-qos)# match
cos cos-value

Specifies the CoS value to match for classifying packets into
this class. You can configure a CoS value in the range of 0
to 7.

Note

When a Cisco Nexus 2148T Fabric Extender is
connected and in use, data traffic should never be
marked with a CoS value of 7. CoS 7 is reserved for
control traffic transiting the Fabric Extender.

Step 4

switch(config-cmap-qos)# no
match cos cos-value

(Optional)
Removes the match from the traffic class.

This example shows how to classify traffic by matching packets based on a defined CoS value:

switch# configure terminal
switch(config)# class-map type qos match-any class_cos
switch(config-cmap-qos)# match cos 4, 5-6

Use the show class-map command to display the CoS value class-map configuration:

switch# show class-map class_cos

Configuring Precedence Classification

You can classify traffic based on the precedence value in the type of service (ToS) byte field of the IP header
(either IPv4 or IPv6). The following table shows the precedence values:

Table 3: Precedence Values

List of Precedence ValuesValue

IP precedence value<0-7>

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Configuring Classification

Configuring Precedence Classification

List of Precedence ValuesValue

Critical precedence (5)critical

Flash precedence (3)flash

Flash override precedence (4)flash-override

Immediate precedence (2)immediate

internet

Procedure

Step 1

Step 2

Step 3

switch(config)# class-map type qos
match-any class-name

switch(config-cmap-qos)#match
precedence precedence-values

Internetwork control precedence
(6)

Network control precedence (7)network

Priority precedence (1)priority

Routine precedence (0)routine

PurposeCommand or Action

Enters global configuration mode.switch# configure terminal

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

Configures the traffic class by matching packets based
on precedence values. For a list of precedence values,
see the Precedence Values table.

Step 4

switch((config-cmap-qos)# no match
precedence precedence-values

(Optional)
Removes the match from the traffic class. For a list of
precedence values, see the Precedence Values table.

This example shows how to classify traffic by matching packets based on the precedence value in the ToS
byte field of the IP header:

switch# configure terminal
switch(config)# class-map type qos match-any class_precedence
switch(config-cmap-qos)# match precedence 1-2, critical

Use the show class-map command to display the IP precedence value class-map configuration:

switch# show class-map class_precedence

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Configuring DSCP Classification

Configuring DSCP Classification

You can classify traffic based on the Differentiated Services Code Point (DSCP) value in the DiffServ field
of the IP header (either IPv4 or IPv6).

Table 4: Standard DSCP Values

Configuring Classification

List of DSCP ValuesValue

af11

af12

af13

af21

af22

af23

af31

af32

af33

af41

af42

af43

AF11 dscp (001010)—decimal value 10

AF12 dscp (001100)—decimal value 12

AF13 dscp (001110)—decimal value 14

AF21 dscp (010010)—decimal value 18

AF22 dscp (010100)—decimal value 20

AF23 dscp (010110)—decimal value 22

AF31 dscp (011010)—decimal value 26

AF32 dscp (011100)—decimal value 28

AF33 dscp (011110)—decimal value 30

AF41 dscp (100010)—decimal value 34

AF42 dscp (100100)—decimal value 36

AF43 dscp (100110)—decimal value 38

cs1

CS1 (precedence 1) dscp (001000)—decimal value
8

cs2

CS2 (precedence 2) dscp (010000)—decimal value
16

cs3

CS3 (precedence 3) dscp (011000)—decimal value
24

cs4

CS4 (precedence 4) dscp (100000)—decimal value
32

cs5

CS5 (precedence 5) dscp (101000)—decimal value
40

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Configuring Classification

Configuring Protocol Classification

List of DSCP ValuesValue

cs6

cs7

default

ef

Procedure

Step 1

Step 2

Step 3

switch(config)# class-map type qos

class-name

switch(config-cmap-qos)# match
dscp dscp-list

CS6 (precedence 6) dscp (110000)—decimal value
48

CS7 (precedence 7) dscp (111000)—decimal value
56

Default dscp (000000)—decimal value 0

EF dscp (101110)—decimal value 46

PurposeCommand or Action

Enters global configuration mode.switch# configure terminal

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

Configures the traffic class by matching packets based on
the values in the dscp-list variable. For a list of DSCP
values, see the Standard DSCP Values table.

Step 4

switch(config-cmap-qos)# no match
dscp dscp-list

This example shows how to classify traffic by matching packets based on the DSCP value in the DiffServ
field of the IP header:

switch# configure terminal
switch(config)# class-map type qos match-any class_dscp
switch(config-cmap-qos)# match dscp af21, af32

Use the show class-map command to display the DSCP class-map configuration:

switch# show class-map class_dscp

Configuring Protocol Classification

You can classify traffic based on the IPv4 Protocol field or the IPv6 Next Header field in the IP header. The
following table shows the protocol arguments:

(Optional)
Removes the match from the traffic class. For a list of
DSCP values, see the Standard DSCP Values table.

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Configuring IP RTP Classification

Table 5: Protocol Arguments

Configuring Classification

DescriptionArgument

Address Resolution Protocol (ARP)arp

CLNS End Systemsclns_es

CLNS Intermediate Systemclns_is

Dynamic Host Configuration (DHCP)dhcp

Label Distribution Protocol (LDP)ldp

NetBIOS Extended User Interface (NetBEUI)netbios

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# class-map type qos

class-name

Enters configuration mode.switch# configure terminal

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

Step 3

switch(config-cmap-qos)# match protocol
{arp | clns_es | clns_is | dhcp | ldp |

Configures the traffic class by matching packets
based on the specified protocol.

netbios}

Step 4

switch(config-cmap-qos)# no match
protocol {arp | clns_es | clns_is | dhcp | ldp

(Optional)
Removes the match from the traffic class.

| netbios}

This example shows how to classify traffic by matching packets based on the protocol field:

switch# configure terminal
switch(config)# class-map type qos class_protocol
switch(config-cmap-qos)# match protocol arp

Use the show class-map command to display the protocol class-map configuration:

switch# show class-map class_protocol

Configuring IP RTP Classification

The IP Real-time Transport Protocol (RTP) is a transport protocol for real-time applications that transmits
data such as audio or video and is defined by RFC 3550. Although RTP does not use a common TCP or UDP

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Configuring Classification

Configuring ACL Classification

port, you typically configure RTP to use ports 16384 to 32767. UDP communications use an even port and
the next higher odd port is used for RTP Control Protocol (RTCP) communications.

You can classify based on UDP port ranges, which are likely to target applications using RTP.

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# class-map type qos

class-name

Enters global configuration mode.switch# configure terminal

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

Step 3

switch(config-cmap-qos)# match ip
rtp port-number

Configures the traffic class by matching packets based
on a range of lower and upper UDP port numbers, which
is likely to target applications using RTP. Values can
range from 2000 to 65535.

Step 4

switch(config-cmap-qos)# no match
ip rtp port-number

(Optional)
Removes the match from the traffic class.

The following example shows how to classify traffic by matching packets based on UDP port ranges that are
typically used by RTP applications:

switch# configure terminal
switch(config)# class-map type qos match-any class_rtp
switch(config-cmap-qos)# match ip rtp 2000-2100, 4000-4100

Use the show class-map command to display the RTP class-map configuration:

switch# show class-map class_rtp

Configuring ACL Classification

You can classify traffic by matching packets based on an existing access control list (ACL). Traffic is classified
by the criteria defined in the ACL. The permit and deny ACL keywords are ignored in the matching; even
if a match criteria in the access-list has a deny action, it is still used for matching for this class.

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# class-map type qos

class-name

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Enters global configuration mode.switch# configure terminal

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

Verifying the Classification Configuration

Configuring Classification

PurposeCommand or Action

Step 3

switch(config-cmap-qos)# match
access-group name acl-name

Configures a traffic class by matching packets based on
the acl-name. The permit and deny ACL keywords are
ignored in the matching.

Note

You can only define a single ACL in a class map.

You cannot add any other match criteria to a class
with a match access-group defined.

Step 4

switch(config-cmap-qos)# no match
access-group name acl-name

(Optional)
Removes the match from the traffic class.

This example shows how to classify traffic by matching packets based on existing ACLs:

switch# configure terminal
switch(config)# class-map type qos class_acl
switch(config-cmap-qos)# match access-group name acl-01

Use the show class-map command to display the ACL class-map configuration:

switch# show class-map class_acl

Verifying the Classification Configuration

Use one of the following commands to verify the configuration:

show policy-map [name]

running-config ipqos

startup-config ipqos

PurposeCommand

Displays the class maps defined on the switch.show class-map

Displays the policy maps defined on the switch.
Optionally, you can display the named policy only.

Displays information about the running configuration
for QoS.

Displays information about the startup configuration
for QoS.

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Configuring Policy Maps

This chapter contains the following sections:

Information About Policy Types, page 17

•

Configuring Policy Maps, page 19

•

Verifying the Policy Map Configuration, page 24

•

Information About Policy Types

The device supports a number of policy types. You create class maps in the policy types.

There are three policy types

Network-qos

•

Queuing

•

CHAPTER 4

QoS

•

Before you enable FCoE on the Cisco Nexus device, you must enable class-fcoe in the three types of qos
policies (network QoS, queuing, and QoS) by entering the type qos policy maps command and applying at
least one FCoE QoS policy under system QoS.

The following QoS parameters can be specified for each type of class:

• Type network-qos—A network-qos policy is used to instantiate system classes and associate parameters

with those classes that are of system-wide scope.

◦ Classification—The traffic that matches this class are as follows:

◦ QoS Group—A class map of type network-qos identifies a system class and is matched by

its associated qos-group.

◦ Policy—The actions that are performed on the matching traffic are as follows:

A network-qos policy can only be attached to the system QoS target.Note

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Information About Policy Types

• Type queuing—A type queuing policy is used to define the scheduling characteristics of the queues

associated with system classes.

Configuring Policy Maps

◦ MTU—The MTU that needs to be enforced for the traffic that is mapped to a system class.

Each system class has a default MTU and the system class MTU is configurable.

◦ Multicast optimization—This configuration specifies if the performance of multicast traffic

mapped to this class will be optimized.

◦ Pause no-drop—No drop specifies lossless service for the system class. Drop specifies that

tail drop is used (arriving packets are dropped when the queue reaches its allocated size)
when a queue for this system class is full.

An additional parameter pfc-cos can be configured. This parameter identifies the class of
service (CoS) values to assert priority flow control (PFC) when traffic for a no-drop system
class is not mapped based purely on CoS experiences congestion.

You can change the buffer for the no-drop class.

◦

◦ Queue Limit—This configuration specifies the number of buffers that need to be reserved to

the queues of this system class. This option is not configurable for no-drop system classes.

Note

Some configuration parameters when applied to an EtherChannel are not reflected on
the configuration of the member ports.

◦ Classification—The traffic that matches this class are as follows:

◦ QoS Group—A class map of type queuing identifies a system class and is matched by its

associated QoS group.

◦ Policy—The actions that are performed on the matching traffic are as follows:

Note

These policies can be attached to the system qos target or to any interface. The output
queuing policy is used to configure output queues on the device associated with system
classes. The input queuing policy is used to configure scheduling for queues in the CNA.
The input queuing policy parameters are signaled to the CNA over the DCBX protocol.

