15-QoS Configuration Guide

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02-QoS configuration
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Contents

QoS overview·· 1

QoS service models· 1

Best-effort service model 1

IntServ model 1

DiffServ model 1

QoS techniques in a network· 1

QoS processing flow in a device· 2

QoS configuration approaches· 3

Configuring a QoS policy· 4

About QoS policies· 4

QoS policy tasks at a glance· 4

Defining a traffic class· 4

Defining a traffic behavior 4

Defining a QoS policy· 5

Applying the QoS policy· 5

Application destinations· 5

Restrictions and guidelines for applying a QoS policy· 5

Applying the QoS policy to an interface· 5

Applying the QoS policy to a user profile· 6

Display and maintenance commands for QoS policies· 6

Configuring priority mapping· 8

About priority mapping· 8

About priorities· 8

Priority maps· 8

Priority mapping configuration methods· 8

Priority mapping process· 9

Priority mapping tasks at a glance· 10

Configuring a priority map· 10

Configuring a port to trust packet priority for priority mapping· 10

Changing the port priority of an interface· 11

Display and maintenance commands for priority mapping· 11

Configuring traffic policing· 12

About traffic policing· 12

Traffic evaluation and token buckets· 12

Traffic policing· 12

Configuring traffic policing· 13

Traffic policing configuration approaches· 13

Configuring traffic policing by using the MQC approach· 13

Configuring traffic policing for a user profile· 14

Display and maintenance commands for traffic policing· 15

Configuring traffic filtering· 16

About traffic filtering· 16

Restrictions and guidelines: Traffic filtering configuration· 16

Procedure· 16

Configuring priority marking· 18

About priority marking· 18

Configuring priority marking· 18

Priority marking configuration examples· 19

Example: Configuring priority marking· 19

Appendixes· 22

Appendix A Acronyms· 22

Appendix B Default priority maps· 23

Appendix C Introduction to packet precedence· 24

IP precedence and DSCP values· 24

802.1p priority· 26

802.11e priority· 26

 


QoS overview

In data communications, Quality of Service (QoS) provides differentiated service guarantees for diversified traffic in terms of bandwidth, delay, jitter, and drop rate, all of which can affect QoS.

QoS manages network resources and prioritizes traffic to balance system resources.

The following section describes typical QoS service models and widely used QoS techniques.

 

QoS service models

This section describes several typical QoS service models.

Best-effort service model

The best-effort model is a single-service model. The best-effort model is not as reliable as other models and does not guarantee delay-free delivery.

The best-effort service model is the default model for the Internet and applies to most network applications. It uses the First In First Out (FIFO) queuing mechanism.

IntServ model

The integrated service (IntServ) model is a multiple-service model that can accommodate diverse QoS requirements. This service model provides the most granularly differentiated QoS by identifying and guaranteeing definite QoS for each data flow.

In the IntServ model, an application must request service from the network before it sends data. IntServ signals the service request with the RSVP. All nodes receiving the request reserve resources as requested and maintain state information for the application flow.

The IntServ model demands high storage and processing capabilities because it requires all nodes along the transmission path to maintain resource state information for each flow. This model is suitable for small-sized or edge networks. However, it is not suitable for large-sized networks, for example, the core layer of the Internet, where billions of flows are present.

DiffServ model

The differentiated service (DiffServ) model is a multiple-service model that can meet diverse QoS requirements. It is easy to implement and extend. DiffServ does not signal the network to reserve resources before sending data, as IntServ does.

QoS techniques in a network

The QoS techniques include the following features:

·     Traffic classification.

·     Traffic policing.

The following section briefly introduces these QoS techniques.

All QoS techniques in this document are based on the DiffServ model.

Figure 1 Position of the QoS techniques in a network

As shown in Figure 1, traffic classification and traffic policing mainly implement the following functions:

·     Traffic classification—Uses match criteria to assign packets with the same characteristics to a traffic class. Based on traffic classes, you can provide differentiated services.

