Neal Seitz

Vice Chair, T1A1neal@its.bldrdoc.gov

Joint T1A1/T1S1 Meeting

October 2, 2002Ottawa, Ontario

QoS Signaling for IP-Based Multi-Service Networks:

Motivation, Requirements, and Proposed Actions

Adapted from material presented at the ATIS-sponsored Summit on Signaling for Voice over Internet Protocol, August 13-14, 2002

T1A1/2002-066

QoS Control: Key to Deployment of Multi-Service IP-Based Networks

Outline

• Context -- Importance of QoS Control

• Getting There -- Role of Y.1541 / Y.1221

• Example QoS Signaling Exchange

• Other Relevant International Standards Activities

• Proposed T1A1/T1S1 Standards Actions

Y.1541 QoS Classes and Y.1221 Traffic Contracts should be specified in IP QoS signaling protocols

Problem Context

Pr(e/o)mise of IP/PSTN Convergence• Cost savings through technology consolidation• Industry growth through service innovation

QoS Signaling: The Nexus and Gordian Knot• Convergence presupposes toll quality voice on a

multi-service, multi-provider IP infrastructure• Toll quality voice requires service differentiation

and resource control, QoS (and flow) signaling

Signaling QoS (and flow) parameters will be essential to successful IP/PSTN convergence

Importance of IP QoS Signaling

VoIP/MM needs are clear, but too demanding for today’s IP• Rec. G.114 -- End-to-end signal transmission time• Rec. G.109 -- Categories of speech transmission quality• Rec. G.107 -- Computation for transmission planning

IP QoS solutions exist, but are not widely implemented• RSVP/intserv -- Controlled load, guaranteed services• DIFFSERV -- EF, AF per hop behaviors (PHBs)• MPLS, GMPLS -- Traffic engineering, CoS, QoS, VPNs

IP QoS signaling is the practical means of relating user application needs with network QoS solutions

Rec. Y.1541: Quantifying User QoS Needs in IP Terms

Relate subjective descriptions of QoS imperfections …• Audio: “staticky, warbley, muffled, clipped”• Video: “blurry, jerky, blocky, busy, blotchy”

With measurable IP network/terminal characteristics …• Packet transfer delay, delay variation • Packet loss and error ratios

Capture results in a limited set of QoS classes … – Categorize the major IP user application needs

– Can be communicated among networks via signaling

– Can be implemented with existing IP QoS mechanisms

Terminal Terminal

NI to NI QoS (Y.1541) Speed, Accuracy, Dependability Service Availability (Future)