◦ Bandwidth—Sets the guaranteed scheduling deficit weighted round robin (DWRR) percentage

for the system class.

◦ Priority—Sets a system class for strict-priority scheduling. Only one system class can be

configured for priority in a given queuing policy.

• Type qos—A type QoS policy is used to classify traffic that is based on various Layer 2, Layer 3, and

Layer 4 fields in the frame and to map it to system classes.

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Configuring Policy Maps

Configuring Policy Maps

Note

Some configuration parameters when applied to an EtherChannel are not reflected on
the configuration of the member ports.

◦ Classification—The traffic that matches this class are as follows:

◦ Access Control Lists—Classifies traffic based on the criteria in existing ACLs.

◦ Class of Service—Matches traffic based on the CoS field in the frame header.

◦ DSCP—Classifies traffic based on the Differentiated Services Code Point (DSCP) value in

the DiffServ field of the IP header.

◦ IP Real Time Protocol—Classifies traffic on the port numbers used by real-time applications.

◦ Precedence—Classifies traffic based on the precedence value in the type of service (ToS)

field of the IP header.

◦ Protocol—Classifies traffic based on the IPv4 Protocol field or the IPv6 Next Header field

of the IP header.

◦ Policy—The actions that are performed on the matching traffic are as follows:

Note

This policy can be attached to the system or to any interface. It applies to input traffic
only.

◦ QoS Group—Sets the QoS group that corresponds to the system class this traffic flow is

mapped to.

Configuring Policy Maps

Creating Policy Maps

The policy-map command is used to create a named object that represents a set of policies that are to be
applied to a set of traffic classes.

The device provides two default system classes: a no-drop class for lossless service (class-fcoe) and a drop
class for best-effort service (class-default). You can define up to four additional system classes for Ethernet
traffic.

The following predefined policy maps are used as default service policies:

network-qos: default-nq-policy

•

Input qos: default-in-policy

•

Input queuing: default-in-policy

•

Output queuing: default-out-policy

•

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Creating Policy Maps

Configuring Policy Maps

service-policy type qos input fcoe-default-in-policy

•

service-policy type queuing input fcoe-default-in-policy

•

service-policy type queuing output fcoe-default-out-policy

•

service-policy type network-qos fcoe-default-nq-policy

•

When class-fcoe is not included in the qos policies, vFC interfaces do not come up and increased drops occur.

You need to create a policy map to specify the policies for any user-defined class. In the policy map, you can
configure the QoS parameters for each class. You can use the same policy map to modify the configuration
of the default classes.

The device distributes all the policy-map configuration values to the attached network adapters.

Before You Begin

Before creating the policy map, define a class map for each new system class.

Procedure

Step 1

Step 2

Step 3

Step 4

switch(config)# policy-map [type
{network-qos | qos | queuing}]

policy-name

switch(config)# no policy-map
[type {network-qos | qos |
queuing}] policy-name

switch(config-pmap)# class [type
{network-qos | qos | queuing}]

class-name

PurposeCommand or Action

Enters global configuration mode.switch# configure terminal

Creates a named object representing a set of policies that are
to be 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.

The three policy-map configuration modes are as follows:

• network-qos—Network-wide (global) mode. CLI prompt:

switch(config-pmap-nq)#

• qos—Classification mode; this is the default mode. CLI

prompt: switch(config-pmap-qos)#

• queuing—Queuing mode. CLI prompt:

switch(config-pmap-que)#

(Optional)
Deletes the specified policy map.

Associates a class map with the policy map, and enters
configuration mode for the specified system class. The three
class-map configuration modes are as follows:

• network-qos—Network-wide (global) mode. CLI prompt:

switch(config-pmap-c-nq)#

• qos—Classification mode; this is the default mode. CLI

prompt: switch(config-pmap-c-qos)#

• queuing—Queuing mode. CLI prompt:

switch(config-pmap-c-que)#

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Configuring Policy Maps

PurposeCommand or Action

Note

Configuring Type QoS Policies

The associated class map must be the same type as
the policy-map type.

Step 5

switch(config-pmap)# no class
[type {network-qos | qos |
queuing}] class-name

Configuring Type QoS Policies

Type qos policies are used for classifying the traffic of a specific system class identified by a unique qos-group
value. A type qos policy can be attached to the system or to individual interfaces (including Fabric Extender
host interfaces) for ingress traffic only.

You can set a maximum of five QoS groups for ingress traffic.

Procedure

Step 1

Step 2

switch(config)# policy-map type
qos policy-name

(Optional)
Deletes the class map association.

PurposeCommand or Action

Enters global configuration mode.switch# configure terminal

Creates a named object that represents a set of policies that
are to be 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 3

Step 4

switch(config-pmap-qos)# [class |
class-default] type qos class-name

switch(config-pmap-c-qos)# set
qos-group qos-group-value

Associates a class map with the policy map, and enters
configuration mode for the specified system class.

Note

Configures one or more qos-group values to match on for
classification of traffic into this class map. The list below
identifies the ranges of the qos-group-value . There is no
default value.

This example shows how to define a type qos policy map:

switch# configure terminal
switch(config)# policy-map type qos policy-s1
switch(config-pmap-qos)# class type qos class-s1
switch(config-pmap-c-qos)# set qos-group 2

The associated class map must be the same type as
the policy map type.

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Configuring Type Network QoS Policies

Configuring Type Network QoS Policies

Type network qos policies can only be configured on the system qos attachment point. They are applied to
the entire switch for a particular class.

Procedure

Configuring Policy Maps

PurposeCommand or Action

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

switch(config)# policy-map type
network-qos policy-name

switch(config-pmap-nq)# class
type network-qos class-name

mtu-value

switch(config-pmap-c-nq)# no
mtu

no-drop

switch(config-pmap-c-nq)#

multicast-optimize

Enters global configuration mode.switch# configure terminal

Creates a named object that represents a set of policies that
are to be 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.

Associates a class map with the policy map, and enters
configuration mode for the specified system class.

Note

The associated class map must be the same type as
the policy map type.

Specifies the MTU value in bytes.switch(config-pmap-c-nq)# mtu

Note

The mtu-value that you configure must be less than
the value set by the system jumbomtu command.

(Optional)
Resets the MTU value in this class.

Configures a no-drop class.switch(config-pmap-c-nq)# pause

Enables multicast optimization. Multicast traffic in this class
will be served by all available multicast queues.

Note

Only one class in a policy map can be configured for
multicast optimization.

Note

For the Cisco Nexus device, multicast optimization
is enabled by default on class-default. You must
remove it from class-default before enabling it on a
user-defined class.

Step 8

Step 9

switch(config-pmap-c-nq)# no
multicast-optimize

switch(config-pmap-c)# pause
no-drop [pfc-cos pfc-cos-value]

(Optional)
Disables multicast optimization.

Configures a no-drop class. If you do not specify this
command, the default policy is drop.

Note

The operation for the drop policy is a simple tail drop,
where arriving packets will be dropped if the queue

increases to its allocated size.
The pfc-cos-value range is from 0 to 7. This option is supported
only for for a ACL-based system class (which filters traffic
using criteria other than cos-based matches).

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Configuring Policy Maps

PurposeCommand or Action

Caution

Configuring Type Queuing Policies

The list of CoS values can potentially include the
CoS value that is used for FCoE traffic in
class-fcoe. You must determine if this is desired
behavior for your topology.

Step 10

Step 11

switch(config-pmap-c-nq)# no
pause no-drop

switch(config-pmap-c-nq)#

queue-limit number-bytes bytes

(Optional)
Removes the no-drop option from this class.

Specifies the tail drop threshold on this interface. The threshold
range is from 20480 to 204800 bytes.

Note

The queue limit can only be configured on drop
classes. If you try to configure a queue limit on a
no-drop class, or try to configure no-drop on a class
where a queue limit is already defined, the CLI will

return an error.
Use the pause no-drop buffer size option to change the buffer
size and pause threshold for the no-drop class.

Step 12

Step 13

Step 14

switch(config-pmap-c-nq)# no
queue-limit number-bytes bytes

switch(config-pmap-c-nq)# set
cos cos-value

switch(config-pmap-c-nq)# no
set cos cos-value

(Optional)
Disables the queue limit specification in this class.

Specifies a 802.1Q CoS value which is used to mark packets
on this interface. The value range is from 0 to 7.

(Optional)
Disables the marking operation in this class.

This example shows how to define a type network-qos policy map:

switch# configure terminal
switch(config)# policy-map type network-qos policy-que1
switch(config-pmap-nq)# class type network-qos class-que1
switch(config-pmap-c-nq)# mtu 5000
switch(config-pmap-c-nq)# set cos 4

Configuring Type Queuing Policies

Type queuing policies are used for scheduling and buffering the traffic of a specific system class. A type
queuing policy is identified by its QoS group and can be attached to the system or to individual interfaces
(except for Fabric Extender host interfaces) for input or output traffic.

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# policy-map type
queuing policy-name

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Enters global configuration mode.switch# configure terminal

Creates a named object that represents a set of policies that
are to be applied to a set of traffic classes. Policy-map

Verifying the Policy Map Configuration

Configuring Policy Maps

PurposeCommand or Action

names can contain alphabetic, hyphen, or underscore
characters, are case sensitive, and can be up to 40
characters.

Step 3

Step 4

Step 5

Step 6

Step 7

switch(config-pmap-que)# class
type queuing class-name

switch(config-pmap-c-que)#

priority

switch(config-pmap-c-que)# no
priority

switch(config-pmap-c-que)#

bandwidth percent percentage

switch(config-pmap-c-que)# no
bandwidth percent percentage

Associates a class map with the policy map, and enters
configuration mode for the specified system class.

Specifies that traffic in this class is mapped to a strict
priority queue.

Note

(Optional)
Removes the strict priority queuing from the traffic in this
class.

Specifies the guaranteed percentage of interface bandwidth
allocated to this class. By default, no bandwidth is specified
for a class.

Note

(Optional)
Removes the bandwidth specification from this class.

Only one class in each policy map can have strict
priority set on it.

Before you can successfully allocate bandwidth
to the class, you must first reduce the default
bandwidth configuration on class-default and
class-fcoe.

Verifying the Policy Map Configuration

PurposeCommand

show policy-map [name]

show policy-map interface [interface number]

show policy-map system

show policy-map type {network-qos | qos |
queuing} [name]

running-config ipqos

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Displays the policy maps defined on the switch.
Optionally, you can display the named policy only.

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

Displays the policy map settings attached to the
system qos.

Displays the policy map settings for a specific policy
type. Optionally, you can display the named policy
only.

Displays information about the running configuration
for QoS.

Configuring Policy Maps

Verifying the Policy Map Configuration

PurposeCommand

startup-config ipqos

Displays information about the startup configuration
for QoS.

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Verifying the Policy Map Configuration

Configuring Policy Maps

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Configuring Marking

This chapter contains the following sections:

Information About Marking, page 27

•

Configuring Marking, page 27

•

Verifying the Marking Configuration, page 32

•

Information About Marking

Marking is a method that you use to modify the QoS fields of the incoming and outgoing packets.

You can use marking commands in traffic classes that are referenced in a policy map. The marking features
that you can configure are listed below:

DSCP

•

CHAPTER 5

IP precedence

•

CoS

•

Configuring Marking

Configuring DSCP Marking

For Cisco Nexus devices, you can set the DSCP value in the six most significant bits of the DiffServ field of
the IP header to a specified value. You can enter numeric values from 0 to 63, in addition to the standard
DSCP values shown in the table below:

Note

You can set DSCP or IP Precedence but you can not set both values because they modify the same field
in the IP packet.

