QoS-Aware Service Composition for Converged Network–Cloud ...
Optimizing Converged Cisco Networks (ONT) · applications (hard QoS). Provides multiple service...
Transcript of Optimizing Converged Cisco Networks (ONT) · applications (hard QoS). Provides multiple service...
© 2006 Cisco Systems, Inc. All rights reserved.
Optimizing Converged Cisco Networks (ONT)
Module 3: Implementing IP QoS
© 2006 Cisco Systems, Inc. All rights reserved.
Selecting an Appropriate QoS Policy Model
© 2006 Cisco Systems, Inc. All rights reserved.
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.
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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.
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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
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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)
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IntServ Functions
Flow Identification Packet Scheduler
Data Plane
Routing Selection Admission Control
Reservation Setup
Control Plane
Reservation Table
Queuing & schedulingClassification & Policing
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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)
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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)
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RSVP Daemon
PolicyControl
AdmissionControl
Packet Classifier
PacketScheduler
Routing
RSVPDaemon
Reservation
Data
Simplex flow
Sender Receiver
?
OK
Path message
Reservation
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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
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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
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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
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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
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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?
© 2006 Cisco Systems, Inc. All rights reserved.
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.
© 2006 Cisco Systems, Inc. All rights reserved.
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
http://cisco.com/en/US/partner/tech/tk1330/tsd_technology_support_technical_reference_chapter09186a0080759886.html
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Using MQC for Implementing QoS
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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)
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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
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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
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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
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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.
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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
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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
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Modular QoS CLI Components
ACL, NBAR, DSCP, MPLS EXP BIT,
IEEE802.1p
to an interface or PVC (ATM, F.R.)
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Modular QoS CLI Example
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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.
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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
router(config-cmap)#
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)
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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
router(config-cmap)#
Extended ACL
Use an ACL as a match criterion
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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.
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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.
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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
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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
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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
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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
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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
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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])
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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])
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MQC Example
Voice traffic needs priority, low delay, and constant bandwidth.
Interactive traffic needs bandwidth and low delay.
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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
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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
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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?
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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?
© 2006 Cisco Systems, Inc. All rights reserved.
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
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Implementing QoS with Cisco SDM
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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.
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Cisco Security Device Manager (SDM)
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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.
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Cisco SDM Graphic user interface
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Steps 1 to 4: Creating a QoS Policy
1.
2.
3.
4.
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Step 5: Launching the QoS Wizard
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Step 6: Selecting the Interface
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Step 7: Generating a QoS Policy
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Reviewing the QoS Configuration
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Completing the Configuration: Command Delivery Status
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Monitoring QoS Status
1.
2.
A
B
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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.
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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?
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Q and A
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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/
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