·     Traffic policing—Polices flows and imposes penalties to prevent aggressive use of network resources. You can apply traffic policing to both incoming and outgoing traffic of a port.

QoS processing flow in a device

Figure 2 briefly describes how the QoS module processes traffic.

1.     Traffic classifier identifies and classifies traffic for subsequent QoS actions.

2.     The QoS module takes various QoS actions on classified traffic as configured, depending on the traffic processing phase and network status. For example, you can configure traffic policing for incoming traffic.

Figure 2 QoS processing flow

QoS configuration approaches

You can configure QoS by using the MQC approach or non-MQC approach.

In the modular QoS configuration (MQC) approach, you configure QoS service parameters by using QoS policies. A QoS policy defines QoS actions to take on different classes of traffic and can be applied to an object (such as an interface) to control traffic.

In the non-MQC approach, you configure QoS service parameters without using a QoS policy.

Some features support both approaches, but some support only one.

 


Configuring a QoS policy

About QoS policies

A QoS policy has the following components:

·     Traffic class—Defines criteria to match packets.

·     Traffic behavior—Defines QoS actions to take on matching packets.

By associating a traffic class with a traffic behavior, a QoS policy can perform the QoS actions on matching packets.

A QoS policy can have multiple class-behavior associations.

 

QoS policy tasks at a glance

To configure a QoS policy, perform the following tasks:

1.     Defining a traffic class

2.     Defining a traffic behavior

3.     Defining a QoS policy

4.     Applying the QoS policy

¡     Applying the QoS policy to an interface

¡     Applying the QoS policy to a user profile

Defining a traffic class

1.     Enter system view.

system-view

2.     Create a traffic class and enter traffic class view.

traffic classifier classifier-name [ operator { and | or } ]

3.     Configure a match criterion.

if-match [ not ] match-criteria

By default, no match criterion is configured.

For more information, see the if-match command in ACL and QoS Command Reference.

Defining a traffic behavior

1.     Enter system view.

system-view

2.     Create a traffic behavior and enter traffic behavior view.

traffic behavior behavior-name

3.     Configure an action in the traffic behavior.

By default, no action is configured for a traffic behavior.

For more information about configuring an action, see the subsequent chapters for traffic policing, traffic filtering, priority marking, and so on.

Defining a QoS policy

1.     Enter system view.

system-view

2.     Create a QoS policy and enter QoS policy view.

qos policy policy-name

3.     Associate a traffic class with a traffic behavior to create a class-behavior association in the QoS policy.

classifier classifier-name behavior behavior-name [ insert-before before-classifier-name ]

By default, a traffic class is not associated with a traffic behavior.

Repeat this step to create more class-behavior associations.

Applying the QoS policy

Application destinations

You can apply a QoS policy to the following destinations:

·     Interface—The QoS policy takes effect on the traffic sent or received on the interface.

·     User profile—The QoS policy takes effect on the traffic sent or received by the online users of the user profile.

Restrictions and guidelines for applying a QoS policy

You can modify traffic classes, traffic behaviors, and class-behavior associations in a QoS policy even after it is applied (except that it is applied to a user profile). If a traffic class uses an ACL for traffic classification, you can delete or modify the ACL.

Applying the QoS policy to an interface

Restrictions and guidelines

A QoS policy can be applied to multiple interfaces. However, only one QoS policy can be applied to one direction (inbound or outbound) of an interface..

The QoS policy applied to the outgoing traffic on an interface does not regulate local packets. Local packets refer to critical protocol packets sent by the local system for operation maintenance. The most common local packets include link maintenance, and SSH packets.

Procedure

1.     Enter system view.

system-view

2.     Enter interface view.

interface interface-type interface-number

3.     Apply the QoS policy to the interface.

qos apply policy policy-name { inbound | outbound }

By default, no QoS policy is applied to an interface.