Y.1541 “Mapping” Function

Voice Video Data Call Control

Customer-Perceived QoS Subjective Descriptors Objective Estimators

Voice Video Data Call Control

Network QoSNetwork QoS Network QoS

ControlNetwork

ControlNetwork

BearerNetwork

BearerNetwork

BearerNetwork

ControlNetwork

NINI

Table 1/Y.1541 -- IP QoS Class Definitions and NP Objectives

NetworkPerformance

Parameter

Nature ofNetwork

PerformanceObjective Class 0 Class 1 Class 2 Class 3 Class 4

Class 5(Un-

specified)IPTD Upper bound

on the meanIPTD

100 ms 400 ms 100 ms 400 ms 1 s U

IPDV Upper boundon the 1-10-3

quantile ofIPTD minusthe minimum

IPTD

50 ms 50 ms U U U U

IPLR Upper boundon the packet

lossprobability

1*10-3 1*10-3 1*10-3 1*10-3 1*10-3 U

IPER Upper bound 1*10-4 U

Table 1/Y.1541 -- IP QoS Class Definitions and NP Objectives

NetworkPerformance

Parameter

Nature ofNetwork

PerformanceObjective Class 0 Class 1 Class 2 Class 3 Class 4

Class 5(Un-

specified)IPTD Upper bound

on the meanIPTD

100 ms 400 ms 100 ms 400 ms 1 s U

IPDV Upper boundon the 1-10-3

quantile ofIPTD minusthe minimum

IPTD

50 ms 50 ms U U U U

IPLR Upper boundon the packet

lossprobability

1*10-3 1*10-3 1*10-3 1*10-3 1*10-3 U

IPER Upper bound 1*10-4 U

Table 1/Y.1541 -- IP QoS Class Definitions and NP Objectives

NetworkPerformance

Parameter

Nature ofNetwork

PerformanceObjective Class 0 Class 1 Class 2 Class 3 Class 4

Class 5(Un-

specified)IPTD Upper bound

on the meanIPTD

100 ms 400 ms 100 ms 400 ms 1 s U

IPDV Upper boundon the 1-10-3

quantile ofIPTD minusthe minimum

IPTD

50 ms 50 ms U U U U

IPLR Upper boundon the packet

lossprobability

1*10-3 1*10-3 1*10-3 1*10-3 1*10-3 U

IPER Upper bound 1*10-4 U

Table 2/Y.1541Guidance for IP QoS Classes

QoSClass

Applications (Examples) Node Mechanisms Network Techniques

0Real-Time, Jitter Sensitive,High Interaction(VoIP, VTC)

Constrained Routing andDistance

1Real-Time, Jitter Sensitive,Interactive (VoIP, VTC)

Separate Queue withPreferential Servicing,Traffic Grooming Less Constrained Routing

and Distance

2Transaction Data, HighlyInteractive (Signalling)

Constratined Routing andDistance

3Transaction Data,Interactive

Separate Queue,Drop Priority Less Constratinged

Routing and Distance

4Low Loss Only (ShortTransactions, Bulk Data,Video Streaming)

Long Queue,Drop Priority

Any Route/Path

5Traditional Applications ofDefault IP Networks

Separate Queue(Lowest Priority)

Any Route/Path

Attributes of the Y.1541 IP Network QoS Classes

• Encompass the major IP user application categories• Are relatable to practical IP network QoS mechanisms• Can be achieved in realistic network implementations• Are verifiable at jurisdictional network boundaries

(TE/IWF can measure QoS to ensure values are met)

• Can support QoS negotiation among networks

Meet the need for a lingua franca to support QoS interworking

Y.1221: Traffic and Congestion Control in IP Based Networks

Y.1221 Traffic Contract complements Y.1541 QoS Class by describing flow characteristics and limits

Traffic Contract

• Dedicated BW• Statistical BW• Best Effort

• Max Pkt Size• Token Bucket

–Rate (Rp, Rs)–Size (Bp, Bs)

(Y.1541)

IP Transfer Capability Traffic DescriptorQoS Class

Signaling QoS and Flow Requests:Requirements Proposed by SG 13

• Allow the user requesting service to specify QoS class• Allow specification of traffic descriptor (Rec. Y.1221)• Allow well-defined apps to be identified ex(im)plicitly• Support requests for basic IP transport: QoS, traffic• Let user decide whether to take lower QoS or clear call• Implement dynamic QoS control, not static allocation• Support QoS class mapping among diverse networks• Allow QoS choices for call control, availability (future)

Signal Y.1541, Y.1221 QoS / flow values explicitly

Terminal Terminal

Example QoS Signaling Exchange

Customer Service Request, Including Call Characteristics

ControlNetwork

ControlNetwork

BearerNetwork

BearerNetwork

BearerNetwork

ControlNetwork

Customer Service Notification, Including Call Characteristics

Signaling Message(with QoS/Flow RQ)

Translation of Service RQ to Y.1541/Y.1221 QoS/Flow RQ

Translation of Y.1541/Y.1221 QoS/Flow RQ to Service RQ

Terminal Terminal

Example QoS Signaling Exchange

Customer Service Confirmation, Including Call Characteristics

ControlNetwork

ControlNetwork

BearerNetwork

BearerNetwork

BearerNetwork

ControlNetwork

Service Response, Possibly Including New Call Characteristics

Translation of Y.1541/Y.1221 QoS/Flow RSP to Service RSP

Translation of Service RSP to Y.1541/Y.1221 QoS/Flow RSP

Signaling Message(with QoS/Flow RSP)