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Configuring DSCP Marking

Table 6: Standard DSCP Values

Configuring Marking

List of DSCP ValuesValue

af11

af12

af13

af21

af22

af23

af31

af32

af33

af41

af42

af43

AF11 dscp (001010)—decimal value 10

AF12 dscp (001100)—decimal value 12

AF13 dscp (001110)—decimal value 14

AF21 dscp (010010)—decimal value 18

AF22 dscp (010100)—decimal value 20

AF23 dscp (010110)—decimal value 22

AF31 dscp (011010)—decimal value 26

AF40 dscp (011100)—decimal value 28

AF33 dscp (011110)—decimal value 30

AF41 dscp (100010)—decimal value 34

AF42 dscp (100100)—decimal value 36

AF43 dscp (100110)—decimal value 38

cs1

cs2

cs3

cs4

cs5

cs6

cs7

default

CS1 (precedence 1) dscp (001000)—decimal value
8

CS2 (precedence 2) dscp (010000)—decimal value
16

CS3 (precedence 3) dscp (011000)—decimal value
24

CS4 (precedence 4) dscp (100000)—decimal value
32

CS5 (precedence 5) dscp (101000)—decimal value
40

CS6 (precedence 6) dscp (110000)—decimal value
48

CS7 (precedence 7) dscp (111000)—decimal value
56

Default dscp (000000)—decimal value 0

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Configuring Marking

Configuring IP Precedence Marking

List of DSCP ValuesValue

ef

Procedure

Step 1

Step 2

Step 3

Step 4

Step 5

policy-map type qos

qos-policy-map-name

class [type qos]
{class-map-name |

class-default}

set dscp dscp-value

set qos-group y

EF dscp (101110)—decimal value 46

PurposeCommand or Action

Enters configuration mode.config t

Creates or accesses the policy map named policy-map-name,
and then enters policy-map mode. The policy-map name can
contain alphabetic, hyphen, or underscore characters, is case
sensitive, and can be up to 40 characters.

Creates a reference to class-map-name, and enters policy-map
class configuration mode. Use the class-default keyword to
select all traffic that is not currently matched by classes in the
policy map.

Sets the DSCP value to dscp-value. See the Standards DSCP
Values table.

Specifies the qos-group. The group value can be from 1 to 5.

Note

Traffic in the class-default system class (qos-group 0),
cannot be marked with DSCP.

This example shows how to set the DSCP value to 10 and specify the qos-group to 2.

policy-map type qos test-bulkdata

class type qos bulkdata

set dscp 10
set qos-group 2

Configuring IP Precedence Marking

You can set the value of the IP precedence field in bits 0 to 2 of the IPv4 type of service (ToS) field or the
equivalent Traffic Class field for IPv6 of the IP header. The following table shows the precedence values:

Note

You can set IP Precedence or DSCP but you can not set both values because they modify the same field
in the IP packet.

Table 7: Precedence Values

List of Precedence ValuesValue

IP precedence value<0-7>

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Configuring CoS Marking

Configuring Marking

List of Precedence ValuesValue

Critical precedence (5)critical

Flash precedence (3)flash

Flash override precedence (4)flash-override

Immediate precedence (2)immediate

Internetwork control precedence (6)internet

Network control precedence (7)network

Priority precedence (1)priority

Routine precedence (0)routine

Procedure

PurposeCommand or Action

Step 1

Step 2

policy-map [type qos]

qos-policy-map-name

Enters configuration mode.config t

Creates or accesses the policy map named policy-map-name,
and then enters policy-map mode. The policy-map name can
contain alphabetic, hyphen, or underscore characters, is case
sensitive, and can be up to 40 characters.

Step 3

class [type qos]
{class-map-name |
class-default}

Creates a reference to class-map-name, and enters policy-map
class configuration mode. Use the class-default keyword to
select all traffic that is not currently matched by classes in the
policy map.

Step 4

set precedence

precedence-value

switch(config)# policy-map type qos my_policy
switch(config-pmap-qos)# class type qos my_class
switch(config-pmap-c-qos)# set precedence 5
switch(config-pmap-c-qos)#

Sets the IP precedence value to precedence-value. You can
enter one of the values shown in the Precedence Values table.

Configuring CoS Marking

The value of the CoS field is recorded in the high-order three bits of the VLAN ID Tag field in the IEEE

802.1Q header.

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Configuring Marking

Required CoS Marking Configuration in a Layer 3 Topology

Procedure

PurposeCommand or Action

Step 1

Step 2

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

Enters global configuration mode.switch# configure terminal

Creates or accesses the policy map named policy-map-name
and enters policy-map mode.

The policy-map name can contain alphabetic, hyphen, or
underscore characters, is case sensitive, and can be up to
40 characters.

Step 3

switch(config-pmap-nq) # class [type
network-qos] {class-map name

|class-default}

Creates a reference to the class-map-name and enters
policy-map class configuration mode.

Use the class-default keyword to select all traffic that is
not currently matched by classes in the policy map.

Step 4

cos-value

Specifies the CoS value to cos-value.switch(config-pmap-c-nq) # set cos

The cos-value can range from 0 to 7.

Note

This command is supported only for egress
policies.

Required CoS Marking Configuration in a Layer 3 Topology

In Layer 3 topologies, you must configure each QoS group in the network-qos policy with a unique cos value.

Procedure

Step 1

Step 2

Step 3

Step 4

switch(config) # policy-map
[type network-qos] policy-map

name

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

PurposeCommand or Action

Displays the already configured policy maps and CoS values.switch# show policy-map system

In Layer 3 topologies, each qosgroup must have a unique CoS
value. Use the show policy-map system command to view
CoS values that have been used and that are unavailable for
QoS groups.

Enters global configuration mode.switch# configure terminal

Creates or accesses the policy map named policy-map-name
and enters policy-map mode.

The policy-map name can contain alphabetic, hyphen, or
underscore characters, is case sensitive, and can be up to 40
characters.

Creates a reference to the class-map-name and enters
policy-map class configuration mode.

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Verifying the Marking Configuration

Configuring Marking

PurposeCommand or Action

Use the class-default keyword to select all traffic that is not
currently matched by classes in the policy map.

Step 5

cos cos-value

Specifies the CoS value.switch(config-pmap-nq-c) # set

The value can range from 0 to 7.

Note

You can use this command only in egress policies.

In Layer 3 topologies, each qos-group must have a
unique cos configuration.

This example shows how to set the CoS value to 4 in a Layer 3 topology:

switch# show policy-map system

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

policy-map type network-qos pn-01

class type network-qos cn-01 match qos-group 1

mtu 8500
pause no-drop
set cos 2

class type network-qos cn-02 match qos-group 2

set cos 4
mtu 9216

class type network-qos cn-03 match qos-group 3

mtu 8000
set cos 6

class type network-qos cn-04 match qos-group 4

mtu 8750
set cos 7

class type network-qos cn-ip-multicast match qos-group 5

set cos 5
mtu 7500

class type network-qos class-default match qos-group 0

mtu 1500
multicast-optimize
set cos 1

...
switch# configure terminal
switch(config)# policy-map type network-qos pn-01
switch(config-pmap-nq)# class type network-qos cn-05
switch(config-pmap-c-nq)# set cos 3

Verifying the Marking Configuration

Use one of the following commands to verify the configuration:

PurposeCommand

Displays the class maps defined on the switch.show class-map

show policy-map [name]

running-config ipqos

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Displays the policy maps defined on the switch.
Optionally, you can display the named policy only.

Displays information about the running configuration
for QoS.

Configuring Marking

Verifying the Marking Configuration

PurposeCommand

startup-config ipqos

Displays informationa bout the startup configuration
for QoS.

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Verifying the Marking Configuration

Configuring Marking

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Configuring QoS on the System

This chapter contains the following sections:

Information About System Classes, page 35

•

Configuring System QoS, page 37

•

Verifying the System QoS Configuration, page 41

•

Information About System Classes

System Classes

The system qos is a type of MQC target. You use a service policy to associate a policy map with the system
qos target. A system qos policy applies to all interfaces on the switch unless a specific interface has an
overriding service-policy configuration. The system qos policies are used to define system classes, the classes
of traffic across the entire switch, and their attributes. To ensure QoS consistency (and for ease of configuration),
the device distributes the system class parameter values to all its attached network adapters using the Data
Center Bridging Exchange (DCBX) protocol.

If service policies are configured at the interface level, the interface-level policy always takes precedence
over system class configuration or defaults.

On the Cisco Nexus device, a system class is uniquely identified by a qos-group value. A total of six system
classes are supported. Two of the six system classes are defaults and are always present on the device. Up to
four additional system classes can be created by the administrator.

CHAPTER 6

Default System Classes

The device provides the following system classes:

Drop system class

•

By default, the software classifies all unicast and multicast Ethernet traffic into the default drop system
class. This class is identified by qos-group 0.

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MTU

Configuring QoS on the System

This class is created automatically when the system starts up (the class is named class-default in the
CLI). You cannot delete this class and you cannot change the match criteria associated with the default
class.

Note

If congestion occurs when data traffic (class-default) and FCoE traffic (class-fcoe) is
flowing at the same time, then the queuing percentage configuration starts up.

The FCoE traffic is a no-drop class and does not get policed to the bandwidth assigned
as per the queuing class. FCoE traffic cannot be dropped as it expects a lossless medium.
When congestion occurs PFC frames are generated at FCoE ingress interfaces and
dropping only occurs on the data traffic, even if data traffic is below the assigned
bandwidth.

For optimizing the throughput you can spread the data traffic load for a longer duration.

FCoE system class (For the Cisco Nexus 5500 Series device)

•

For the Cisco Nexus 5500 Series device, the class-fcoe is not automatically created. Before you enable
FCoE on the Cisco Nexus 5500 Series device running Cisco NX-OS Release 5.0(2)N1(1), you must
enable class-fcoe in the three types of qos policies:

type qos policy maps

◦

type network-qos policy map (attached to system qos)

◦

type queuing policy map (class-fcoe must be configured with a non-zero bandwidth percentage

◦

for input queuing policy maps.

When class-fcoe is not included in the qos policies, vFC interfaces do not come up and increased
drops occur.

MTU

Note

The Cisco Nexus 5500 Series device supports five user-defined classes and one default
drop system class.

The Cisco Nexus device is a Layer 2 switch, and it does not support packet fragmentation. A maximum
transmission unit (MTU) configuration mismatch between ingress and egress interfaces may result in packets
being truncated.

When configuring MTU, follow these guidelines:

MTU is specified per system class. The system class allows a different MTU for each class of traffic

•

but they must be consistent on all ports across the entire switch. You cannot configure MTU on the
interfaces.

Fibre Channel and FCoE payload MTU is 2158 bytes across the switch. As a result, the rxbufsize for

•

Fibre Channel interfaces is fixed at 2158 bytes. If the Cisco Nexus device receives an rxbufsize from a
peer that is different than 2158 bytes, it will fail the exchange of link parameters (ELP) negotiation and
not bring the link up.