Applying the QoS policy to a user profile

About this task

When a user profile is configured, you can perform traffic policing based on users. After a user passes authentication, the authentication server sends the name of the user profile associated with the user to the device. The QoS policy configured in user profile view takes effect only when users come online.

Restrictions and guidelines

You can apply a QoS policy to multiple user profiles. In one direction of each user profile, only one policy can be applied. To modify a QoS policy already applied to a direction, first remove the applied QoS policy.

Procedure

1.     Enter system view.

system-view

2.     Enter user profile view.

user-profile profile-name

3.     Apply the QoS policy to the user profile.

qos apply policy policy-name { inbound | outbound }

By default, no QoS policy is applied to a user profile.

 

Parameter

Description

inbound

Applies a QoS policy to the traffic received by the device from the user profile.

outbound

Applies a QoS policy to the traffic sent by the device to the user profile.

 

Display and maintenance commands for QoS policies

Execute display commands in any view and reset commands in user view.

 

Task

Command

Display QoS policy configuration.

display qos policy { system-defined | user-defined } [ policy-name [ classifier classifier-name ] ]

Display information about QoS policies applied to interfaces.

display qos policy interface [ interface-type interface-number ] [ inbound | outbound ]

Display information about QoS policies applied to user profiles.

display qos policy user-profile [ name profile-name ] [ user-id user-id ] [ inbound | outbound ]

Display traffic behavior configuration.

display traffic behavior { system-defined | user-defined } [ behavior-name ]

Display traffic class configuration.

display traffic classifier { system-defined | user-defined }

 

 


Configuring priority mapping

About priority mapping

When a packet arrives, a device assigns a set of QoS priority parameters to the packet based on either of the following:

·     A priority field carried in the packet.

·     The port priority of the incoming port.

This process is called priority mapping. During this process, the device can modify the priority of the packet according to the priority mapping rules. The set of QoS priority parameters decides the scheduling priority and forwarding priority of the packet.

Priority mapping is implemented with priority maps and involves the following priorities:

·     802.11e priority.

·     802.1p priority.

·     DSCP.

·     IP precedence.

·     Local precedence.

·     Drop priority.

About priorities

Priorities include the following types: priorities carried in packets, and priorities locally assigned for scheduling only.

Packet-carried priorities include 802.1p priority, DSCP precedence, IP precedence, and EXP. These priorities have global significance and affect the forwarding priority of packets across the network. For more information about these priorities, see "Appendix C Introduction to packet precedence."

Locally assigned priorities only have local significance. They are assigned by the device only for scheduling. The device supports only local precedence for locally assigned priorities. A local precedence value corresponds to an output queue. A packet with higher local precedence is assigned to a higher priority output queue to be preferentially scheduled.

Priority maps

The device provides various types of priority maps. By looking through a priority map, the device decides which priority value to assign to a packet for subsequent packet processing.

The default priority maps (as shown in Appendix B Default priority maps) are available for priority mapping. They are adequate in most cases. If a default priority map cannot meet your requirements, you can modify the priority map as required.

Priority mapping configuration methods

You can configure priority mapping by using any of the following methods:

·     Configuring priority trust mode—In this method, you can configure a port to look up a trusted priority type (802.1p, for example) in incoming packets in the priority maps. Then, the system maps the trusted priority to the target priority types and values.

·     Changing port priority—If no packet priority is trusted, the port priority of the incoming port is used. By changing the port priority of a port, you change the priority of the incoming packets on the port.

Priority mapping process

On receiving an Ethernet packet on a port, the switch marks the scheduling priorities (local precedence and drop precedence) for the Ethernet packet. This procedure is done according to the priority trust mode of the receiving port and the 802.1Q tagging status of the packet, as shown in Figure 3.

Figure 3 Priority mapping process for an Ethernet packet

For information about priority marking, see "Configuring priority marking."