Terminal Terminal

QoS Signaling Completed-- Flow Established

ControlNetwork

ControlNetwork

BearerNetwork

BearerNetwork

BearerNetwork

ControlNetwork

Customer Data Customer Data

(QoS and flow characteristics consistent with Y.1541, Y.1221)

Other Relevant Activities: IETF IPPM

Topic ITU-T Recs IETF RFCs

Framework I.350, Y.1540 2330

Loss Y.1540 2680

Delay Y.1540 2679 (One Way)

2681 (Round Trip)

Delay Var. Y.1540 (I-D on IPDV)

Availability Y.1540 2678

Sampling Y.1540 (Availability) 2330

(I-D on Periodic Streams)

Other Relevant Activities: ETSI TS 101-329-2

TIPHON Speech QoS Classes

• Wideband -- “Better than PSTN”• Narrowband -- “Similar to PSTN”

– High, Medium, Acceptable

• Best Effort -- “No guarantees of performance”

Limitations -- Applicable Only to IP Telephony• Do not address data, video, multimedia IP applications• Do not support requests for basic IP packet transport

TIPHON classes alone are insufficient to signal user QoS requirements in multi-service IP based networks

Call Signalling

Packet FlowQoS Signalling

Application Plane

Transport Plane

Other Relevant Activities: SG 16 (H.qos.arch)

Service Domain 1

Transport Domain 1

Transport Domain 2

Transport Domain 3

Service Domain 1

Application Level QoS Signalling

H.323 Annex N

Vertical QoS Signalling

(H.trans.cont)

Transport Level QoS Signalling

(H.trans.cont or NSIS)

H.323 Annex N

H.323 Annex N

Adapted From: IP Cablecom & MEDIACOM 2004 Workshop, 12 - 15 March 2002 Geneva

Liaison from SG 11 to SGs 12 and 13 on Generic End-to-End QoS Service Requirements

(March, 2002)

• “We would like to receive guidance from SG 12 what set of QoS service classes should be used. Based on ITU-T Recommendation G.1010 and the intentions of SG16 for H.mmclass we assume the ETSI TIPHON defined speech QoS service classes for VoIP.”

• “We would like to receive guidance from SG 13 to which specific QoS classes in IP and ATM the QoS services classes in BICC networks (and potentially other networks like SIP and H.323) need to be mapped for the existing PSTN/ISDN/PLMN services.”

T1A1/T1S1 should address these issues, develop U.S. views/proposals for input to SGs 12, 13, and 11

SG 11 Proposed Framework for End-to-End QoS Service Control and Network QoS Control

1) BICC, SIP, H.323 CSF CSF

BIWF BIWF

IP network

supporting

IPQoS/IPTC

2) CBC, H.248/MEGACO

3) IP BCP

(SG13) IPQoS/IPTC

(SG13) IPQoS/IPTC (SG13) IPQoS/IPTC

(TIPHON) (TIPHON) (TIPHON) End-to-end QoS service control

End-to-end QoS service control

End-to-end QoS service control

(TIPHON) QoS service control

(TIPHON) QoS service control

2) CBC, H.248/MEGACO

4) DiffServ, RSVP, MPLS 4) DiffServ, RSVP, MPLS

SG 11 should address all IP applications (not just voice) in defining QoS service control protocols

Business Realities and Standards Impacts

Feedback from the VoIP Summit• IP does not prove in end to end as a replacement for the

PSTN in providing voice telephone service• The payoff is in combining voice with data, video, and

other applications in a multi-service IP network

QoS Signaling Implications• Signaling QoS classes that address only VoIP will not

be fruitful, and should not be recommended by ITU-T• Comprehensive, multi-service QoS values must be

specified in IP network QoS signaling protocols

T1A1/T1S1 should recommend Y.1541/Y.1221 to ITU-T as basis for IP network QoS signaling