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Enter the system jumbomtu command to define the upper bound of any MTU in the system. The system

•

jumbo MTU has a default value of 9216 bytes. The minimum MTU is 2158 bytes and the maximum
MTU is 9216 bytes.

The system class MTU sets the MTU for all packets in the class. The system class MTU cannot be

•

configured larger than the global jumbo MTU.

The FCoE system class (for Fibre Channel and FCoE traffic) has a default MTU of 2158 bytes. This

•

value cannot be modified.

The switch sends the MTU configuration to network adapters that support DCBX.

•

MTU is not supported in Converged Enhanced Ethernet (CEE) mode for DCBX.Note

Configuring System QoS

Configuring System QoS

Attaching the System Service Policy

The service-policy command specifies the system class policy map as the service policy for the system.

Procedure

Step 1

Step 2

Step 3

switch(config-sys-qos)#

service-policy type

{network-qos | qos | queuing}
[input | output] policy-name

PurposeCommand or Action

Enters global configuration mode.switch# configure terminal

Enters system class configuration mode.switch(config)# system qos

Specifies the policy map to use as the service policy for the system.
There are three policy-map configuration modes:

• network-qos—Network-wide (system qos) mode.

• qos—Classification mode (system qos input or interface input

only).

• queuing—Queuing mode (input and output at system qos and

interface).

Note

There is no default policy-map configuration mode; you
must specify the type. The input keyword specifies that
this policy map should be applied to traffic received on an
interface. The output keyword specifies that this
policy-map should be applied to traffic transmitted from
an interface. You can only apply input to a qos policy;
you can apply both input and output to a queuing policy.

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Restoring the Default System Service Policies

Configuring QoS on the System

PurposeCommand or Action

Step 4

switch(config-sys-qos)#

service-policy type

{network-qos | qos | queuing}
[input | output] fcoe default

policy-name

(Optional)
Specifies the default FCoE policy map to use as the service policy
for the system. There are four pre-defined policy-maps for FCoE:

service-policy type qos input fcoe-default-in-policy

•

service-policy type queuing input fcoe-default-in-policy

•

service-policy type queuing output fcoe-default-out-policy

•

service-policy type network-qos fcoe-default-nq-policy

•

Note

Before enabling FCoE on a Cisco Nexus device, you must
attach the pre-defined FCoE policy maps to the type qos,
type network-qos, and type queuing policy maps.

This example shows how to set a no-drop Ethernet policy map as the system class:

switch(config)# class-map type network-qos ethCoS4
switch(config-cmap-nq)# match qos-group
switch(config-cmap-nq)# exit
switch(config)# policy-map type network-qos ethNoDrop
switch(config-pmap-nq)# class type network-qos ethCoS4
switch(config-pmap-c-nq)# pause no-drop
switch(config-pmap-c-nq)# exit
switch(config-pmap-nq)# exit
switch(config)# system qos
switch(config-sys-qos)# service-policy type network-qos ethNoDrop

Restoring the Default System Service Policies

If you have created and attached new policies to the system QoS configuration, enter the no form of the
command to reapply the default policies.

Procedure

Step 1

Step 2

Step 3

Step 4

Step 5

switch(config-sys-qos)# no service-policy type
qos input policy-map name

network-qos policy-map name

queuing output policy-map name

PurposeCommand or Action

Enters global configuration mode.switch# configure terminal

Enters system class configuration mode.switch(config)# system qos

Resets the classification mode policy map.
This policy-map configuration is for system
QoS input or interface input only:

Resets the network-wide policy map.switch(config-sys-qos)# no service-policy type

Resets the output queuing mode policy map.switch(config-sys-qos)# no service-policy type

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Configuring QoS on the System

Configuring the Queue Limit for a Specified Fabric Extender

PurposeCommand or Action

Step 6

Resets the input queuing mode policy map.switch(config-sys-qos)# no service-policy type

queuing input policy-map name

The following example shows how to reset the system QoS configuration:

switch# configure terminal
switch(config)# system qos
switch(config-sys-qos)# no service-policy type qos input my-in-policy
switch(config-sys-qos)# no service-policy type network-qos my-nq-policy
switch(config-sys-qos)# no service-policy type queuing output my-out-policy
switch(config-sys-qos)# no service-policy type queuing input my-in-policy

Configuring the Queue Limit for a Specified Fabric Extender

At the Fabric Extender configuration level, you can control the queue limit for a specified Fabric Extender
for egress direction (from the network to the host). You can use a lower queue limit value on the Fabric
Extender to prevent one blocked receiver from affecting traffic that is sent to other noncongested receivers
("head-of-line blocking"). A higher queue limit provides better burst absorption and less head-of-line blocking
protection. You can use the no form of this command to allow the Fabric Extender to use all available hardware
space.

Note

At the system level, you can set the queue limit for Fabric Extenders by using the fex queue-limit
command. However, configuring the queue limit for a specific Fabric Extender will override the queue
limit configuration set at the system level for that Fabric Extender.

You can specify the queue limit for the following Fabric Extenders:

Cisco Nexus 2148T Fabric Extender (48x1G 4x10G SFP+ Module)

•

Cisco Nexus 2224TP Fabric Extender (24x1G 2x10G SFP+ Module)

•

Cisco Nexus 2232P Fabric Extender (32x10G SFP+ 8x10G SFP+ Module)

•

Cisco Nexus 2248T Fabric Extender (48x1G 4x10G SFP+ Module)

•

Cisco Nexus N2248TP-E Fabric Extender (48x1G 4x10G Module)

•

Cisco Nexus N2348UPQ Fabric Extender (48x10G SFP+ 6x40G QSFP Module)

•

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# fex fex-id

Enters global configuration mode.switch# configure terminal

Specifies the Fabric Extender and enters the Fabric
Extender mode.

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Enabling the Jumbo MTU

Configuring QoS on the System

PurposeCommand or Action

Step 3

switch(config-fex)# hardware

fex_card_type queue-limit
queue-limit

This example shows how to restore the default queue limit on a Cisco Nexus 2248T Fabric Extender:

switch# configure terminal
switch(config-if)# fex 101
switch(config-fex)# hardware N2248T queue-limit 327680

This example shows how to remove the queue limit that is set by default on a Cisco Nexus 2248T Fabric
Extender:

switch# configure terminal
switch(config)# fex 101
switch(config-fex)# no hardware N2248T queue-limit 327680

Enabling the Jumbo MTU

You can enable the jumbo Maximum Transmission Unit (MTU) for the whole switch by setting the MTU to
its maximum size (9216 bytes) in the policy map for the default Ethernet system class (class-default).

When you configure jumbo MTU on a port-channel subinterface you must first enable MTU 9216 on the base
interface and then configure it again on the subinterface. If you enable the jumbo MTU on the subinterface
before you enable it on the base interface then the following error will be displayed on the console:

switch(config)# int po 502.4
switch(config-subif)# mtu 9216
ERROR: Incompatible MTU values

For Layer 3 routing on Cisco Nexus devices, you need to configure the MTU on the Layer 3 interfaces (SVIs
and physical interfaces with IP addresses) in addition to the global QoS configuration below.

To use FCoE on switch, add class-fcoe in the custom network-qos policy. If already using FCoE, make sure
to add the below lines in the config so that the FCoE does not go down on the switch after enabling the jumbo
qos policy.

switch# conf t
switch(config)# policy-map type network-qos jumbo
switch(config-pmap-nq)# class type network-qos class-fcoe
switch(config-pmap-nq-c)# end

This example shows how to change qos to enable the jumbo MTU:

switch# conf t
switch(config)# policy-map type network-qos jumbo
switch(config-pmap-nq)# class type network-qos class-default
switch(config-pmap-c-nq)# mtu 9216

Configures the queue limit for the specified Fabric
Extender. The queue limit is specified in bytes. The range
is from 81920 to 652800 for a Cisco Nexus 2148T Fabric
Extender and from 2560 to 652800 for all other supported
Fabric Extenders.

Note

The system jumbomtu command defines the maximum MTU size for the switch. However, jumbo MTU
is supported only for system classes that have MTU configured.

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Configuring QoS on the System

Verifying the Jumbo MTU

On the Cisco Nexus device, traffic is classified into one of eight QoS groups. The MTU is configured at the
QoS group level. By default, all Ethernet traffic is in QoS group 0. To verify the jumbo MTU for Ethernet
traffic, use the show queueing interface ethernet slot/chassis_number command and find "HW MTU" in
the command output to check the MTU for QoS group 0. The value should be 9216.

The show interface command always displays 1500 as the MTU. Because the Cisco Nexus device supports
different MTUs for different QoS groups, it is not possible to represent the MTU as one value on a per interface
level.

Verifying the Jumbo MTU

Note

For Layer 3 routing on the Cisco Nexus device, you must verify the MTU on the Layer 3 interfaces (SVIs
and physical interfaces with IP addresses) in addition to the global QoS MTU. You can verify the Layer
3 MTU by using the show interface vlan vlan_number or show interface slot/chassis_number.

This example shows how to display jumbo MTU information for Ethernet 1/19:

switch# show queuing interface ethernet1/19
Ethernet1/19 queuing information:

TX Queuing

qos-group sched-type oper-bandwidth

0 WRR 50
1 WRR 50

RX Queuing

qos-group 0
q-size: 243200, HW MTU: 9280 (9216 configured)
drop-type: drop, xon: 0, xoff: 1520
Statistics:

Pkts received over the port : 2119963420
Ucast pkts sent to the cross-bar : 2115648336
Mcast pkts sent to the cross-bar : 4315084
Ucast pkts received from the cross-bar : 2592447431
Pkts sent to the port : 2672878113
Pkts discarded on ingress : 0
Per-priority-pause status : Rx (Inactive), Tx (Inactive)

qos-group 1
q-size: 76800, HW MTU: 2240 (2158 configured)
drop-type: no-drop, xon: 128, xoff: 240
Statistics:

Pkts received over the port : 0
Ucast pkts sent to the cross-bar : 0
Mcast pkts sent to the cross-bar : 0
Ucast pkts received from the cross-bar : 0
Pkts sent to the port : 0
Pkts discarded on ingress : 0
Per-priority-pause status : Rx (Inactive), Tx (Inactive)

Total Multicast crossbar statistics:

Mcast pkts received from the cross-bar : 80430744

Verifying the System QoS Configuration

Use one of the following commands to verify the configuration:

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Verifying the System QoS Configuration

Configuring QoS on the System

PurposeCommand

show policy-map system

show policy-map [name]

running-config ipqos

startup-config ipqos

Displays the policy map settings attached to the
system QoS.

Displays the policy maps defined on the switch.
Optionally, you can display the named policy only.

Displays the class maps defined on the switch.show class-map

Displays information about the running configuration
for QoS.

Displays information a bout the startup configuration
for QoS.

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Configuring QoS on Interfaces

This chapter contains the following sections:

Information About Interface QoS, page 43

•

Configuring Interface QoS, page 45

•

Verifying the Interface QoS Configuration, page 47

•

Information About Interface QoS

Trust Boundaries

The trust boundary is enforced by the incoming interface as follows:

All Fibre Channel and virtual Fibre Channel interfaces are automatically classified into the FCoE system

•

class.

CHAPTER 7

By default, all Ethernet interfaces are trusted interfaces.The 802.1p CoS and DSCP are preserved unless

•

the marking is configured. There is no default CoS to queue and DSCP to queue mapping. You can
define and apply a policy to create these mappings. By default, without a user defined policy, all traffic
is assigned to the default queue.