Priority mapping tasks at a glance

To configure priority mapping, perform the following tasks:

1.     (Optional.) Configuring a priority map

2.     Configuring a priority mapping method:

¡     Configuring a port to trust packet priority for priority mapping

¡     Changing the port priority of an interface

Configuring a priority map

1.     Enter system view.

system-view

2.     Enter priority map view.

qos map-table [ inbound | outbound ] { dot11e-lp | dot1p-lp | dscp-lp | lp-dot11e | lp-dot1p | lp-dscp }

3.     Configure mappings for the priority map.

import import-value-list export export-value

By default, the default priority maps are used. For more information, see "Appendix B Default priority maps."

If you execute this command multiple times, the most recent configuration takes effect.

Configuring a port to trust packet priority for priority mapping

About this task

You can configure the device to trust a particular priority field carried in packets for priority mapping on ports or globally. When you configure the trusted packet priority type on an interface, use the following available keywords:

·     dot1p—Uses the 802.1p priority of received packets for mapping.

·     dscp—Uses the DSCP precedence of received IP packets for mapping.

Procedure

1.     Enter system view.

system-view

2.     Enter interface view.

interface interface-type interface-number

3.     Configure the trusted packet priority type.

qos trust { dot1p | dscp }

By default, an interface does not trust any packet priority and uses the port priority as the 802.1p priority for mapping.

4.     Return to system view.

quit

Changing the port priority of an interface

About this task

If an interface does not trust any packet priority, the device uses its port priority to look for priority parameters for the incoming packets. By changing port priority, you can prioritize traffic received on different interfaces.

Procedure

1.     Enter system view.

system-view

2.     Enter interface view.

interface interface-type interface-number

3.     Set the port priority of the interface.

qos priority priority-value

The default setting is 0.

Display and maintenance commands for priority mapping

Execute display commands in any view.

 

Task

Command

Display priority map configuration.

display qos map-table [ inbound | outbound ] [ dot11e-lp | dot1p-lp | dscp-lp | lp-dot11e | lp-dot1p | lp-dscp ]

Display the trusted packet priority type on a port.

display qos trust interface [ interface-type interface-number ]

 

 


Configuring traffic policing

About traffic policing

Traffic limit helps assign network resources (including bandwidth) and increase network performance. For example, you can configure a flow to use only the resources committed to it in a certain time range. This avoids network congestion caused by burst traffic.

Traffic policing controls the traffic rate and resource usage according to traffic specifications. You can use token buckets for evaluating traffic specifications.

Traffic evaluation and token buckets

Token bucket features

A token bucket is analogous to a container that holds a certain number of tokens. Each token represents a certain forwarding capacity. The system puts tokens into the bucket at a constant rate. When the token bucket is full, the extra tokens cause the token bucket to overflow.

Evaluating traffic with the token bucket

A token bucket mechanism evaluates traffic by looking at the number of tokens in the bucket. If the number of tokens in the bucket is enough for forwarding the packets:

·     The traffic conforms to the specification (called conforming traffic).

·     The corresponding tokens are taken away from the bucket.

Otherwise, the traffic does not conform to the specification (called excess traffic).

A token bucket has the following configurable parameters:

·     Mean rate at which tokens are put into the bucket, which is the permitted average rate of traffic. It is usually set to the committed information rate (CIR).

·     Burst size or the capacity of the token bucket. It is the maximum traffic size permitted in each burst. It is usually set to the committed burst size (CBS). The set burst size must be greater than the maximum packet size.

Each arriving packet is evaluated.

Complicated evaluation

The token bucket mechanism can have two token buckets, bucket C and bucket E, to evaluate traffic in a more complicated environment and achieve more policing flexibility. Traffic policing uses the single rate two color algorithm, which uses one token bucket and the following parameters:

·     CIR—Rate at which tokens are put into bucket C. It sets the average packet transmission or forwarding rate allowed by bucket C.

