aims workshop heidelberg, 9-11 march 1998 piet van mieghem basic functionality of quality of service...

AIMS WorkshopHeidelberg, 9-11 March 1998 Piet Van Mieghem

Basic Functionality of

Quality of Service in

Multimedia Networks

Piet Van Mieghem


Outline

Introduction

Multimedia

QoS market trends

Packet networks & statistical multiplexing

QoS : What?

Basic Network functionality required

Conclusions


Outline

Introduction

QoS : What?

Conclusions


Evolution

Advances in Micro-electronicsAdvances in Micro-electronics

Fast computersFast computers

MultimediaMultimedia

Data WorldData Worldnon-real timenon-real time

Telecom WorldTelecom Worldreal-timereal-time

best of both worlds

High speed networksHigh speed networks


Multimedia Marketing Trends

Even if a minority asks for QoS, the network provider is forced to invest in QoS to maintain (or enlarge) its market share

QoS provisioning linked to pricing will be a competitive weapon in future telecommunications networks

MULTIMEDIADiscovery of

Internet(Connectivity)

Attractionto Internet

(Simplicity)

Used to Internet

Frustration withlow QoS

inherent in best effort

Willing to pay for QoS

guarantees

ubiquitousguaranteed qualitylow costBusiness

on Internet

TODAY


Customer Centric Evolution

QoS Complexity

QoS granularity

BE prioritised BE

impact ofguaranteed

QoS

CoSCustomer fine-tuned QoS

Time

flat fee detailed invoice

end system

networkcentric

CL

CO


Stochastic Nature of Information

Prob[x< S< x+dx]

S(t)

t

x correlation depth k

k

R(k) = E[S(t+k)S(t)]

E[S]

max(S)

burst size

PCR

SCR

MBS


Statistical Multiplexing

4

3

2

1

0120100806040200

time (ms)

4

3

2

1

0120100806040200

time (ms)

bandwidth (Mb/s) bandwidth (Mb/s)

No statistical multiplexing PCR = 4 Mb/s

Statistical multiplexingmin. capacity: 3.4 Mb/s


Outline

Introduction

QoS : What?

Conclusions


QOS: definition

Application layer: Grade of Service (GOS) hard to define precisely (perceived quality, human appraisal)

alternative definition: GoS is related to blocking/failures

Transport layer: QoS routing (end-to-end) path through network subject to QoS requirements

Network layer : Quality of Service (QoS)

a measure (a ratio, a maximum, an average/variance/ quantile of a probability distribution,...) acting on a property (a loss, a delay, a cost, ...) of a cell/packet flow


QoS Associations

QoS is related to RESOURCES in the network

states in the network, basically CO in practice

end systems cannot control network resources

driver to a network centric view

current Internet

opportunity for network operators and network manufacturers

Control of QoS (i.e. control of resources) is key

resources = assets = money/capital

QoS control implies OPTIMALITY, because suboptimal control simply means loss of revenue

importance of Admission Control


Basic Network Functionality for QoS provisioning

Functionality

real-time notion

multiparameter routing

signalling

traffic managementadmission controlinput controlfailure controlqueue controlpriority control

ATM IP

AAL1

PNNI

PNNI/BISUP

ATC’svendor specificGCRAvendor specificintelligent schedulingPOB,PBS,HOL,EPD,..

RTP

QoSR (still empty)

RSVP (partly)

Integrated Services(current efforts)


QoS Routing

QoS Routing = Multiple parameter routing subject to constraints

Link metrics are vectors

NP-complete good heuristics needed

Policy Routing is related to QoS routing

Routing with partial information

A

B C D

EF G

H

IJ

K

delay: 10 msbandwidth :100 Mb/scell loss ratio: 1.0e-6administrative weight: 4


Signalling

ATM Network

setupsetup

setupcall

proceedingcall

proceedingconnect

connectconnect

connect ack connect ack

connect ack

setup time

Functionality that transports control information for installing resources along the path of each individual flow (or connection)

consequence of CO-mode

* Complex protocols* Limited number of connections


Traffic Management

Final (nodal) decision on installing resources:

admission function (CAC)

CAC is inherently difficult

Need for input control

never trust the user

check the contracted traffic parameters

Congestion functionality

Various ATM bearer capabilities (DBR, SBR, UBR, ABR, GFR, ...) or Internet services (guaranteed service, controlled load, BE)


Outline

Introduction

QoS : What?

Conclusions


QoS : Summary

Multimedia will evolve to QoS-awareness and eventually to QoS guarantees

No smooth evolution from BE to guaranteed QoS provisioningQoS complexity sky-rockets due to guarantees

QoS is complex and requires additional network functionality

QoS is linked to revenue (money) via network resourcesQoS is associated with optimality

Optimal QoS Control needs stochastic analysisStill a long way to go

aims workshop heidelberg, 9-11 march 1998 piet van mieghem basic functionality of quality of service...

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