Optimizing Converged Cisco Networks (ONT) · applications (hard QoS). Provides multiple service levels. RSVP is a signaling protocol to reserve resources for specified QoS parameters

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Optimizing Converged Cisco Networks (ONT)

Module 3: Implementing IP QoS


Selecting an Appropriate QoS Policy Model


Objectives

Describe 3 QoS models: best effort, IntServ and Diffserv.

Identify the strengths and weaknesses of each of the 3 QoS models.

Describe the purpose and functionality of RSVP.


Three QoS Models

Model Characteristics

Best effort No QoS is applied to packets. If it is not important when or how packets arrive, the best-effort model is appropriate.

Integrated Services

(IntServ)

Applications signal to the network that the applications require certain QoS parameters.

Differentiated Services

(DiffServ)

The network recognizes classes that require QoS.


Best-Effort Model

Internet was initially based on a best-effort packet delivery service.

Best-effort is the default mode for all traffic.

There is no differentiation among types of traffic.

Best-effort model is similar to using standard mail—―The mail will arrive when the mail arrives.‖

Benefits:

Highly scalable

No special mechanisms required

Drawbacks:

No service guarantees

No service differentiation


Integrated Services RFC1633 (IntServ) Model Operation

Ensures guaranteed delivery and predictable behavior of the network for applications (hard QoS).

Provides multiple service levels.

RSVP is a signaling protocol to reserve resources for specified QoS parameters.

The requested QoS parameters are then linked to a packet stream.

Streams are not established if the required QoS parameters cannot be met (admission control).

Intelligent queuing mechanisms needed to provide resource reservation in terms of:

Guaranteed rate (RSVP + LLQ)

Controlled load (low delay, high throughput, RSVP + WRED)


IntServ Functions

Flow Identification Packet Scheduler

Data Plane

Routing Selection Admission Control

Reservation Setup

Control Plane

Reservation Table

Queuing & schedulingClassification & Policing


Benefits and Drawbacks of the IntServ Model

Benefits:

Explicit resource admission control (end to end)

Per-request policy admission control (authorization object, policy object)

Signaling of dynamic port numbers (for example, H.323)

Drawbacks:

Continuous signaling because of stateful architecture (bandwidth overhead)

Flow-based approach not scalable to large implementations, such as the public Internet (RSVP has to track every flow)


Resource Reservation Protocol (RSVP)

Is carried in IP—protocol ID 46

Can use both TCP and UDP

port 3455

Is a signaling protocol and

works with existing routing

protocols

Requests QoS parameters

from all devices between the

source and destination

Sending Host

RSVP Receivers

RSVP Tunnel

Provides divergent performance requirements for multimedia

applications:

Rate-sensitive traffic (H.323 Videoconferencing)

Delay-sensitive traffic: controlled-delay service (non-real-time service)

predictive service (real-time service)


RSVP Daemon

PolicyControl

AdmissionControl

Packet Classifier

PacketScheduler

Routing

RSVPDaemon

Reservation

Data

Simplex flow

Sender Receiver

?

OK

Path message

Reservation


Reservation Merging (multicasting)

R1, R2 and R3 all request the same reservation.

The R2 and R3 request merges at R4.

The R1 request merges with the combined R2 and R3 request at R5.

RSVP reservation merging provides scalability.

R5R4

R3

R5 R4

R1

R2Sender


RSVP in Action

RSVP sets up a path through the network with the requested QoS.

RSVP is used for CAC in Cisco Unified CallManager 5.0.

For a voice call, a reservation in each direction is needed


The Differentiated Services Model (RFC 2474 and RFC 2475)

Overcomes many of the limitations best-effort and IntServ models

Uses the soft QoS provisioned-QoS model rather than the hard QoS

signaled-QoS model

Classifies flows into aggregates (classes) and provides appropriate

QoS for the classes (all TCP maps to one class)

Minimizes signaling and state maintenance requirements on each

network node

Manages QoS characteristics on the basis of per-hop behavior (PHB)

You choose the level of service for each traffic class (alike UPS, DHL)

Edge

Edge

Interior

Edge

DiffServ Domain

End Station

End Station


Benefits and drawbacks of the DiffServ model

Benefits:

Highly scalable

Many levels of quality possible

Drawbacks:

No absolute service guarantee

Requires a set of complex mechanisms to work in concert throughout the network


Self Check

1. Which of the QoS models is more scalable, yet still provides QoS for sensitive traffic?

2. Which QoS model relies on RSVP?

3. What are some drawbacks of using IntServ for QoS?

4. What is admission control?

5. What are the drawbacks of using Diffserv?


Summary

Best effort QoS is appropriate where sensitive traffic does not have to be serviced. When sensitive traffic must be serviced, IntServ or Diffserv should be used to provide QoS.