Any packet that is not tagged with an 802.1p CoS value is classified into the default drop system class.

•

If the untagged packet is sent over a trunk, it is tagged with the default untagged CoS value, which is
zero.

You can override the default untagged CoS value for an Ethernet interface or port channel.

•

You can override the default untagged CoS value for an Ethernet interface or a port channel interface

•

using the untagged cos cos-value command.

After the system applies the untagged CoS value, QoS functions the same as for a packet that entered the
system tagged with the CoS value.

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Policy for Fibre Channel Interfaces

Policy for Fibre Channel Interfaces

The egress queues are not configurable for native Fibre Channel interfaces. Two queues are available as
follows:

A strict priority queue to serve high-priority control traffic.

•

A queue to serve all data traffic and low-priority control traffic.

•

QoS for Multicast Traffic

By default, all multicast Ethernet traffic is classified into the default drop system class. This traffic is serviced
by one multicast queue.

Optimized multicasting allows use of the unused multicast queues to achieve better throughput for multicast
frames. If optimized multicast is enabled for the default drop system class, the system will use all 128 queues
to service the multicast traffic. When optimized multicast is enabled for the default drop system class, all 128
queues are given equal priority.

If you define a new system class, a dedicated multicast queue is assigned to that class. This queue is removed
from the set of queues available for the optimized multicast class.

The system provides two predefined class maps for matching broadcast or multicast traffic. These class maps
are convenient for creating separate policy maps for unicast and multicast traffic.

The predefined class maps are as follows:

Configuring QoS on Interfaces

Note

class-all-flood

The class-all-flood class map matches all broadcast, multicast, and unknown unicast traffic (across all
CoS values). If you configure a policy map with the class-all-flood class map, the system automatically
uses all available multicast queues for this traffic.

class-ip-multicast

The class-ip-multicast class map matches all IP multicast traffic. Policy options configured in this class
map apply to traffic across all Ethernet CoS values. For example, if you enable optimized multicast for
this class, the IP multicast traffic for all CoS values is optimized.

If you configure either of these predefined class maps as a no-drop class, the priority flow control capability
is applied across all Ethernet CoS values. In this configuration, pause will be applied to unicast and
multicast traffic.

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Configuring Interface QoS

Configuring Untagged CoS

Any incoming packet not tagged with an 802.1p CoS value is assigned the default untagged CoS value of
zero (which maps to the default Ethernet drop system class). You can override the default untagged CoS value
for an Ethernet or EtherChannel interface.

You can configure flow control on a Layer 2 or Layer 3 interface. Use the no switchport command to configure
a Layer 3 interface

On a Cisco Nexus device, you can configure a type qos policy map and untagged CoS on the same interface.

Procedure

Configuring Interface QoS

PurposeCommand or Action

Step 1

Step 2

Step 3

The following example shows how to set the CoS value to 4 for untagged frames received on an interface:

switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# untagged cos 4

switch(config)# interface {ethernet
[chassis/]slot/port | port-channel
channel-number}

switch(config-if)# untagged cos cos-value

Configuring an Interface Service Policy

An input qos policy is a service policy applied to incoming traffic on an Ethernet interface for classification.
For type queuing, the output policy is applied to all outgoing traffic that matches the specified class. When
you configure an input queuing policy on an interface or EtherChannel, the switch sends the configuration
data to the adapter using the DCBX protocol.

Note

Type qos policies can be activated only on Cisco Nexus device interfaces and Cisco Nexus Fabric Extender
interfaces. Type qos policies on Fabric Extender fabric interfaces or Fabric Extender fabric EtherChannel
interfaces are ineffective, though the Cisco NX-OS CLI does not reject the configuration.

We recommend that you do not configure type qos policy-maps on Fabric Extender fabric interfaces or
Fabric Extender fabric EtherChannel interfaces to avoid wasting hardware resources.

Enters global configuration mode.switch# configure terminal

Enters the configuration mode for the specified
interface or port channel.

Configures the untagged CoS value. Values
can be from 1 to 7.

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Configuring a Service Policy for a Layer 3 Interface

Procedure

Configuring QoS on Interfaces

PurposeCommand or Action

Step 1

Step 2

Step 3

Step 4

{ethernet [chassis/]slot/port |
port-channel channel-number}

switch(config-if)# service-policy
[type {qos | queuing}] [input |

output]policy-name

input policy-name

Enters global configuration mode.switch# configure terminal

Enters the configuration mode for the specified interface.switch(config)# interface

Note

The service policy on a port channel applies to all
member interfaces.

Specifies the policy map to use as the service policy for the
system. There are two policy-map configuration modes:

• qos—Classification mode; this is the default mode.

• queuing—Queuing mode.

Note

The input keyword specifies that this policy map
should be applied to traffic received on an interface.
The output keyword specifies that this policy map
should be applied to traffic transmitted from an
interface. You can only apply input to a qos policy;
you can only apply both input and output to a
queuing policy.

Applies the policy map to the interface.switch(config-if)# service-policy

Note

There is a restriction that system type qos policy
cannot be the same as any the type qos policy applied
to an interface or EtherChannel.

This example shows how to apply a policy to an Ethernet interface:

switch# configure terminal
switch(config)# interface ethernet 1/1
switch(config-if)# service-policy type qos input policy1

Configuring a Service Policy for a Layer 3 Interface

You can configure a service policy for a Layer 3 interface.

Procedure

PurposeCommand or Action

Step 1

Step 2

ethernet slot/port

Step 3

Enters global configuration mode.switch# configure terminal

Enters the configuration mode for the specified interface.switch(config)# interface

Selects the Layer 3 interface.switch(config-if)# no switchport

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Verifying the Interface QoS Configuration

PurposeCommand or Action

Step 4

switch(config-if)# service-policy
[type {qos | queuing} [input |
output]policy-name

Specifies the policy map to use as the service policy for the
Layer 3 interface. There are two policy-map configuration
modes:

• qos—Classification mode (this is the default mode).

• queuing—Queuing mode.

Note

The input keyword specifies that this policy map
should be applied to traffic received on an interface.
The output keyword specifies that this policy map
should be applied to traffic transmitted from an
interface. You can only apply input to a qos policy;
you can apply both input and output to a queuing
policy.

The following example shows how to attach a queuing policy map to a Layer 3 interface:

switch# configure terminal
switch(config)# interface ethernet 1/5
switch(config-if)# no switchport
switch(config-if)# service-policy type queuing output my_output_q_policy
switch(config-if)#

The following example shows how to attach an input qos policy map to a Layer 3 interface:

switch# configure terminal
switch(config)# interface ethernet 1/5
switch(config-if)# no switchport
switch(config-if)# service-policy type qos input my_input_qos_policy
switch(config-if)#

Verifying the Interface QoS Configuration

Use one of the following commands to verify the configuration:

PurposeCommand

Displays the class maps defined on the switch.show class-map

show policy-map [name]

show policy-map interface [interface number]

show queuing interface [interface slot/\port]

show interface flowcontrol [module numbef ]

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Displays the policy maps defined on the switch.
Optionally, you can display the named policy only.

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

Displays the queue configuration and statistics.

Displays the detailed listing of the flow control
settings on all interfaces.

Verifying the Interface QoS Configuration

Configuring QoS on Interfaces

PurposeCommand

show interface [interface slot/port]
priority-flow-control [module number]

show interface untagged-cos [module number]

running-config ipqos

startup-config ipqos

Displays the priority flow control details for a
specified interface.

Displays the untagged CoS values for all interfaces.

Displays information about the running configuration
for QoS.

Displays information about the startup configuration
for QoS.

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Configuring QoS on VLANs

This chapter contains the following sections:

Information About VLAN QoS, page 49

•

Precedence of QoS Policies, page 49

•

Limiting TCAM Entries for VLAN QoS, page 52

•

Guidelines and Limitations for VLAN QoS, page 52

•

Configuring VLAN QoS, page 53

•

Verifying the VLAN QoS Configuration, page 56

•

Feature History for VLAN QoS, page 56

•

Information About VLAN QoS

CHAPTER 8

On Cisco Nexus devices, you can configure quality of service (QoS) policies for classification and marking
on VLANs. The policies that you apply to a VLAN are applied to the traffic on the VLAN's Layer 2 and
switch virtual interface (SVI) ports.

Precedence of QoS Policies

The marking requirements in a QoS policy determine its precedence. Interface QoS policies take the highest
precedence, the VLAN QoS policies are next, and the System QoS policies have the lowest precedence.

However, if a VLAN is assigned both a VLAN QoS policy and a VLAN ACL (VACL), the VACL takes the
highest precedence.

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Example of Interface, System, and VLAN Policy Precedence

Example of Interface, System, and VLAN Policy Precedence

This example shows a configuration where the traffic on interface 1/1 with CoS 5 goes to qos-group 3. Traffic
on the other interfaces with VLAN 10 and CoS 5 go to qos-group 4. Traffic on interfaces other than VLAN
10 and CoS 5 go to qos-group 5.

class-map type qos match-all cm1

match cos 5

policy-map type qos pm-ifc

class cm1

set qos-group 3

class class-default

policy-map type qos pm-vlan

class cm1

set qos-group 4

class class-default

policy-map type qos pm-sys

class cm1

set qos-group 5

class class-default

system qos

service-policy type qos input pm-sys

vlan configuration 10

service-policy type qos input pm-vlan

interface Ethernet1/1

service-policy type qos input pm-ifc

Configuring QoS on VLANs

Example of Interface and System QoS Policy Precedence

This example shows a configuration where the traffic on interface 1/1 with CoS 5 goes to qos-group 3. Traffic
on the other interfaces with CoS 5 go to qos-group 5.

class-map type qos match-all cm1

match cos 5

policy-map type qos pm-ifc

class cm1

set qos-group 3

class class-default

policy-map type qos pm-sys

class cm1

set qos-group 5

class class-default

system qos

service-policy type qos input pm-sys

interface Ethernet1/1

service-policy type qos input pm-ifc

Example of System and VLAN Policy Precedence

This example shows a configuration where the traffic on VLAN 10 with CoS 5 goes to qos-group 4. Traffic
on the other VLANs with CoS 5 go to qos-group 5.

class-map type qos match-all cm1

match cos 5

policy-map type qos pm-vlan

class cm1

set qos-group 4

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Configuring QoS on VLANs

Example of VLAN QoS and VACL Policy Precedence

class class-default

policy-map type qos pm-sys

class cm1

set qos-group 5

class class-default

system qos

service-policy type qos input pm-sys

vlan configuration 10

service-policy type qos input pm-vlan

Example of VLAN QoS and VACL Policy Precedence

In this example, the packets with source IP address 10.10.10.1 are dropped. However, the other packets with
VLAN 10 and CoS 5 go to qos-group 4.

ip access-list al1

10 permit ip 10.10.10.1/24 any

vlan access-map v-am1

match ip address al1
action drop

vlan filter v-am1 vlan-list 10

class-map type qos match-all cm1

match cos 5

policy-map type qos pm-vlan

class cm1

set qos-group 4

class class-default

vlan configuration 10

service-policy type qos input pm-vlan

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Limiting TCAM Entries for VLAN QoS

Limiting TCAM Entries for VLAN QoS

The QoS TCAM region is shared by the interface QoS, system QoS, and VLAN QoS policies. You need to
limit the number of TCAM entries for the interface QoS policies in order to define VLAN QoS policies. Use
the hardware profile tcam feature interface-qos limit tcam-size to configure this limit.