·     CBS—Size of bucket C, which specifies the transient burst of traffic that bucket C can forward.

When a packet arrives, the following rules apply:

·     If bucket C has enough tokens to forward the packet, the packet is colored green.

·     Otherwise, the packet is colored red.

Traffic policing

Traffic policing supports policing the inbound traffic and the outbound traffic.

A typical application of traffic policing is to supervise the specification of traffic entering a network and limit it within a reasonable range. Another application is to "discipline" the extra traffic to prevent aggressive use of network resources by an application. For example, you can limit bandwidth for HTTP packets to less than 50% of the total. If the traffic of a session exceeds the limit, traffic policing can drop the packets or reset the IP precedence of the packets. Figure 4 shows an example of policing outbound traffic on an interface.

Figure 4 Traffic policing

 

Traffic policing is widely used in policing traffic entering the ISP networks. It can classify the policed traffic and take predefined policing actions on each packet depending on the evaluation result:

·     Forwarding the packet if the evaluation result is "conforming."

·     Dropping the packet if the evaluation result is "excess."

·     Forwarding the packet with its precedence re-marked if the evaluation result is "conforming."

Configuring traffic policing

Traffic policing configuration approaches

You can configure traffic policing by using the MQC approach or the non-MQC approach. If both approaches are used, the MQC configuration takes effect.

You can configure user profile-based traffic policing by using the non-MQC approach.

If traffic policing is configured by using both the MQC approach and non-MQC approach, the configuration in MQC approach takes effect.

Configuring traffic policing by using the MQC approach

Restrictions and guidelines

The device supports applying traffic policing to an interface or user profile.

Procedure

1.     Enter system view.

system-view

2.     Define a traffic class.

a.     Create a traffic class and enter traffic class view.

traffic classifier classifier-name [ operator { and | or } ]

b.     Configure a match criterion.

if-match [ not ] match-criteria

By default, no match criterion is configured.

For more information about the if-match command, see ACL and QoS Command Reference.

c.     Return to system view.

quit

3.     Define a traffic behavior.

a.     Create a traffic behavior and enter traffic behavior view.

traffic behavior behavior-name

b.     Configure a traffic policing action.

car cir committed-information-rate [ cbs committed-burst-size ] [ green action | red action | yellow action ] *

By default, no traffic policing action is configured.

c.     Return to system view.

quit

4.     Define a QoS policy.

a.     Create a QoS policy and enter QoS policy view.

qos policy policy-name

b.     Associate the traffic class with the traffic behavior in the QoS policy.

classifier classifier-name behavior behavior-name

By default, a traffic class is not associated with a traffic behavior.

c.     Return to system view.

quit

5.     Apply the QoS policy.

For more information, see "Applying the QoS policy."

By default, no QoS policy is applied.

Configuring traffic policing for a user profile

About this task

When a user profile is configured, you can perform traffic policing based on users. After a user passes authentication, the authentication server sends the name of the user profile associated with the user to the device. When any user of the user profile logs in, the authentication server automatically applies the CAR parameters configured for the user profile to the user. When the user logs off, the system automatically removes the CAR configuration without manual intervention.

Procedure

1.     Enter system view.

system-view

2.     Enter user profile view.

user-profile profile-name

3.     Configure a CAR policy for the user profile.

qos car { inbound | outbound } any cir committed-information-rate [ cbs committed-burst-size ]

By default, no CAR policy is configured for a user profile.

Display and maintenance commands for traffic policing

Execute display commands in any view.

 

Task

Command

Display traffic behavior configuration.

display traffic behavior user-defined [ behavior-name ]


Configuring traffic filtering

About traffic filtering

You can filter in or filter out traffic of a class by associating the class with a traffic filtering action. For example, you can filter packets sourced from an IP address according to network status.

Restrictions and guidelines: Traffic filtering configuration

The device supports applying traffic filtering to an interface or user profile.

