Policy-based QoS Framework for Policy-based QoS Framework for

Multi-service IP NetworksMulti-service IP NetworksHoon Lee

E-mail: hoony@changwon.ac.kr

Network and Service Assurance Lab.Dept. of Information & Communications

Engineering Changwon National University

Changwon, Korea

Service Trends:Service Trends:Triple Play=Triple Play=VoiceVoice++DataData+Video+Video

There exists no killer applications! Pack them up!!

Voice from Phone

Data from PC

VoD/ TVVideophone

Triple Play Services:

- Italy: FastWeb

- Japan: NTT RENA, KDDI, SoftBank

- Korea 1. KT: All up prime (Megapass+VoIP+Videophone+Messaging+Broadcasting)

2. Dacom: Internet+VoIP+ Broadcasting

3. Hanaro Telecom: 2 Scenarios

PSTN: xDSL+POTS+SkyLife

Cable: Cable internet+VoIP+Broadcasting

Technologies for Internet QoSTechnologies for Internet QoS

Speed up & Over-provisioning (QoS-Free) - Current BE service - Applicable to any kind of future applications * Almost zero delay if link speed is in the order of 10s of Mbps

Service Differentiation for Priority Traffic SP, CBQ, Hybrid - Wired network: IETF DiffServ + MPLS (Priority service +Tunneling) Priority: EF > AF > BE - Wireless ad hoc network: SWAN (Feedback control + CAC) Priority: rt traffic > BE traffic Policy-based QoS Guarantee - Policies for service differentiation / BW allocation / scheduling / routing

Policy-based QoS Framework of TEQUILAPolicy-based QoS Framework of TEQUILA

Static policy

(Long-term)

Dynamic policy

(Short-term)

Policy Management Tool

Policy server

Policy consumer

SLS Subscr.

SLS Inv.

Traffic Estimation

Network monitoring

Network Provisioning

Resource manag.

Route manag

SLS Management Performance Manag. Traffic Engineering

Policy management

SLS

Req.

From

Customer

NTT NTT RENARENA’s’s QoS FrameworkQoS Framework

RENATM: Resilient Network Architecture

SCS: Session control server

BB: Bandwidth broker

PS: Policy-server

NIB:Network information base

BB

Video server

Web server

PC

Phone

Phone

PSTNPC

SCS

NIBService/Network Control Platform

Separation of control and data transfer plane

Flexible network control

Centralized QoS management e2e QoS

From NMS

PS

e2e Optical network

Policies for IP QoSPolicies for IP QoS

Principle for IP QoS: Be faithful to IP’s philosophy.

- Advantage of IP: Connectionless paradigm

Simple & scalable

IP QoS Provisioning: via Policy-based networking

- Destination-based routing based on OSPF principle

- Treat QoS traffic with higher priority than the BE traffic

SP does not sacrifice the lower class traffic

when the link speed exceeds 10s of Mbps!!

- Protection of QoS traffic: Class-based CAC

- Network–wide: Interoperation of Policy Server/NMS

Dynamic CAC & bandwidth management

Policy-based Networking: Big PicturePolicy-based Networking: Big Picture

Core node: DiffServ-based CBQ + PHB-based Scheduling + MPLS-TE

Edge node: SLA negotiation, UPC, Packet classification / QoS mapping, CBQ, Packet-scheduling

Voice buffer

PBX VoIPG/W

Phones

AccessRouter

BandwidthBroker

VoiceData

VPN

Core Rout

er

Access network

PCs/Phones/TEs/Servers

MPLS Tunnel

Premium backbone network

AN Route

r

QoS Server

(SLA)

PCs/Servers

…

Policy Base

Traffic meterNIB

Best effort IP network

Policy server farm

Current

Packet Level SLSPacket Level SLS

Service type

Attributes Application services

QoS Requirements(ITU-T)

Data servic

e

Conventional BE service

Email, ftp, low

quality video

None

Voice servic

e

QoS compatible to PSTN

Internet telephony,Interactiv

e multimedia

E2E delay < 150ms for 99.99% of

packets,PLR < 10-3

Video servic

e

NewTV,

Videoconferencing

E2E delay < 150ms for 99.99% of

packets,PLR < 10-4

Bundle servic

e

InteractiveIP

VPN ,www, on-line game,

streaming multimedia

Minimum contracted BW,

E2E delay < 1~4secPLR < 10-6

Mapping between DiffServ & MPLSMapping between DiffServ & MPLSQoS

Services Premium

serviceAssuredservice

Better than BE service

Best-Effort service

DiffServPHB

EF AF 1/2 AF 3/4 BE

MPLSLabel

Platinum Gold Silver/ Bronze Steel

ITU-T QoS Class

0/1 2 3~4 5

Typical Applications

VoIPVPN

Signaling,VoD

WWW, telnet,

streaming service

e-mail

Bandwidth Allocation AlternativesBandwidth Allocation Alternatives

Bandwidth reservation model

- Absolute QoS guarantee

- Low efficiency

- e.g.: IntServ architecture

- Application to: Videophone service

Bandwidth share with priority scheme model

- Statistical QoS guarantee

- High utilization

- e.g.: DiffServ architecture

- Application to: Multi-service

Bandwidth Reservation Model : Bandwidth Reservation Model : Videophone Service ArchitectureVideophone Service Architecture

Cv=C

C: Number of videophone connection (channel)

: Bandwidth of a videophone connection

E-S/W

Video Phone

Router

LAN

IP Network(DiffServ)

Cv = ?