Figure 1: QoS TCAM Region

Configuring QoS on VLANs

Guidelines and Limitations for VLAN QoS

A VLAN must have at least one active member port for a service policy to be configured on. If a VLAN

•

does not have at least one active member, and you configure a service policy on it, the configuration is
accepted; however, the TCAM is not programmed.

If a VLAN is removed with the no vlan number command, the service policy that is configured on that

•

VLAN is still present, but it is not active.

The TCAM must have enough free entries to configure the service policy on the VLAN.

•

A rollback might fail if the interface QoS limit is different in the running configuration than in the

•

rollback configuration.

If a VLAN with a QoS policy is configured on an interface with no QoS policy, the show policy-map

•

interface number command does not display the QoS policy configured on the VLAN.

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Configuring QoS on VLANs

Remove all interface QoS policies before changing the interface QoS limit.

•

Acllogs can only support logging levels of 3 or later.

•

We support only logging denials on the ACL, permits will not be logged.

•

Only one log message will be displayed until the flow stops and the rest is displayed later.

•

Configuring VLAN QoS

Configuring or Changing the Interface QoS TCAM Limit

To configure the interface_qos_limit to a specific number, the QoS region of the TCAMs in all of the ASICs
cannot have any interfaces policies configured beyond the offset of that number. For example, to configure
the interface_qos_limit to 1000, the QoS regions of the TCAMs in all of the ASICs cannot have any interface
policies configured beyond offset 1000.

Configuring VLAN QoS

Procedure

PurposeCommand or Action

Step 1

Step 2

Step 3

switch(config)# hardware profile tcam
feature interface-qos limit tcam-size

Enters global configuration mode.switch# configure terminal

Configures the interface QoS TCAM limit. The
tcam-size range is from 7 to 446 entries.

Displays the limits of the QoS TCAMs.switch(config)# show hardware profile

tcam feature qos

Step 4

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

(Optional)
Saves the change persistently through reboots and
restarts by copying the running configuration to
the startup configuration.

This example shows how to set the interface QoS TCAM limit to 20 entries:

switch(config)# configure terminal
switch(config)# hardware profile tcam feature interface-qos limit 20
switch(config)# show hardware profile tcam feature qos
Feature Limit (number of tcam entries)

-----------------------------------------------------­interface-qos 20
vlan-qos + global-qos 428

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

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Removing the Interface QoS Limit from the TCAM

Removing the Interface QoS Limit from the TCAM

Before You Begin

Remove all VLAN QoS policies.

•

Procedure

Configuring QoS on VLANs

PurposeCommand or Action

Step 1

Step 2

Enters global configuration mode.switch# configure terminal

Displays the limits of the QoS TCAMs.switch(config)# show hardware profile

tcam feature qos

Step 3

Step 4

switch(config)# no hardware profile tcam
feature interface-qos limit tcam-size

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

Configures the interface QoS TCAM limit. The
tcam-size range is from 7 to 446 entries.

(Optional)
Saves the change persistently through reboots and
restarts by copying the running configuration to
the startup configuration.

This example shows how to remove the interface QoS TCAM limit:

switch(config)# configure terminal
switch(config)# show hardware profile tcam feature qos
Feature Limit (number of tcam entries)

-----------------------------------------------------­interface-qos 20
vlan-qos + global-qos 428

switch(config)# no hardware profile tcam feature interface-qos limit 20
switch(config)# copy running-config startup-config

Configuring a Service Policy on a VLAN

Before You Begin

You must configure the interface QoS limit.

•

You must configure a policy map.

•

The TCAM must have enough free entries to configure the service policy on the VLAN.

•

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Configuring QoS on VLANs

Removing a Service Policy from a VLAN

Procedure

PurposeCommand or Action

Step 1

Step 2

Step 3

switch(config)# vlan configuration

vlan-number

switch(config-vlan)# service-policy
type qos input policy-name

Enters global configuration mode.switch# configure terminal

Creates a VLAN and enters VLAN configuration mode.
The vlan-number range is from 1 to 4094.

Assigns a policy map to the VLAN. The policy-name
is the name assigned to the policy map. The name can
be a maximum of 40 alphanumeric characters.

Step 4

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

(Optional)
Saves the change persistently through reboots and
restarts by copying the running configuration to the
startup configuration.

This example shows how to create a service policy and assign it to VLAN 10:

switch# configure terminal
switch(config)# class-map type qos cm1
switch(config-cmap-qos)# match cos 5
switch(config-cmap-qos)# policy-map type qos pm-vlan
switch(config-pmap-qos)# class cm1
switch(config-pmap-c-qos)# set qos-group 4
switch(config-pmap-c-qos)# exit
switch(config-pmap-qos)# exit
switch(config)# vlan configuration 10
switch(config-vlan-config)# service-policy type qos input pm-vlan
switch(config-vlan-config)#

Removing a Service Policy from a VLAN

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# vlan configuration

vlan-number

Step 3

switch(config-vlan-config)#no
service-policy type qos input

policy-name

Step 4

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

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Enters global configuration mode.switch# configure terminal

Enters VLAN configuration mode for the specified
VLAN. The vlan-number range is from 1 to 4094.

Removes the policy from the VLAN. The policy-name
is the name assigned to the policy map. The name can
be a maximum of 40 alphanumeric characters.

(Optional)
Saves the changes persistently through reboots and
restarts by copying the running configuration to the
startup configuration.

Verifying the VLAN QoS Configuration

This example shows how to remove the pm-vlan policy map from VLAN 10:

swtich# configure terminal
switch(config)# vlan configuration 10
switch(config-vlan-config)# no service-policy type qos input pm-vlan
switch(config-vlan-config)# copy running-config startup-config

Verifying the VLAN QoS Configuration

Use one of the following commands to verify the configuration:

Configuring QoS on VLANs

PurposeCommand

show policy-map vlan vlan-number

show policy-map [name]

running-config ipqos

startup-config ipqos

Feature History for VLAN QoS

Table 8: Feature History for VLAN QoS

Displays the QoS policies configured on the specified
VLAN.

Displays the policy maps defined on the switch.
Optionally, you can display the named policy only.

Displays information about the running configuration
for QoS.

Displays information about the startup configuration
for QoS.

Feature InformationReleaseFeature Name

This feature was introduced.5.1(3)N2(1)VLAN QoS

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Configuring Queuing and Flow Control

This chapter contains the following sections:

Information About Queues, page 57

•

Information About Flow Control, page 60

•

Configuring Queuing, page 61

•

Configuring Flow Control, page 65

•

Verifying the Queue and Flow Control Configurations, page 67

•

Information About Queues

Ingress Queuing Policies

CHAPTER 9

You can associate an ingress policy map with an Ethernet interface to guarantee bandwidth for the specified
traffic class or to specify a priority queue.

The ingress policy is applied in the adapter to all outgoing traffic that matches the specified CoS value.

When you configure an ingress policy for an interface, the switch sends the configuration data to the adapter.
If the adapter does not support the DCBX protocol or the ingress policy type-length-value (TLV), the ingress
policy configuration is ignored.

Egress Queuing Policies

You can associate an egress policy map with an Ethernet interface to guarantee the bandwidth for the specified
traffic class or to configure the egress queues.

The bandwidth allocation limit applies to all traffic on the interface including any FCoE traffic.

Each Ethernet interface supports up to eight queues, one for each system class. The queues have the following
default configuration:

In addition to these queues, control traffic that is destined for the CPU uses strict priority queues. These

•

queues are not accessible for user configuration.

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Configuring Queuing and Flow Control

Buffering and Queue Limits on the Cisco Nexus 5000 Platform

FCoE traffic (traffic that maps to the FCoE system class) is assigned a queue. This queue uses weighted

•

round-robin (WRR) scheduling with 50 percent of the bandwidth.

Standard Ethernet traffic in the default drop system class is assigned a queue. This queue uses WRR

•

scheduling with 100 percent of the bandwidth.

If you add a system class, a queue is assigned to the class. You must reconfigure the bandwidth allocation on
all affected interfaces. Bandwidth is not dedicated automatically to user-defined system classes.

You can configure one strict priority queue. This queue is serviced before all other queues except the control
traffic queue (which carries control rather than data traffic).

Buffering and Queue Limits on the Cisco Nexus 5000 Platform

The following buffering limits exist for the Cisco Nexus 5000 Platform:

Maximum ingress port buffering: 320KB per port.

•

Maximum egress port buffering: 160KB per port.

•

The following default buffer allocations per port exist for the Cisco Nexus 5000 Platform:

Table 9: Cisco Nexus 5000 Platform Default Buffer Allocations Per Port

Ingress Buffer (KB)Traffic Class

76.8Class-fcoe

76.8User-defined no-drop class of service with an MTU

less than 2240

81.9User-defined no-drop class of service with an MTU

greater than 2240

20.48Tail drop class of service

Class-default

All of the remaining buffer (243.2KB with the default
QoS configuration)

The default buffer allocation varies depending on the type of class. For example, if you create a regular tail
drop traffic class the default allocation is 20.48KB, unless you specify a larger size using the queue-limit
command.

To increase the buffer space available to a user-created qos-group, from a network-qos policy-map, use the
queue-limit command.

All of the available buffer is allocated to the class-default. When you define a new qos-group, the required
buffer for the new qos-group is taken from the class-default buffer.

Note

Each new class requires an additional 18.880KB, so the exact amount of buffer that is left in the class
default is 243.2KB minus the buffer used by other qos-groups minus 18.880KB times the number of
qos-groups.

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Configuring Queuing and Flow Control

Buffering and Queue Limits on the Cisco Nexus Device

The default QoS configuration for the Nexus 5000 platform creates the class-fcoe and class-default.

The show queuing interface command displays the configured qos-group and the ingress buffer allocated for
each qos-group.

Buffering and Queue Limits on the Cisco Nexus Device

On the Nexus 5500 platform, the packet buffer per port is 640KB. The Nexus 5548P, Nexus 5548UP, and the
Nexus 5596UP switch share the same buffer architecture. The Nexus 5500 platform implements Virtual Output
Queueing (VOQ) and ingress buffer architecture with the majority of the buffer allocated at ingress. The
architecture allows the switch to store packets at multiple ingress ports when there are multiple ports sending
traffic to one egress port which causes congestion.

The following default buffer allocations per port exist for the Cisco Nexus 5500 Platform:

Table 10: Cisco Nexus 5500 Platform Default Buffer Allocations Per Port

Ingress Buffer (KB)Traffic Class

79.360Class-fcoe

79.360User-defined no-drop with an MTU less than 2240

90.204User-defined no-drop class with an MTU greater than

2240

22.720Tail drop traffic class

Class-default

All of the remaining buffer (470 with default QoS
configuration)

The default buffer allocation varies depending on the type of class. For example, if you create a regular tail
drop traffic class the default allocation is 22.7KB, unless you specify a larger size using the queue-limit
command.

To increase the ingress buffer space available to a user-created qos-group, from a network-qos policy-map,
use the queue-limit command.

In addition to ingress buffer allocated for each user-created qos-group there is an additional 29.76KB buffer
required at egress for each qos-group.