Procedure

1.     Enter system view.

system-view

2.     Define a traffic class.

a.     Create a traffic class and enter traffic class view.

traffic classifier classifier-name [ operator { and | or } ]

b.     Configure a match criterion.

if-match [ not ] match-criteria

By default, no match criterion is configured.

For more information about configuring match criteria, see ACL and QoS Command Reference.

c.     Return to system view.

quit

3.     Define a traffic behavior.

a.     Create a traffic behavior and enter traffic behavior view.

traffic behavior behavior-name

b.     Configure the traffic filtering action.

filter { deny | permit }

By default, no traffic filtering action is configured.

If a traffic behavior has the filter deny action, all other actions in the traffic behavior except class-based accounting do not take effect.

c.     Return to system view.

quit

4.     Define a QoS policy.

a.     Create a QoS policy and enter QoS policy view.

qos policy policy-name

b.     Associate the traffic class with the traffic behavior in the QoS policy.

classifier classifier-name behavior behavior-name

By default, a traffic class is not associated with a traffic behavior.

c.     Return to system view.

quit

5.     Apply the QoS policy.

For more information, see "Applying the QoS policy."

By default, no QoS policy is applied.

6.     (Optional.) Display the traffic filtering configuration.

display traffic behavior user-defined [ behavior-name ]

This command is available in any view.


Configuring priority marking

About priority marking

Priority marking sets the priority fields or flag bits of packets to modify the priority of packets. For example, you can use priority marking to set IP precedence or DSCP for a class of IP packets to control the forwarding of these packets.

To configure priority marking to set the priority fields or flag bits for a class of packets, perform the following tasks:

1.     Configure a traffic behavior with a priority marking action.

2.     Associate the traffic class with the traffic behavior.

Priority marking can be used together with priority mapping. For more information, see "Configuring priority mapping."

Configuring priority marking

Restrictions and guidelines

The device supports applying priority marking to an interface or user profile.

Procedure

1.     Enter system view.

system-view

2.     Define a traffic class.

a.     Create a traffic class and enter traffic class view.

traffic classifier classifier-name [ operator { and | or } ]

b.     Configure a match criterion.

if-match [ not ] match-criteria

By default, no match criterion is configured.

For more information about the if-match command, see ACL and QoS Command Reference.

c.     Return to system view.

quit

3.     Define a traffic behavior.

a.     Create a traffic behavior and enter traffic behavior view.

traffic behavior behavior-name

b.     Configure a priority marking action.

For configurable priority marking actions, see the  remark commands in ACL and QoS Command Reference.

c.     Return to system view.

quit

4.     Define a QoS policy.

a.     Create a QoS policy and enter QoS policy view.

qos policy policy-name

b.     Associate the traffic class with the traffic behavior in the QoS policy.

classifier classifier-name behavior behavior-name

By default, a traffic class is not associated with a traffic behavior.

c.     Return to system view.

quit

5.     Apply the QoS policy.

For more information, see "Applying the QoS policy."

By default, no QoS policy is applied.

6.     (Optional.) Display the priority marking configuration.

display traffic behavior user-defined [ behavior-name ]

This command is available in any view.

Priority marking configuration examples

Example: Configuring priority marking

Network configuration

As shown in Figure 5, configure priority marking on the AP to process traffic from the client as follows:

 

