QoS in IP Networks: an industrial viewpoint

Transcription

1 International Workshop on: QoS in Multiservice IP Networks QoS in IP Networks: an industrial viewpoint Sergio R. Treves Alcatel Rome, January 2001

2 Summary Network model Parameters and requirements for QoS Reference network configurations for End-to-End QoS Main QoS techniques and network architectures Conclusions -1-

3 Network Model -2-

4 Net-Economy Business model CPE Access Edge Core Retail Wholesale Retail Wholesale Consumer Enterprise SoHo SME Corporate GSM GPRS EDGE UMTS Cable Satellite WDM ADSL VDSL LMDS PON NB W ireline xdsl TDM Mobile Service Providers (MSPs) Competitive Access Providers (CAPs) Internet Service Provider s (ISPs) Established Service Providers (ESPs) Application Service Providers (ASPs) Backbone Service Providers (BSPs) IP/ MPLS DWDM QoS MultiMedia Broadband Value Added Applications Cost / Bandwidth -3-

5 Next Generation Network model Legacy Network Signalling/Service Legacy Network Media Sign. Gway Call Server Services Network Independent Services Gateways -4-

6 Communication Scenarios PSTN IP PSTN PC to PC PC to Gateway Gateway to Gateway -5-

7 Parameters and Requirements for QoS -6-

8 Quality of Service (QoS) Quantative measure of the degree of satisfaction perceived by an end user (customer) of a service, expressed by means of QoS parameters that can be measured including: availability error performance response time lost calls due to network congestion Service Providers may guarantee a particular level of QoS to their customers by means of a Service Level Agreement (SLA) -7-

9 Quality of Service Aspects Network Performance aspect Traffic performance: throughtput, delay & jitter, loss Error performance Dependability: availability, reliability, maintainability End-User aspect Service retainability (provision for a requested duration) Service integrity (provision without excessive impairments) Service accessibility (when requested) -8-

10 Layer-specific QoS for Voice Application layer Telephony service = two-way transport of voice signals at a desidered quality R IP Network layer Ingress point Transport service = one-way transport of voice packets Egress point Encoding FEC Packetization Dejittering Decoding -9-

11 Relevant QoS Parameters IP Network Layer Ingress-to-Egress delay Ingress-to-Egress jitter Ingress-to-Egress packet loss Application Layer Mouth-to-Ear delay Distorsion of the voice signal - encoding/decoding - packetisation delay - dejittering loss due to: -10-

12 UMTS QoS Classes defined by 3GPP (standards TS ) Characteristics Traffic type Transfer Delay requirement Transfer Delay Variation (Jitter) Low bit error rate Guaranteed bit rate Typical applications Real-Time Conversational stringent stringent no Yes (CBR, VBR) VoIP, Video-conferencing Audio-conferencing Real-Time Streaming constrained constrained no Yes (VBR) Broadcast services (audio, video), News, Sports Non Real-Time Interactive no no yes No (VBR) W EB browsing, Interactive Chat, Games, m-commerce Non Real-Time Background no no yes No (ABR) , SMS, database downloads -11-

13 QoS Classes defined by ETSI TIPHON Parameter Class Class 4: Best (better than toady s PSTN/ISDN) Class 3: High (equivalent to today s PSTN/ISDN) Class 2: Medium (equivalent to today s wireless networks) Class 1: Low (significantly impaired, but usable) Overall Speech Transmission Quality Rating (R) G R< R<90 70 R<80 60 R<70 End-to-End Delay (ms) < 100 < 100 < 150 < 400 Listening Speech Quality (one way, non conversational) Better than G.711 Equivalent or better than G.726 at 32 kb/s Equivalent or better than GSM-FR Undefined TIPHON= Telecommunication Internet P rotocol H armonization O ver N etworks -12-

14 Reference Network Configurations for E2E QoS -13-

15 Current Generation Network Internet Backbone and other Carrier Backbones BSP ISP/IAP ESP/MSP CAP/ISP data Packet Network POP POP data Network Peering data Packet Network POP POP voice data BB Access Network ADSL HFC voice POTS BA, PRA Switched Circuit Network (SCN) POTS BA, PRA GSM GPRS UMTS ESP/MSP Switched Circuit Network (SCN) GSM GPRS UMTS POTS BA, PRA BB Access Network POTS BA, PRA ADSL HFC Corporate and Residential CPE Corporate and Residential CPE -14-

16 Next Generation Network (NGN): generic reference configuration T x Packet Network (PN x) W x Access Network (AN x) W x xz Operator x Switched Circuit Network (SCN x) Packet Network (PN z) xy Operator y Switched Circuit Network (SCN y) T* x T* U* x U* x x yz Operator z Packet Network (PN y) W y V y Access Network (AN y) T y NT CPN U x TE Customer Premises (CP x) Customer Premises (CP y) U y TE CPN NT -15-

