QoS User view From modelling to service class

Transcription

1 QoS User view From modelling to service class STQ Workshop - 1 & 2 July 2009 P-Y Hebert AFUTT User Group vice-chairman ETSI All rights reserved

2 Index UMTS Classes of Service (CoS) ITU-T Y.1541 QoS classes ITU-T G.1010 QoS classes Per Hop Behaviour parameters (DIFFSERV) QoS classes (INTRADIFF) depending QoS parameters sensitivity 2

3 UMTS Classes of Service (CoS) (1/2) Conversational class Real time conversation - fundamental characteristics for QoS: preserve time relation (variation) between information entities of the stream; conversational pattern (stringent and low delay). Telephony speech (e.g. GSM), Voice over IP and video conferencing tools. Streaming class Real time streams - fundamental characteristics for QoS: preserve time relation (variation) between information entities of the stream. real time video (audio) Interactive class Interactive traffic - fundamental characteristics for QoS: request response pattern; preserve payload content. web browsing, data base retrieval, server access. Examples of machines interaction with remote equipment are: polling for measurement records and automatic data base enquiries (tele-machines). 3

4 UMTS Classes of Service (CoS) (2/2) Background class Background traffic - fundamental characteristics for QoS: the destination is not expecting the data within a certain time preserve payload content. preserve time relation (variation) between information entities of the stream; s, SMS, download of databases and reception of measurement records. 4

5 ITU-T Y.1541 QoS classes (1/2) 8 classes of services The characteristics of each Y.1541 QoS class are summarized here: Class 0: Real-time, highly interactive applications, sensitive to jitter. Mean delay upper bound is 100 ms, delay variation is less than 50 ms, and loss ratio is less than Application examples include VoIP, Video Teleconference. Class 1: Real-time, interactive applications, sensitive to jitter. Mean delay upper bound is 400 ms, delay variation is less than 50 ms, and loss ratio is less than Application examples include VoIP, Video Teleconference. Class 2: Highly interactive transaction data. Mean delay upper bound is 100 ms, delay variation is unspecified, and loss ratio is less than Application examples include signalling. Class 3: Interactive transaction data. Mean delay upper bound is 400 ms, delay variation is unspecified, and loss ratio is less than Application examples include signalling. Class 4: Low Loss Only applications. Mean delay upper bound is 1s, delay variation is unspecified, and loss ratio is less than Application examples include short transactions, bulk data, video streaming. Class 5: Unspecified applications with unspecified mean delay, delay variation, and loss ratio. Application examples include traditional applications of Default IP Networks. Class 6: Mean delay <= 100 ms, delay variation <= 50 ms, loss ratio <= Applications that are highly sensitive to loss, such as television transport, high-capacity TCP transfers, and TDM circuit emulation. Class 7: Mean delay <= 400 ms, delay variation <= 50 ms, loss ratio <= Applications that are highly sensitive to loss, such as television transport, high-capacity TCP transfers, and TDM circuit emulation. 5

6 Y.1541 IP QoS Class Definitions and Network Performance Objectives (2/2) QoS class IPTD IPDV IPLR IPER IPRR Applications (examples) ms 50 ms 1 x x ms 50 ms 1 x x ms U 1 x x Real-time, jitter sensitive, high interaction (VoIP, VTC) Real-time, jitter sensitive, Interactive Transaction data, highly interactive (Signalling) ms U 1 x x Transaction data, interactive 4 1 s U 1 x x Low loss only (short transaction, bulk data, video streaming) 5 U U U U - Traditional applications of default IP network 6 100ms 50 ms 1 x x x 10-6 loss/error (TV broadcast on High bit rate, strictly low IP) 7 400ms 50 ms 1 x x x 10-6 High bit rate, strictly low loss/error 6