Destination

Processing priority

Data server

High

Mail server

Medium

File server

Low

Figure 5 Network diagram

Procedure

# Create advanced ACL 3000, and configure a rule to match packets with destination IP address 192.168.0.1.

<AP> system-view

[AP] acl advanced 3000

[AP-acl-ipv4-adv-3000] rule permit ip destination 192.168.0.1 0

[AP-acl-ipv4-adv-3000] quit

# Create advanced ACL 3001, and configure a rule to match packets with destination IP address 192.168.0.2.

[AP] acl advanced 3001

[AP-acl-ipv4-adv-3001] rule permit ip destination 192.168.0.2 0

[AP-acl-ipv4-adv-3001] quit

# Create advanced ACL 3002, and configure a rule to match packets with destination IP address 192.168.0.3.

[AP] acl advanced 3002

[AP-acl-ipv4-adv-3002] rule permit ip destination 192.168.0.3 0

[AP-acl-ipv4-adv-3002] quit

# Create a traffic class named classifier_dbserver, and use ACL 3000 as the match criterion in the traffic class.

[AP] traffic classifier classifier_dbserver

[AP-classifier-classifier_dbserver] if-match acl 3000

[AP-classifier-classifier_dbserver] quit

# Create a traffic class named classifier_mserver, and use ACL 3001 as the match criterion in the traffic class.

[AP] traffic classifier classifier_mserver

[AP-classifier-classifier_mserver] if-match acl 3001

[AP-classifier-classifier_mserver] quit

# Create a traffic class named classifier_fserver, and use ACL 3002 as the match criterion in the traffic class.

[AP] traffic classifier classifier_fserver

[AP-classifier-classifier_fserver] if-match acl 3002

[AP-classifier-classifier_fserver] quit

# Create a traffic behavior named behavior_dbserver, and configure the action of setting the DSCP value to 4.

[AP] traffic behavior behavior_dbserver

[AP-behavior-behavior_dbserver] remark dscp 4

[AP-behavior-behavior_dbserver] quit

# Create a traffic behavior named behavior_mserver, and configure the action of setting the DSCP value to 3.

[AP] traffic behavior behavior_mserver

[AP-behavior-behavior_mserver] remark dscp 3

[AP-behavior-behavior_mserver] quit

# Create a traffic behavior named behavior_fserver, and configure the action of setting the DSCP value to 2.

[AP] traffic behavior behavior_fserver

[AP-behavior-behavior_fserver] remark dscp 2

[AP-behavior-behavior_fserver] quit

# Create a QoS policy named policy_server, and associate traffic classes with traffic behaviors in the QoS policy.

[AP] qos policy policy_server

[AP-qospolicy-policy_server] classifier classifier_dbserver behavior behavior_dbserver

[AP-qospolicy-policy_server] classifier classifier_mserver behavior behavior_mserver

[AP-qospolicy-policy_server] classifier classifier_fserver behavior behavior_fserver

[AP-qospolicy-policy_server] quit

# Apply QoS policy policy_server to the outgoing traffic of GigabitEthernet 1/0/1.

[AP] interface gigabitethernet 1/0/1

[AP-GigabitEthernet1/0/1] qos apply policy policy_server outbound

[AP-GigabitEthernet1/0/1] quit

 

 


Appendixes

Appendix A Acronyms

Table 1 Appendix A Acronyms

Acronym

Full spelling

AF

Assured Forwarding

BE

Best Effort

BQ

Bandwidth Queuing

CAR

Committed Access Rate

CBS

Committed Burst Size

CBQ

Class Based Queuing

CE

Congestion Experienced

CIR

Committed Information Rate

CQ

Custom Queuing

DCBX

Data Center Bridging Exchange Protocol

DiffServ

Differentiated Service

DSCP

Differentiated Services Code Point

EBS

Excess Burst Size

ECN

Explicit Congestion Notification

EF

Expedited Forwarding

FIFO

First in First out

FQ

Fair Queuing

GMB

Guaranteed Minimum Bandwidth

GTS

Generic Traffic Shaping

IntServ

Integrated Service

ISP

Internet Service Provider

LLQ

Low Latency Queuing

LSP

Label Switched Path

MPLS

Multiprotocol Label Switching

PE

Provider Edge

PIR

Peak Information Rate

PQ

Priority Queuing

PW

Pseudowire

QoS

Quality of Service

QPPB

QoS Policy Propagation Through the Border Gateway Protocol

RED

Random Early Detection

RSVP

Resource Reservation Protocol

RTP

Real-Time Transport Protocol

SP

Strict Priority

ToS

Type of Service

VoIP

Voice over IP

VPN

Virtual Private Network

WFQ

Weighted Fair Queuing

WRED

Weighted Random Early Detection

WRR

Weighted Round Robin

 