17 New Generation Networks: Reference Configurations t x u x AN x v x PN x xz PN z yz PN y v y AN x t y u y t x u x SCN x w x PN x xz PN z yz PN y w y SCN y t y u y t x u x AN x v x PN x xz PN z yz PN y w y SCN y t y u y t x u x AN x v x PN x xy PN y v y AN y t y u y t x u x SCN x w x PN x xy PN y w y SCN y t y u y t x u x AN x v x PN x xy PN y w y SCN y t y u y PN= Packet Network (IP, ATM, MPLS) AN= Access Network (ADSL, HFC, PON+VDSL, LMDS, UTRAN) SCN= Switched Circuit Network (PSTN, ISDN, PLMN) x, y, z= Different operators -16-

18 Main QoS Techniques -17-

19 QoS Architectures Single IP transport provider (1) Intserv IP Control of IP network QoS parameters Feasibility of Intserv E2E Dimensoning of pre-provisioned Trunks -18-

20 QoS Architectures Single IP transport provider (2) Diffserv IP E2E Diffserv -19-

21 QoS Architectures Single IP transport provider (3) Intserv IP Diffserv Intserv in the access/edge and Diffserv in the core -20-

22 QoS Architectures Multiple IP transport providers IP Connection path crossing multiple transport providers Interworking of multiple combinations of QoS control architectures -21-

23 IntServ vs DiffServ Techniques Network Technique Features Adavantages Disadvantages IntServ - Standardized E2E signalling protocol (RSVP) - Requested services offered (CL and GS) - RSVP not scalable and complex due to need for core routers to maintain control state for each flow - Common agreeemnt among all ISP s needed for E2Econnections (on RSVP use) - Not suitable for E2E QoS DiffServ - Scalable (focusing on traffic aggregates with similar service requirements) - Requested services offered - No signalling protocol to check the availability of resources E2E - Not suitable for E2E QoS IntServ in the access & DiffServ in the core - Scalable (DiffServ) - Standardized IntServ/RSVP signalling protocol for inter-domain - Common agreement needed between ISP s on the use of IntServ/RSVP for inter-domain signalling -22-

24 IntServ mapped on DiffServ Sender A DiffServ access network IntServ ER1 BR1 backbone network BR2 Intserv mapping on Diffserv ER2 access network IntServ Receiver Y -23-

25 Fixed pipes mapping IntServ on DiffServ BR1 BR2 Intserv flows leave the IP backbone though border router BR2 BR4 Intserv flows enter the IP backbone through border router BR4: 1) performs the Intserv processing 2) checks if there are sufficient amount of resources available in the IP backbone. If the flow is accepted, then all packets are sent to BR2 BR3 Statically configured pipes with a certain amount of bandwidth from each ingress router towards each egress router: * MPLS with E-LSPs or L-LSPs * ATM PVCs -24-

26 E2E QoS A generic Communication Scenario (1) Intserv/RSVP (inter-domain signaling) ATM Diffserv 1 Diffserv 2 Intserv Diffserv 1 = fixed pipes Diffserv 2 = proprietary solution or Diffserv 1 = RSVP aggregation Diffserv 2 = 2 bit resource allocation scheme or

27 E2E QoS A generic Communication Scenario (2) Intserv/RSVP (inter-domain signaling) Diffserv 1 Diffserv 2 Diffserv 3 Diffserv 4 Diffserv 1 = fixed pipes Diffserv 2 = proprietary solution Diffserv 3 = over-provisioned Diffserv 4 = RSVP aggregation No per-flow state in: core routers of the 4 domains border routers of domain 3-26-

28 Conclusions -27-

29 QoS in Next Generation Networks Focus shifting from individual building blocks to E2E network configurations in relation to: Communication scenarios Number of the IP transport providers involved QoS control architecture in use Number of the IP Telephony Service Providers involved Signaling, call and AAA control architecture in use Fixed (wireline) and mobile (wireless) network environments Hetereogeneous classes of traffic with different QoS requirements -28-

30 End-to-End QoS open Issues Reference network configurations (standardization) Architectural enhancements for QoS support (enforcement and policing) Protocol extensions for QoS support E2E QoS in heterogeneous environments: seamless control architecture for fixed and mobile interworking of multi-administrative domains (multiproviders) interoperability of different networking technologies QoS support in wireless subnetworks: location dependent errors time verying channel capacity Dynamic customer choice of Class of Service -29-