Upcoming ITU-T Meetings, Proposed Actions

SG 13 (Nov. 2002): Address SG 11 Liaison Response Existing TIPHON voice QoS classes do not provide an adequate

basis for multi-service IP network QoS specification

SG 12 (January 2003): Address SG 11 Liaison Response– Y.1541/Y.1221 values (plus codec specifications) should be

defined in SG 11 defined IP network QoS signaling protocols

SG 11 (Nov. 2002): Define QoS Signaling Requirements– Architecture, QoS request attributes, signaling flows, examples– Reference Y.1541/Y.1221 to define signalling message content

Coordinated effort among ITU-T SGs warranted

Backup Slides

ETSI TR 101-329-2

  

3(WIDEBAND)

2 (NARROWBAND) 1(BEST

EFFORT) 2H

(HIGH)2M

(MEDIUM)2A

(ACCEPTABLE)

Overall Transmission

Quality Rating (R)

(see note 2)> 80 > 70 > 50 > 50

(see note 3)

NOTE 1: The R-value incorporates all degradations, including the effects of packet loss.NOTE 2: The R-value characterization of systems employing wideband codecs is under study.NOTE 3: The rating for the best effort class is a target value.

Table 1: Overall transmission quality Rating (R) for TIPHON systems

(Overall transmission quality rating (R) describes the full acoustic-to-acoustic (mouth to ear) quality, experienced by an average user, for a typical situation using a "standard" telephony handset.)

ETSI TR 101-329-2

Overall Transmission

Quality Rating

90 < R < 100 80 < R < 90 70 < R < 80 60 < R < 70 50 < R < 60

User's Satisfaction

Very satisfied Satisfied Some users dissatisfied

Many users dissatisfied

Nearly all users

dissatisfied

Table 2: Categories of speech transmission quality as defined in ITU-T

(The relation between overall transmission quality rating (R) and user perception of quality is defined in ITU-T Recommendation G.109. Table 2 is extracted from that recommendation.)

ETSI TR 101-329-2

 

3(WIDEBAND)

2 (NARROWBAND) 1(BEST

EFFORT)2H

(HIGH)2M

(MEDIUM)2A

(ACCEPTABLE)

Relative Speech Quality

(one way, non interactive speech quality)

Better thanG.711 [6]

 

Equivalent orbetter than

ITU-TRecommendation

G.726 at 32 kbit/s [7]

Equivalentor better

than GSM-FR

[1]

Not defined Not defined

Resultant Overall

Transmission Quality Rating

(R)

n.a. > 86 > 73 > 50 > 50

NOTE 1: The R values above are derived from E-Model calculations assuming that perfect echo control is deployed, that there is zero delay through the system, that standard terminals are used, also that all impairments related to low bit-rate coding - including the effects of packet loss - are taken into account.NOTE 2: "Relative speech quality" does not describe the Listener Speech Quality (the full acoustic-to-acoustic (mouth to ear) quality that will be experienced by a user). This will be dependent on the acoustic quality of the individual TIPHON terminal as well as the quality of the TIPHON network.NOTE: The use of codec examples indicates a relative speech quality, not a recommended codec for implementation. The performance levels include any degradation caused by network or terminal, such as packet loss.

Table 3: Listener speech quality of TIPHON systems

ETSI TR 101-329-2

    3

(WIDEBAND)

 

2 (NARROWBAND) 

  1

(BEST EFFORT)

 2H

(HIGH)

 2M

(MEDIUM)

 2A

(ACCEPTABLE)

End-to-end Delay

< 100 ms < 100 ms < 150 ms < 400 ms < 400 ms

NOTE: The delay for best effort class is a target value.

Table 4: End-to-end delay for TIPHON Systems

Specification of QoS Parameters -- Ongoing and Planned Work

IPPM• RFCs Planned

– Loss Patterns

– Bulk Transfer Capacity

• I-Ds Received – Packet Reordering

– Msmt Protocol Rqmts

– MIB

• Newly Chartered Work– Link BW Capacity

WP 4/13• Y.1540 Enhancements

– IPDV Definition(s)

– Bursty Packet Loss

– Service Availability

• Y.1541 Enhancements– BC Quality Video QoS?

• Signaling Requirements• Y.1530 (Call Processing)• “Other” (e.g., MPLS, …)