Appendix B Default priority maps

Table 2 Default dot1p-lp priority map

dot1p

lp

0

2

1

0

2

1

3

3

4

4

5

5

6

6

7

7

Table 3 Default dot11e-lp priority map

dot11e

lp

0

2

1

0

2

1

3

3

4

4

5

5

6

6

7

7

 

Table 4 Default dscp-lp priority map

dscp

lp

0 to 7

0

8 to 15

1

16 to 23

2

24 to 31

3

32 to 39

4

40 to 47

5

48 to 55

6

56 to 63

7

Table 5 Default lp-dot1p, lp-dot11e, and lp-dscp priority maps

Input priority value

lp-dot1p map

lp-dot11e map

lp-dscp map

lp

dot1p

dot11e

dscp

0

1

1

0

1

2

2

8

2

0

0

16

3

3

3

24

4

4

4

32

5

5

5

40

6

6

6

48

7

7

7

56

Appendix C Introduction to packet precedence

IP precedence and DSCP values

Figure 6 ToS and DS fields

 

As shown in Figure 6, the ToS field in the IP header contains 8 bits. The first 3 bits (0 to 2) represent IP precedence from 0 to 7. According to RFC 2474, the ToS field is redefined as the differentiated services (DS) field. A DSCP value is represented by the first 6 bits (0 to 5) of the DS field and is in the range 0 to 63. The remaining 2 bits (6 and 7) are reserved.

Table 6 IP precedence

IP precedence (decimal)

IP precedence (binary)

Description

0

000

Routine

1

001

priority

2

010

immediate

3

011

flash

4

100

flash-override

5

101

critical

6

110

internet

7

111

network

 

Table 7 DSCP values

DSCP value (decimal)

DSCP value (binary)

Description

46

101110

ef

10

001010

af11

12

001100

af12

14

001110

af13

18

010010

af21

20

010100

af22

22

010110

af23

26

011010

af31

28

011100

af32

30

011110

af33

34

100010

af41

36

100100

af42

38

100110

af43

8

001000

cs1

16

010000

cs2

24

011000

cs3

32

100000

cs4

40

101000

cs5

48

110000

cs6

56

111000

cs7

0

000000

be (default)

 

802.1p priority

802.1p priority lies in the Layer 2 header. It applies to occasions where Layer 3 header analysis is not needed and QoS must be assured at Layer 2.

Figure 7 An Ethernet frame with an 802.1Q tag header

 

As shown in Figure 7, the 4-byte 802.1Q tag header contains the 2-byte tag protocol identifier (TPID) and the 2-byte tag control information (TCI). The value of the TPID is 0x8100. Figure 8 shows the format of the 802.1Q tag header. The Priority field in the 802.1Q tag header is called 802.1p priority, because its use is defined in IEEE 802.1p. Table 8 shows the values for 802.1p priority.

Figure 8 802.1Q tag header

 

Table 8 Description on 802.1p priority

802.1p priority (decimal)

802.1p priority (binary)

Description

0

000

best-effort

1

001

background

2

010

spare

3

011

excellent-effort

4

100

controlled-load

5

101

video

6

110

voice

7

111

network-management

 

802.11e priority

To provide QoS services on WLAN, the 802.11e standard was developed. IEEE 802.11e is a MAC-layer enhancement to IEEE 802.11. IEEE 802.11e adds a 2-byte QoS control field to the 802.11e MAC frame header. The 3-bit QoS control field represents the 802.11e priority in the range of 0 to 7.

Figure 9 802.11e frame structure