With the default QoS configuration, all of the available buffer (470KB) is allocated to the class-default. When
you create a new qos-group, the buffer required for the new qos-group will be taken away from class-default.
The amount of buffer that is left for class-default equals 470 minus the ingress buffer used by other qos-groups
minus 29.76KB and times the number of qos-groups.

Note

Each new class requires an additional 29.76KB, so the exact amount of buffer that is left in the class default
equals 478 minus the buffer used by other qos-groups minus 18.880KB times the number of qos-groups.

The default QoS policy for the Cisco Nexus device does not create class-fcoe and does not reserve buffer and
qos-group for FCoE traffic.

The show queuing interface command can display the amount of ingress buffer allocated for each qos-group

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Information About Flow Control

Information About Flow Control

Link-Level Flow Control

IEEE 802.3x link-level flow control allows a congested receiver to communicate a transmitter at the other
end of the link to pause its data transmission for a short period of time. The link-level flow control feature
applies to all the traffic on the link.

The transmit and receive directions are separately configurable. By default, link-level flow control is disabled
for both directions.

On the Cisco Nexus device, Ethernet interfaces do not automatically detect the link-level flow control capability.
You must configure the capability explicitly on the Ethernet interfaces.

On each Ethernet interface, the switch can enable either priority flow control or link-level flow control (but
not both).

Configuring Queuing and Flow Control

Priority Flow Control

Priority flow control (PFC) allows you to apply pause functionality to specific classes of traffic on a link
instead of all the traffic on the link. PFC applies pause functionality based on the IEEE 802.1p CoS value.
When the switch enables PFC, it communicates to the adapter which CoS values to apply the pause.

Ethernet interfaces use PFC to provide lossless service to no-drop system classes. PFC implements pause
frames on a per-class basis and uses the IEEE 802.1p CoS value to identify the classes that require lossless
service.

In the switch, each system class has an associated IEEE 802.1p CoS value that is assigned by default or
configured on the system class. If you enable PFC, the switch sends the no-drop CoS values to the adapter,
which then applies PFC to these CoS values.

The default CoS value for the FCoE system class is 3. This value is configurable.

By default, the switch negotiates to enable the PFC capability. If the negotiation succeeds, PFC is enabled
and link-level flow control remains disabled regardless of its configuration settings. If the PFC negotiation
fails, you can either force PFC to be enabled on the interface or you can enable IEEE 802.x link-level flow
control.

If you do not enable PFC on an interface, you can enable IEEE 802.3X link-level pause.

Ensure that pause no-drop is configured on a class map for link-level pause.Note

By default, link-level pause is disabled.

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Configuring Queuing

Configuring the Queue Limit for a Specified Fabric Extender

At the Fabric Extender configuration level, you can control the queue limit for a specified Fabric Extender
for egress direction (from the network to the host). You can use a lower queue limit value on the Fabric
Extender to prevent one blocked receiver from affecting traffic that is sent to other noncongested receivers
("head-of-line blocking"). A higher queue limit provides better burst absorption and less head-of-line blocking
protection. You can use the no form of this command to allow the Fabric Extender to use all available hardware
space.

Configuring Queuing

Note

At the system level, you can set the queue limit for Fabric Extenders by using the fex queue-limit
command. However, configuring the queue limit for a specific Fabric Extender will override the queue
limit configuration set at the system level for that Fabric Extender.

You can specify the queue limit for the following Fabric Extenders:

Cisco Nexus 2148T Fabric Extender (48x1G 4x10G SFP+ Module)

•

Cisco Nexus 2224TP Fabric Extender (24x1G 2x10G SFP+ Module)

•

Cisco Nexus 2232P Fabric Extender (32x10G SFP+ 8x10G SFP+ Module)

•

Cisco Nexus 2248T Fabric Extender (48x1G 4x10G SFP+ Module)

•

Cisco Nexus N2248TP-E Fabric Extender (48x1G 4x10G Module)

•

Cisco Nexus N2348UPQ Fabric Extender (48x10G SFP+ 6x40G QSFP Module)

•

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# fex fex-id

Enters global configuration mode.switch# configure terminal

Specifies the Fabric Extender and enters the Fabric
Extender mode.

Step 3

This example shows how to restore the default queue limit on a Cisco Nexus 2248T Fabric Extender:

switch# configure terminal
switch(config-if)# fex 101
switch(config-fex)# hardware N2248T queue-limit 327680

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switch(config-fex)# hardware

fex_card_type queue-limit
queue-limit

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Configures the queue limit for the specified Fabric
Extender. The queue limit is specified in bytes. The range
is from 81920 to 652800 for a Cisco Nexus 2148T Fabric
Extender and from 2560 to 652800 for all other supported
Fabric Extenders.

Configuring No-Drop Buffer Thresholds

This example shows how to remove the queue limit that is set by default on a Cisco Nexus 2248T Fabric
Extender:

switch# configure terminal
switch(config)# fex 101
switch(config-fex)# no hardware N2248T queue-limit 327680

Configuring No-Drop Buffer Thresholds

You can configure the no-drop buffer threshold settings for 3000m lossless Ethernet.

Configuring Queuing and Flow Control

Note

To achieve lossless Ethernet for both directions, the devices connected to the Cisco Nexus device must
have the similar capability. The default buffer and threshold value for the no-drop can ensure lossless
Ethernet for up to 300 meters.

Procedure

PurposeCommand or Action

Step 1

Step 2

Step 3

Step 4

switch(config)# policy-map type
network-qos policy-map name

switch(config-pmap-nq)# class
type network-qos class-map name

switch(config-pmap-nq-c)# pause
no-drop buffer-size buffer-size
pause-threshold xoff-size
resume-threshold xon-size

Enters global configuration mode.switch# configure terminal

Enters policy-map network-qos class mode and identifies the
policy map assigned to the type network-qos policy map.

References an existing network QoS class map in a policy map
and enters class mode.

Specifies the buffer threshold settings for pause and resume
for 3000m lossless Ethernet:

• buffer-size—Buffer size for ingress traffic, in bytes. Valid

values are from 10240 to 490880.

Note

On a Cisco Nexus 5020 switch, you can
configure a maximum buffer size of 143680
bytes.

On a Cisco Nexus 5500 Series device, you can
configure a maximum buffer size of 152000
bytes.

• pause-threshold—Specifies the buffer limit at which the

port pauses the peer.

• xoff-size—Buffer limit for pausing, in bytes. Valid values

are 0 to 490880.

Note

On a Cisco Nexus 5020 switch, you can
configure a maximum pause-threshold value of
58860 bytes.

On a Cisco Nexus 5500 Series device, you can
configure a maximum pause-threshold value of
103360 bytes.

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Configuring Queuing and Flow Control

Configuring the Buffer Threshold for the Cisco Nexus 2148T Fabric Extender

PurposeCommand or Action

• resume-threshold—Specifies the buffer limit at which

the port resumes the peer.

• xon-size—Buffer limit at which to resume, in bytes. Valid

values are 0 to 490880.

Note

On a Cisco Nexus 5020 switch, you can
configure a maximum resume-threshold value
of 38400 bytes.

On a Cisco Nexus 5500 Series device, you can
configure a maximum resume-threshold value
of 83520 bytes.

Step 5

switch(config-pmap-nq-c)# no
pause no-drop buffer-size
buffer-size pause-threshold

(Optional)
Removes the buffer threshold settings for pause and resume
for 3000m lossless Ethernet.

xoff-size resume-threshold
xon-size

Step 6

Step 7

Exits class mode.switch(config-pmap-nq-c)# exit

Exits policy-map network-qos mode.switch(config-pmap-nq)# exit

This example shows how to configure the no-drop buffer threshold for the Cisco Nexus device for 3000
meters.

switch(config-pmap-nq)# policy-map type network-qos nqos_policy
switch(config-pmap-nq)# class type network-qos nqos_class
switch(config-pmap-nq-c)# pause no-drop buffer-size 152000 pause-threshold 103360

resume-threshold 83520

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

Configuring the Buffer Threshold for the Cisco Nexus 2148T Fabric Extender

In the Fabric Extender configuration mode, you can configure the buffer threshold for the Cisco Nexus 2148T
Fabric Extender. The buffer threshold sets the consumption level of input buffers before an indication is sent
to the egress queue to start observing the tail drop threshold. If the buffer usage is lower than the configured
buffer threshold, the tail drop threshold is ignored.

Procedure

PurposeCommand or Action

Step 1

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Enters global configuration mode.switch# configure terminal

Enabling Virtual Output Queuing Limits for Unicast Traffic on the Cisco Nexus Device

Configuring Queuing and Flow Control

PurposeCommand or Action

Step 2

switch(config)# fex fex-id

Specifies the Fabric Extender and enters the Fabric
Extender mode.

Step 3

switch(config-fex)# hardware
N2148T buffer-threshold buffer limit

Configures the buffer threshold for the Cisco Nexus
2148T Fabric Extender. The buffer threshold is specified
in bytes. The range is from 81920 to 316160 for the
Cisco Nexus 2148T Fabric Extender.

This example shows how to restore the default buffer threshold on the Cisco Nexus 2148T Fabric Extender:

switch# configure terminal
switch(config)# fex 101
switch(config-fex)# hardware N2148T buffer-threshold 163840

This example shows how to remove the default buffer threshold on the Cisco Nexus 2148T Fabric Extender:

switch# configure terminal
switch(config)# fex 101
switch(config-fex)# no hardware N2148T buffer-threshold

Enabling Virtual Output Queuing Limits for Unicast Traffic on the Cisco Nexus
Device

You can enable the Virtual Output Queuing (VOQ) limit for unicast traffic. To alleviate congestion and
blocking, use VOQ to prevent one blocked receiver from affecting traffic that is sent to other noncongested
blocking receivers.

Procedure

PurposeCommand or Action

Step 1

Step 2

switch(config)# hardware unicast voq-limit

Enters configuration mode.switch# configure terminal

Enables the VOQ limit for unicast traffic. The
default is disabled.

Step 3

Disables the VOQ limit for unicast traffic.switch(config)# no hardware unicast

voq-limit

This example shows how to enable the VOQ limits for unicast packets on a switch:

switch(config)# hardware unicast voq-limit
switch(config)#

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Configuring Queuing and Flow Control

Configuring Flow Control

Link-Level Flow Control

IEEE 802.3x link-level flow control allows a congested receiver to communicate a transmitter at the other
end of the link to pause its data transmission for a short period of time. The link-level flow control feature
applies to all the traffic on the link.

The transmit and receive directions are separately configurable. By default, link-level flow control is disabled
for both directions.

On the Cisco Nexus device, Ethernet interfaces do not automatically detect the link-level flow control capability.
You must configure the capability explicitly on the Ethernet interfaces.

On each Ethernet interface, the switch can enable either priority flow control or link-level flow control (but
not both).

Configuring Flow Control

Configuring Priority Flow Control

By default, Ethernet interfaces negotiate PFC with the network adapter using the DCBX protocol. When PFC
is enabled, PFC is applied to traffic that matches the CoS value configured for the no-drop class.

You can override the negotiation result by forcing the interface to enable PFC.