7 ITU-T G.1010 QoS classes (1/2) Based on 3 key parameters impacting the user Delay Includes delays in the terminal, network, and any server. Delay variation Services that are highly intolerant of delay variation will usually take steps to at least significantly reduce the delay variation by means of buffering (although at the expense of adding additional fixed delay). Information loss Information loss is not limited to the effects of bit errors or packet loss during transmission, but also includes the effects of any degradation introduced by media coding for more efficient transmission (e.g. the use of low bit-rate speech codecs for voice). This results in 8 QoS classes defined according to the QoS criteria together and not separately This leads to some difficulties to take into account these QoS criteria properly 7

8 ITU-T G.1010 Applications vs delay & loss (2/2) Packet Loss 5% 0% Zero loss Conversational voice and video Voice/video messaging Streaming audio/video Delay 100 ms 1 s 10 s Fax 100 s Command /control (e.g. Telnet, Interactive games) Transactions (e.g. E-commerce, Web-browsing, access) Messaging, Downloads (e.g. FTP, still image) Background (e.g. Usenet) T

9 Per Hop Behaviour parameters (DIFFSERV) The Per Hop Behaviour parameters comprises three classes: AF: Assured Forwarding Comprises four independently forwarded AF classes, within each class one of three different levels of drop precedence can be specified. AFij represents the DSCP for AF class i with drop precedence j. It is recommended to support at least one AF class with two drop precedence levels. BE: Best Effort For BE traffic, packets are directed to a BE FIFO queue, but without any conditioning. They remain in the queue until layer 2 resources are made available, as a result of layer 2 on capacity control and scheduling. EF: Expedited Forwarding The EF PHB is designed to provide low-loss, low-latency, low-jitter, assured bandwidth services, where packets normally encounter short or empty queues. 9

10 From QoS criteria to QoS classes (INTRADIFF) (1/2) Class CoS1 CoS2 CoS3 CoS4 CoS5 Relative Sensitivity of QoS criteria Delay Fidelity Availability Capacity Queue supported Tolerant to moderate queuing Tolerant to moderate queuing Minimal queuing Minimal queuing Loss tolerant Loss tolerant Loss tolerant Cope with available bandwidth Cope with available bandwidth Variable bandwidth Variable bandwidth Min. guaranteed Fixed bandwidth CoS6 No queuing supported Loss tolerant Fixed bandwidth CoS7 To be defined to match the user needs 10

11 From modelisation (behaviour). to applications (2/2) Class Applications Behaviour with regard to the QoS criteria (Capacity, delay, fidelity, availability) Application examples CoS1 Flexible, asynchronous FTP, SMTP CoS2 Flexible, para-synchronous Web (http) CoS3 CoS4 CoS5 CoS6 Rigid, sporadic, para-synchronous, Sensitive to fidelity Rigid, sporadic, synchronous, Sensitive to fidelity and unavailability Rigid, non-sporadic, synchronous Rigid, non-sporadic, intolerant to loss Transactionnal Games Audio Streaming, Video Streaming Netmeeting (VoIP, Videophone) CoS7 Leased line emulation Teleworking 11

12 QoS criteria depending classes (INTRADIFF) Intradiff includes 96 sensibility levels (96 class possibilities): 4 (C) x 4 (D) x 3 (R) x 2 (A) sensibility levels 4 (Capacity) 4 (Delay). 3 (Fidelity). 2 (Availability) This allows for taking into account all the QoS requirement criteria. 12

13 Conclusion 3GPP has proposed a macroscopic classification based on the "Delay" (4 sensibility Level) criterion Y1541 has proposed 8 classes IUT-T G.1010 adds the tolerance to the losses (2 sensibility levels) as an additional criterion (8 class). DiffServ refines the tolerance to the losses (3 levels) criterion (14 classes possibilities). Intradiff allows for more refinements with : 4 (C) x 4 (D) x 3 (F) x 2 (A) sensibility criterion (96 class possibilities and +) to take into account all the behaviour / non functional aspects (QoS criteria). 13