Internet traffic

Cd

…

…

ISP

E-S/W

Input to The SystemInput to The System

Parameters: Number of subscribers: M (Tens of thousand) Fraction of active connections at busy hour: (10%~20%) Mean session duration: 1/ ( 1,000seconds) Mean session arrival rate: (0.01 ~ 1 ) Session broking probability: (0.5~1%) Bandwidth requirement of a Videophone session:

= 2Mbps (For basic rate service)

(8bits/pixel250200pixels/frame5frames/sec=2Mbps)

Analytic System ModelAnalytic System ModelAssumption on the session:Session arrival: Poisson arrivalSession duration: Exponential distribution

System model:Infinite number of traffic sourcesFull availability linkM/M/c/c Queuing model with C concurrent channels

Erlang B-formula for GoS of videophone service

Constraint on the Service level: E(C,) .

where = (M /)/3600

.

!

!),(

0

C

i

i

C

i

CCE

Results and DiscussionResults and DiscussionTypical Assumptions:M = 30,000 residential subscribers = 0.1 (Residential= 10%, Business=20%)1/ =1,000 seconds =0.36/0.72 sessions / Busy hour / Person (Residential / Business) =1% = 2Mbps (basic rate)

Result of computation:

Input traffic in Erlang: 300 Erlang

Computed number of channel: 323 Channels

Required bandwidth: Cv=C = 323 2Mbps = 646Mbps

To provide the safety margin, we have to take into account the

traffic from alternate route of the neighboring nodes:

Cv Final= 2 Cv=1.3Gbps Final result.

ComparisonComparison: : Residential vs. BusinessResidential vs. BusinessWhen the subscribers are business customers

- = 0.2

- = 0.72

(The offered load increases to 4 times that of the residential subscribers!)

Total required bandwidth for a number of subscribers:Number of subscriber

Required number of channel

(residential / business)

Total Required Bandwidth

(residential / business)

30,000 323 / 1292 1.3 / 5.2 Gbps

60,000 650 / 2600 2.6 / 10.4 Gbps

90,000 928 / 3712 3.7 / 14.8 Gbps

Bandwidth Share Model : Bandwidth Share Model : Strict Priority Scheduling SchemeStrict Priority Scheduling Scheme

System model: DiffServ-aware MPLS

Service model: Strict priority (SP) to voice over data1 over data2

Router model: M/G/1 queue with non-preemptive service

Objectives: Evaluation of delay for class1, 2, and 3 packets

Our concern:

1. Can we apply the SPSS in a DiffServ router for BcN?

2. How about the behavior of delay with respect to the system parameters?

Voice packet

Data1 packet

SP

C

Data 2packet

System ModelSystem Model

System parameters:

- Mean arrival rate for voice/data1/data2: 1, 2 , 3

- Mean service time for voice/data1/data2 : 1/1, 1/2 , 1/3

- Second moment of service time: E[k2],k=1,2,3

- Offered load for voice/data1/data2 : 1, 2, 3

- Link capacity: C

Source models:

- Voice: Poisson arrival, fixed packet size

- Data1 & data2: Poisson arrivals, Pareto distributions

Delay PerformanceDelay Performance

Mean waiting times for M/G/1 queue with SP service:

)1(2

][

1

3

1

2

1

k kkE

W

,)1)(1( 211

2

RW

,)1)(1( 32121

3

RW

Mean waiting time for M/G/1 queue with FIFO service:

).2

1

1(1 22

SFIFO

CW

R

CS2=squared coefficient of variation for

service time of a packet

Numerical ExperimentsNumerical Experiments

Source traffic profile:

- Voice source: G.711 Voice coder, 216bytes

- Data source: Ethernet frame, Pareto distribution,

Minimum packet size, m: 500~1500bytes

Tail index: =3

Link capacity per output port: 1M, 10M, 100Mbps

).0,(,)(1}Pr{)( mll

mlLlF

Traffic Load TypeTraffic Load Type

Load Type

1 2 3

A 0.1 0.4 0.4 0.9

B 0.3 0.3 0.3 0.9

C 0.5 0.2 0.2 0.9

D 0.7 0.1 0.1 0.9

Light-voice

Heavy-data

Heavy-voice

Light-data

Waiting Time of Voice Packets for Waiting Time of Voice Packets for Different Link CapacitiesDifferent Link Capacities

m2=500bytes, m3=1500bytes

Under SP scheduling scheme, delay of voice packet is

almost negligible for high-speed links!

Waiting Time of Voice Packets for Waiting Time of Voice Packets for Different Service SchemesDifferent Service Schemes

The conventional wisdom of

“SP isolates voice traffic from non- voice traffic”

does not hold!

This is more evident for the WFQ-families.

m2=m3=1,000 bytes, C=1Mbps

Delay Performance of Data TrafficDelay Performance of Data Traffic Performance comparison between different classes:

.

1

1

211

2

W

W.)1(

1

321

1

2

3

W

W

1=0.2

1=0.4

2=0.2

2=0.4

1=0.2

SummarySummary

Policy is important for QoS provisioning in future Internet.

Network provisioning is dependent on the policy.

Reservation model over-estimates the network resources.

Shared bandwidth model will prevail.

Accurate dimensioning of network resources saves cost.

ReferencesReferences[Lee] Hoon Lee, “Strategies for the construction of Policy-based

managed IP QoS”, Final Report of NCA II-RER-04041,

November 30, 2004.

[Lee] Hoon Lee et al., “Dimensioning NGN for QoS guaranteed voice

services”, Jr. of IEEK, Vol. TC-40, No.12, December 2003.

[Lee] Hoon Lee, “Delay analysis of DiffServ/MPLS network”,

Industrial Mathematics Initiative 2004, August 26-28, Korea.

[Lee] Hoon Lee et al., “Delay performance of non-real-

time services for the strict priority scheduling scheme”, Jr. of

the research institute of industrial technology, Vol.18, May 2004.

[Trimintzios] P. Trimintzios et al., An architectural framework for

providing QoS in IP differentiated services networks, TEQUILA

Project report.