IntServ uses RSVP to guarantee end to end services for a traffic flow. RSVP has significant signaling overhead and is not highly scalable.

Diffserv uses classes to identify traffic and then provides QoS to those classes. Diffserv is highly scalable, but does not provide a service guarantee.


Resources

Resource Reservation Protocol (RSVP) – from the Cisco Internetworking Technology Handbook

http://cisco.com/en/US/partner/tech/tk1330/tsd_technology_support_technical_reference_chapter09186a0080759873.html

Quality of Service – from the Cisco Internetworking Technology Handbook







Using MQC for Implementing QoS


Objectives

Identify the features of each method for QoS policy implementation.

Describe the guidelines for using CLI to implement QoS policy.

Describe the Modular QoS Command Line (MQC)


Methods for Implementing QoS Policy

Method Description

Legacy CLI – Coded at the CLI

– Requires each interface to be individually configured

– Time-consuming

MQC – Coded at the CLI

– Uses configuration modules

– Best method for QoS fine tuning

Cisco AutoQoS – Applies a possible QoS configuration to the interfaces

– Fastest way to implement QoS

Cisco SDM QoS wizard – Application for simple QoS configurations


Comparing QoS Implementation Methods

Legacy CLI MQCCisco

AutoQoSCisco SDM QoS Wizard

Ease of use PoorModerately

easySimple Simple

Ability to fine-tune

Acceptable Very good Limited Limited

Time to implement

Longest Average Shortest Short

Modularity Poor Excellent Excellent Very good


Configuring QoS at the CLI

Uses the CLI via console and Telnet

Traditional method (traffic policy, apply policy to int.)

Nonmodular

Cannot separate traffic classification from policy definitions

Time-consuming and potentially error-prone task (copy-paste)

Used to augment and fine-tune newer Cisco AutoQoSmethod


Guidelines for Using the CLI Configuration Method

Build a traffic policy:

Identify the traffic pattern.

Classify the traffic.

Prioritize the traffic.

Select a proper QoS mechanism:

Queuing

Compression

Apply the traffic policy to the interface.


Legacy CLI QoS Example

For interactive traffic, you can use CQ and TCP header compression.

interface multilink

ip address 10.1.61.1 255.255.255.0

load-interval 30

custom-queue-list 1

ppp multilink

ppp multilink fragment-delay 10

ppp multilink interleave

multilink-group 1

ip tcp header-compression iphc-format

!

queue-list 1 protocol ip 2 tcp 23


Modular QoS CLI

A command syntax for configuring QoS policy

Reduces configuration steps and time

Configures policy, not ―raw‖ per-interface commands

Uniform CLI across major Cisco IOS platforms

Uniform CLI structure for all QoS features

Separates classification engine from the policy


Modular QoS CLI Components

ACL, NBAR, DSCP, MPLS EXP BIT,

IEEE802.1p

to an interface or PVC (ATM, F.R.)


Modular QoS CLI Example


Step 1: Creating Class Maps:“What Traffic Do We Care About?”

Each class is identified using a class map.

A traffic class contains three major elements:

A case-sensitive name

A series of match commands

An instruction on how to evaluate the match commands if more than one match command exists in the traffic class

Class maps can operate in two modes:

Match all: All conditions have to succeed.

Match any: At least one condition must succeed.

The default mode is match all.


match protocol

Configuring Class Maps

Enter class-map configuration mode. Specify the matching strategy.

class-map [match-all | match-any] class-map-name

router(config)#

description description

router(config-cmap)#

Use at least one condition to match packets.

Use descriptions in large and complex configurations. The description has no operational meaning.

match any


match not match-criteria

#class-map noipcmap)#match not protocol ipcmap)#exit! All protocols but ip will be in! this class

Packets that fail to meet any of the matching criteria are classified as members of the default traffic class (class-default)


Classifying Traffic with ACLs

Standard ACL

access-list access-list-number {permit | deny | remark}

source [mask]

router(config)#

access-list access-list-number {permit | deny} protocol

source source-wildcard [operator port] destination

destination-wildcard [operator port] [established] [log]

router(config)#

match access-group access-list-number


Extended ACL

Use an ACL as a match criterion


Step 2: Policy Maps: “What Will Be Done to This Traffic?”

