Policy-based QoS Framework for Multi-service IP Networks Hoon Lee E-mail: firstname.lastname@example.org Network and Service Assurance Lab. Dept. of Information & Communications Engineering Changwon National University Changwon, Korea
Service Trends:Triple Play=Voice+Data+Video Voice from Phone Data from PC VoD/ TV Videophone 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 There exists no killer applications! Pack them up!!
Technologies 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 TEQUILA Policy ManagementTool Policy management Policy server Policy consumer Static policy (Long-term) Dynamic policy (Short-term) Network Provisioning Traffic Estimation From Customer SLS Subscr. SLS Req. Route manag Network monitoring Resource manag. SLS Inv. SLS Management Performance Manag. Traffic Engineering
BB PS • Separation of control and data transfer plane Flexible network control Centralized QoS management e2e QoS NTT RENA’sQoS Framework Service/Network Control Platform NIB From NMS SCS PSTN Phone RENATM: Resilient Network Architecture SCS: Session control server BB: Bandwidth broker PS: Policy-server NIB:Network information base PC PC Video server e2e Optical network Web server Phone
Policies 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
… PCs/Servers Phones Policy-based Networking: Big Picture Best effort IP network VoIP PBX G/W Current AN Router Core Router Premium backbone network Access Voice buffer Router Policy server farm MPLS Tunnel QoS Server (SLA) VPN Bandwidth Broker Voice Access network Data Traffic meter Policy Base NIB PCs/Phones/TEs/Servers Core node: DiffServ-based CBQ + PHB-based Scheduling + MPLS-TE Edge node: SLA negotiation, UPC, Packet classification /QoS mapping, CBQ, Packet-scheduling
Service type Attributes Application services QoS Requirements (ITU-T) Data service Conventional BE service Email, ftp, low quality video None Voice service QoS compatible to PSTN Internet telephony, Interactive multimedia E2E delay < 150ms for 99.99% of packets, PLR < 10-3 Video service New TV, Videoconferencing E2Edelay < 150ms for 99.99% of packets, PLR < 10-4 Bundle service Interactive IP VPN ,www, on-line game, streaming multimedia Minimum contracted BW, E2Edelay < 1~4sec PLR < 10-6 Packet Level SLS
QoS Services Premium service Assured service Better than BE service Best-Effort service DiffServ PHB EF AF 1/2 AF 3/4 BE MPLS Label Platinum Gold Silver/ Bronze Steel ITU-T QoS Class 0/1 2 3~4 5 Typical Applications VoIP VPN Signaling, VoD WWW, telnet, streaming service e-mail Mapping between DiffServ & MPLS
Bandwidth 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
ISP LAN Bandwidth Reservation Model : Videophone Service Architecture Internet traffic Video Phone Cd IP Network (DiffServ) E-S/W Router … Cv = ? … E-S/W Cv=C C: Number of videophone connection (channel) : Bandwidth of a videophone connection
Input 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 Model Assumption on the session: Session arrival: Poisson arrival Session duration: Exponential distribution System model: Infinite number of traffic sources Full availability link M/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
Results and Discussion Typical 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 fromalternate route of theneighboring nodes: Cv Final= 2 Cv=1.3Gbps Final result.
Comparison: Residential vs. Business When 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:
Voice packet SP Data1 packet C Data 2 packet Bandwidth Share Model : Strict 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?
System 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 Performance R Mean waiting times for M/G/1 queue with SP service: Mean waiting time for M/G/1 queue with FIFO service: CS2=squared coefficient of variation for service time of a packet
Numerical 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
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 Traffic Load Type Light-voice Heavy-data Heavy-voice Light-data
Waiting Time of Voice Packets for Different 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 Different Service Schemes m2=m3=1,000 bytes, C=1Mbps The conventional wisdom of “SP isolatesvoice traffic from non- voice traffic” does not hold! This is more evident for the WFQ-families.
2=0.4 2=0.2 Delay Performance of Data Traffic 1=0.2 1=0.4 Performance comparison between different classes: 1=0.2
Summary 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.
References [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.