Procedure

Step 1

Step 2

Step 3

Step 4

This example shows how to force-enable PFC on an interface:

switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# priority-flow-control mode on

switch(config)# interface type slot/port

mode {auto | on}

switch(config-if)# no
priority-flow-control mode on

PurposeCommand or Action

Enters global configuration mode.switch# configure terminal

Specifies the interface to be changed.

Sets PFC mode for the selected interface.switch(config-if)# priority-flow-control

Specifies auto to negotiate PFC capability. This is
the default.

Specifies on to force-enable PFC.

(Optional)
Disables the PFC setting for the selected interface.

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Configuring Link-Level Flow Control

Configuring Link-Level Flow Control

By default, LLC on Ethernet interfaces is disabled. You can enable LLC for the transmit and receive directions.

Procedure

Configuring Queuing and Flow Control

PurposeCommand or Action

Step 1

Step 2

Step 3

Step 4

This example shows how to enable LLC on an interface:

switch# configure terminal
switch(config)# interface ethernet 1/2
switch(config-if)# flowcontrol receive on transmit on

switch(config)# interface type slot/port

switch(config-if)# flowcontrol [receive {on |
off}] [transmit {on | off}]

switch(config-if)# no flowcontrol [receive {on
| off}] [transmit {on | off}]

Enters global configuration mode.switch# configure terminal

Specifies the interface to be changed.

Enables LLC for the selected interface. Set
receive and/or transmit on or off.

(Optional)
Disables LLC for the selected interface.

Disabling Slow Port Pruning on Multicast Traffic on the Cisco Nexus 5500 Series Device

You can disable slow port pruning on multicast packets.

An interface on the Cisco Nexus 5500 Series device can become congested when it receives excessive multicast
traffic or when the mixed unicast and multicast traffic rate exceeds the port bandwidth. When multiple interfaces
receive the same multicast flow and one or more ports experience congestion, the slow port prunning feature
allows the switch to drop only the multicast packets for the congested port. This feature is turned on by default.
To turn the slow port pruning feature off, enter the hardware multicast disable-slow-port-pruning command.

Procedure

PurposeCommand or Action

Step 1

Step 2

Step 3

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switch(config)# hardware multicast
disable-slow-port-pruning

disable-slow-port-pruning

Enters configuration mode.switch# configure terminal

Disables slow port pruning on multicast
packets. The default is enabled.

Enables the slow port pruning feature.switch(config)# no hardware multicast

Configuring Queuing and Flow Control

Verifying the Queue and Flow Control Configurations

This example shows how to disable slow port pruning on a Cisco Nexus 5548 switch:

switch(config)# hardware multicast disable-slow-port-pruning
switch(config)#

Verifying the Queue and Flow Control Configurations

Use one of the following commands to verify the configuration:

PurposeCommand

show queuing interface [interface slot/\port]

show interface flowcontrol [module numbef ]

show interface [interface slot/port]
priority-flow-control [module number]

show wrr-queue cos-map [var]

running-config ipqos

startup-config ipqos

Displays the queue configuration and statistics.

Displays the detailed listing of the flow control
settings on all interfaces.

Displays the priority flow control details for a
specified interface.

Displays information about the running configuration
for QoS.

Displays informationa bout the startup configuration
for QoS.

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Verifying the Queue and Flow Control Configurations

Configuring Queuing and Flow Control

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QoS Configuration Examples

This chapter contains the following sections:

QoS Example 1 , page 69

•

QoS Example 2 , page 70

•

QoS Example 3 , page 72

•

QoS Example 1

This example shows how to configure traffic in the entire system matching an access control list to have the
frame CoS fields rewritten to the value 5.

CHAPTER 10

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QoS Example 2

QoS Configuration Examples

Procedure

PurposeCommand or Action

Step 1

Step 2

Step 3

Step 4

Set up the ingress classification policy
(the access control list was defined
previously).

Attach the classification policy to the
system.

Set up the system class allocation and
rewrite policy. Allocate the system
class for qos-group 4 and define the
rewrite action.

Attach the allocation and rewrite policy
to the system.

(config)# class-map type qos cmap-qos-acl
(config-cmap-qos)# match access-group ACL-CoS
(config-cmap-qos)# exit
(config)# policy-map type qos pmap-qos-acl
(config-pmap-qos)# class cmap-qos-acl
(config-pmap-c-qos)# set qos-group 4
(config-pmap-c-qos)# exit
(config-pmap-qos)# exit

(config)# system qos
(config-sys-qos)# service-policy type qos input

pmap-qos-acl

(config-sys-qos)# exit

(config)# class-map type network-qos cmap-nq-acl
(config-cmap-nq)# match qos-group 4
(config-cmap-nq)# exit
(config)# policy-map type network-qos pmap-nq-acl
(config-pmap-nq)# class type network-qos

cmap-nq-acl

(config-pmap-c-nq)# set cos 5
(config-pmap-c-nq)# exit
(config-pmap-nq)# exit

(config)# system qos
(config-sys-qos)# service-policy type network-qos

pmap-nq-acl

(config-sys-qos)# exit

QoS Example 2

This example shows how to use an access control list to apply 50% bandwidth to traffic on Ethernet interface
1/3 that matches traffic on Ethernet interface 1/1.

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QoS Configuration Examples

Procedure

QoS Example 2

PurposeCommand or Action

Step 1

Step 2

Step 3

Step 4

Set up the ingress classification
policy.

Attach the classification policy
to the interface Ethernet 1/1.

Set up the system-wide
definition of the qos-group first.

Set up the egress bandwidth
policy.

(config)# class-map type qos cmap-qos-bandwidth
(config-cmap-qos)# match access-group ACL-bandwidth
(config-cmap-qos)# exit
(config)# policy-map type qos pmap-qos-eth1-1
(config-pmap-qos)# class cmap-qos-bandwidth
(config-pmap-c-qos)# set qos-group 2
(config-pmap-c-qos)# exit
(config-pmap-qos)# exit

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

pmap-qos-eth1-1

(config-if)# exit

(config)# class-map type queuing cmap-que-bandwidth
(config-cmap-que)# match qos-group 2
(config-cmap-que)# exit

Note

Before you can successfully allocate bandwidth to the
user-defined class cmap-que-bandwidth, you must first
reduce the default bandwidth configuration on
class-default and class-fcoe.

(config)# policy-map type queuing pmap-que-eth1-2
(config-pmap-que)# class type queuing class-default
(config-pmap-c-que)# bandwidth percent 10
(config-pmap-c-que)# exit
(config-pmap-que)# class type queuing class-fcoe
(config-pmap-c-que)# bandwidth percent 40
(config-pmap-c-que)# exit
(config-pmap-que)# class type queuing

cmap-que-bandwidth

(config-pmap-c-que)# bandwidth percent 50
(config-pmap-c-que)# exit
(config-pmap-que)# exit

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QoS Example 3

QoS Configuration Examples

PurposeCommand or Action

Step 5

Step 6

Step 7

Step 8

Attach the bandwidth policy to
the egress interface.

Allocate the system class for
qos-group 2.

Set up the network-qos policy.

Attach the network-qos policy
to the system.

(config)# interface ethernet 1/3
(config-if)# service-policy type queuing output

pmap-que-eth1-2

(config-if)# exit

(config)# class-map type network-qos cmap-nq-bandwidth
(config-cmap-nq)# match qos-group 2
(config-cmap-nq)# exit

(config)# policy-map type network-qos pmap-nq-bandwidth
(config-pmap-nq)# class type network-qos

cmap-nq-bandwidth

(config-pmap-c-nq)# exit
(config-pmap-nq)# exit

(config)# system qos
(config-sys-qos)# service-policy type network-qos

pmap-nq-bandwidth
(config-sys-qos)# exit

QoS Example 3

This example shows how to attach a 802.1p tag with a CoS value of 3 to incoming untagged packets, and
force priority-flow-control negotiation on Ethernet interface 1/15.

Procedure

Step 1

Set up the ingress classification policy (the
access control list was defined previously).

PurposeCommand or Action

(config)# interface Ethernet 1/15

(config-if)# untagged cos 3

(config-if)# priority-flow-control mode

on

(config-if)# exit

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INDEX

A

attaching 37

system service policy 37

C

changed information 1

description 1

Cisco Nexus devices 64

virtual output queuing limits 64

class maps 8

configuring 8

classification 7, 8

information about 7
licensing requirements 8

classification configuration 16

verifying 16

classification policies 8

ingress 8

configuring 22, 27, 29, 45, 62, 65, 66

DSCP marking 27
interface service policies 45
IP precedence marking 29
link-level flow control 66
no-drop buffer thresholds 62
priority flow control 65

type network QoS policies 22
Configuring type queuing policies 23
configuring untagged CoS 45
CoS marking 30, 31

configuring 30

layer 3 31
CPU traffic 5

QoS 5

D

default system service policies 38

restoring 38

DSCP classification 12

configuring 12

E

enabling 40

jumbo MTU 40

F

feature history 56

VLAN QoS 56

Fibre Channel interfaces 44

policy 44

flow control 67

verifying 67

G

guidelines and limitations 52

VLAN QoS 52

I

information about 7, 17, 35, 49

classification 7
policy types 17
system classes 35
VLAN QoS 49

ingress 8

classification policies 8

interface QoS configuration 47

verifying 47

interface QoS policies 50

precedence of 50

interface QoS TCAM limit 53, 54

changing 53

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Index

interface QoS TCAM limit (continued)

configuring 53
removing 54

IP precedence marking 29

configuring 29

J

jumbo MTU 41

verifying 41

L

layer 3 31

CoS marking 31

licensing requirements 8

classification 8

M

marking 27

information about 27

marking configuration 32

verifying 32
modular QoS CLI 3
MQC 3
MTU 36
multicast traffic 44

QoS 44

policy maps 19

creating 19

policy types 17

information about 17

precedence 50, 51

interface QoS policies 50
system QoS policies 50
VACL and VLAN QoS policies 51
VLAN QoS and VACL policies 51
VLAN QoS policies 50

precedence classification 10

configuring 10

Q

Qos 5, 44

CPU traffic 5
multicast traffic 44

QoS 10, 12

DSCP classification 12

configuring 12

precedence classification 10

configuring 10

quality of service 3

overview 3
Quality of Service, See QoS
queuq configuration 67

verifying 67

R

restoring 38

default system service policies 38

N

new information 1

description 1

O

overview 3

quality of service 3

P

policy 44

Fibre Channel interfaces 44

policy map configuration 24

verifying 24

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S

service policies 55

removing from a VLAN 55
system classes 35

information about 35
system QoS configuration 41

verifying 41
system QoS policies 50

precedence of 50
system service policy 37

attaching 37

Index

T

TCAM carving 52

VLAN QoS 52

type QoS polices, configuring 21

U

unicast traffic 64

virtual output queuing limits 64

V

VACLs 51

precedence of 51

verifying 16, 24, 32, 41, 47, 56, 67

classification configuration 16
flow control 67

verifying (continued)

interface QoS configuration 47
marking configuration 32
policy map configuration 24
queue configuration 67
system QoS configuration 41
VLAN QoS configuration 56

virtual output queuing limits 64

unicast traffic 64

VLAN QoS 52, 56

feature history 56
guidelines and limitations 52
TCAM carving 52

VLAN QoS configuration 56

verifying 56

VLAN QoS policies 50, 51

precedence of 50, 51

VLANs 49, 55

QoS 49
removing a service policy from 55

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Index

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