A policy map defines a traffic policy, which configures the QoS features associated with a traffic class that was previously identified using a class map.

A traffic policy contains three major elements:

A case-sensitive name

A traffic class

The QoS policy that is associated with that traffic class

Up to 256 traffic classes can be associated with a single traffic policy.

Multiple policy maps can be nested (service-policy) to influence the sequence of QoS actions.


Configuring Policy Maps

Enter policy-map configuration mode. Policy maps are identified by a case-sensitive name.

policy-map policy-map-name

router(config)#

class {class-name | class-default}

router(config-pmap)#

condition

router(config-pmap-c)#

Enter the per-class policy configuration mode by using the name of a previously configured class map. Use the class-default name to configure the policy for the default class.

You can define the QoS policy by entering the condition after the name of the class.

• If a packet matches more than one class, the first traffic class defined in the policy is used.• All traffic not identified in any of the class maps used within the policy map, become part of the default class class-default.


Example 1: Traffic policy

Router(config)# policy-map policy1Router(config-pmap)# class class1Router(config-pmap-c)# bandwidth 3000Router(config-pmap-c)# queue-limit 30Router(config-pmap-c)# exitRouter(config-pmap)# class class2Router(config-pmap-c)# bandwidth 2000Router(config-pmap)# exit

!

! Assigning QoS to the default class

!

Router(config)# policy-map policy1Router(config-pmap)# class class-defaultRouter(config-pmap-c)# fair-queue 10Router(config-pmap-c)# queue-limit 20


Example 2: Enforcing a sub-rate

Router(config)# policy-map CHILDRouter(config-pmap)# class VOICERouter(config-pmap-c)# priority 1000Router(config-pmap-c)# class MCARouter(config-pmap-c)# bandwidth 2000Router(config-pmap-c)# class VIDEORouter(config-pmap-c)# bandwidth 5000

! NestingRouter(config)# policy-map PARENTRouter(config-pmap)# class class-defaultRouter(config-pmap-c)# shape average 10000000Router(config-pmap-c)# service-policy CHILD

• Voice: 1 Mbps• Mission critical applications traffic: 2 Mbps• Video: 5 Mbps• Remaining bandwidth allocated to best-effort traffic within the defined 10 Mbps pipe


Step 3: Attaching Service Policies: “Where Will This Policy Be Implemented?”

Attach the specified service policy map to the input or output interface, like an ACL (only one per direction)

service-policy {input | output} policy-map-name

router(config-if)#

class-map HTTP

match protocol http

!

policy-map PM

class HTTP

bandwidth 2000

class class-default

bandwidth 6000

!

interface Serial0/0

service-policy output PM

Service policies can be applied to an interface for inbound or outbound packets


Modular QoS CLI Configuration Example

router(config)# class-map match-any business-critical-trafficrouter(config-cmap)# match protocol http url “*customer*”router(config-cmap)# match protocol http url citrix

router(config)# policy-map myqos policyrouter(config-pm am)# class business-critical-trafficrouter(config-pm am-c)# bandwidth 1000

router(config)# interface serial 0/0router(config-if)# service-policy output myqos policy

1

2

3


Boolean Nesting

Goal: Find books that cover the salaries of either football players or hockey players.

Solution: Boolean (salaries AND [football players OR hockey players]).

Salaries

HockeyPlayers

Football

Players

Goal

Use a match class-mapof one class-map type (AND, OR) inside another class-map of the opposite type


Router(config)# class-map match-any class2Router(config-cmap)# match protocol ipRouter(config-cmap)# match qos-group 3Router(config-cmap)# match access-group 2Router(config-cmap)# exit

!

Router(config)# class-map match-all class1Router(config-cmap)# match class-map class2Router(config-cmap)# match destination-address mac 1.1.1Router(config-cmap)# exit

Example of boolean nesting (AND [OR])


Router(config)# class-map match-all class3Router(config-cmap)# match protocol ipRouter(config-cmap)# match qos-group 4Router(config-cmap)# exit

!

Router(config)# class-map match-any class4Router(config-cmap)# match class-map class3Router(config-cmap)# match destination-address mac 1.1.1Router(config-cmap)# match access-group 2Router(config-cmap)# exit

!

Router(config)# policy-map policy1Router(config-pmap)# class class4Router(config-pmap-c)# police 8100 1500 2504 conform-action transmit exceed-action set-qos-transmit 4Router(config-pmap-c)# exit

Example of boolean nesting (OR [AND])


MQC Example

Voice traffic needs priority, low delay, and constant bandwidth.

Interactive traffic needs bandwidth and low delay.


MQC Configuration

hostname Office

!

class-map VoIP

match access-group 100

class-map Application

match access-group 101

!

policy-map QoS-Policy

class VoIP

priority 100

class Application

bandwidth 25

class class-default

fair-queue

!

interface Serial0/0

service-policy output QoS-Policy

!

access-list 100 permit ip any any precedence 5

access-list 100 permit ip any any dscp ef

access-list 101 permit tcp any host 10.1.10.20

access-list 101 permit tcp any host 10.1.10.40

Classification

QoS Policy

QoS Policy on Interface

Classification


Basic Verification Commands

Display the class maps

show class-map

router#

show policy-map

router#

show policy-map interface type number

router#

Display the policy maps

Display the applied policy map on the interface


Summary

There are 4 basic ways to implement QoS policy on Cisco devices: CLI, MQC, AutoQoS and SDM. Choosing a method will depend on the complexity of the network on the expertise of the administrator.

The Cisco MQC offers significant advantages over the legacy CLI method for implementing QoS. By using MQC, a network administrator can significantly reduce the time and effort it takes to configure QoS in a complex network.

There are three steps to follow when configuring QoS using Cisco MQC configuration. Each step answers a question concerning the classes assigned to different traffic flows:

What traffic do we care about?

What will happen to the classified traffic?

Where will the policy apply?


Self Check

1. What is a class map?

2. How many class maps can be configured on a Cisco router?

3. What is a traffic policy?

4. What are the 3 basic elements of a traffic policy?

5. What command is used to assign a policy map to an interface?


Resources

Modular Quality of Service Command-Line Interface

http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps5014/products_feature_guide_book09186a0080088141.html

QoS Policing: Cisco Modular Quality of Service Command Line Interface

http://www.cisco.com/en/US/partner/tech/tk543/tk545/technologies_white_paper09186a0080123415.shtml






Implementing QoS with Cisco SDM


Objectives

Describe the features of the Cisco Security Device Manager (SDM).

Explain how SDM can be used to implement QoS on Cisco devices.

Compare and contrast four methods for configuring QoS on a network.


Cisco Security Device Manager (SDM)


Cisco SDM predefined categories

Real-time: Voice over IP (VoIP) traffic and voice-signaling traffic.

Business-critical: Business traffic important to a typical corporate environment.

Transactional (Citrix, SQLNet, Notes, LDAP, and Secure LDAP)

Management

Routing (egp, bgp, eigrp, and rip)

Best-effort: Remaining traffic.


Cisco SDM Graphic user interface


Steps 1 to 4: Creating a QoS Policy

1.

2.

3.

4.


Step 5: Launching the QoS Wizard


Step 6: Selecting the Interface


Step 7: Generating a QoS Policy


Reviewing the QoS Configuration


Completing the Configuration: Command Delivery Status


Monitoring QoS Status

1.

2.

A

B


Summary

Cisco Security Device Manager (SDM) is an intuitive, web-based device management tool that was created for easy and reliable deployment and management of Cisco IOS routers.

Cisco SDM simplifies and shortens the QoS deployment cycle. Cisco SDM helps in all of the five major aspects of successful QoS deployments.

Cisco SDM simplifies deployment and speeds provisioning of Quality of Service technology over a Cisco network infrastructure. It reduces human error and lowers training costs.


Self Check

1. What traffic classes are supported by SDM?

2. Which method of configuring QoS is the hardest to implement, requires the most time and offers the least modularity?


Q and A


Resources

Cisco AutoQoS Q&A

http://www.cisco.com/en/US/partner/tech/tk543/tk759/tk879/technologies_q_and_a_item0900aecd8020a589.shtml

SDM Demo Lab (Live Demo)

http://www.cisco.com/en/US/partner/products/sw/secursw/ps5318/prod_presentation0900aecd802adc65.html

Cisco SDM Multimedia Demo

http://www.cisco.com/cdc_content_elements/flash/sdm/sdm.exe

SDM Presentations (VoDs)

http://www.cisco.com/en/US/partner/products/sw/secursw/ps5318/prod_presentation_list.html

SDM Homepage

http://www.cisco.com/en/US/products/sw/secursw/ps5318/





http://www.cisco.com/cdc_content_elements/flash/sdm/sdm.exe



http://www.cisco.com/en/US/products/sw/secursw/ps5318/


Documents

Optimizing Converged Cisco Networks (ONT) · applications (hard QoS). Provides multiple service levels. RSVP is a signaling protocol to reserve resources for specified QoS parameters