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									 Policy-based QoS Framework for
     Multi-service IP Networks
                   Hoon Lee
         E-mail: hoony@changwon.ac.kr

       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

There exists no killer applications! Pack them up!!
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 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
                    Manageme         Policy         Policy
                    nt Tool        management       server


                               Policy consumer


  From                                 Traffic               Network         Static policy
                     SLS
Customer             Subscr.           Estimation            Provisioning    (Long-term)


             SLS
                                                        Resource   Route
             Req.                     Network
                                                        manag.     manag
                      SLS             monitoring                            Dynamic policy
                      Inv.                                                   (Short-term)



           SLS Management         Performance Manag. Traffic Engineering
            NTT RENA’s QoS Framework
 Separation of control and data transfer plane
  Flexible network control
 Centralized QoS management  e2e QoS


             Service/Network Control Platform NIB

                       PS         BB                           From NMS
            SCS

                                                        PSTN             Phone
    PC


    PC                                                    Video server

              e2e Optical network
                                                       Web server
    Phone    RENATM:  Resilient Network Architecture
             SCS: Session control server
             BB: Bandwidth broker
             PS: Policy-server
             NIB:Network information base
             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
 Policy-based Networking: Big Picture
      Phones

                          VoIP                             Best effort IP
       PBX                                                 network
                          G/W

           …                       Current
                           AN
  PCs/Servers
                          Router                            Core
                                            Access Premium backbone network
                Voice buffer
                                            Router         Router
                  Policy server farm                             MPLS Tunnel


          QoS            Bandwidth       VPN
         Server          Broker
          (SLA)                             Voice
                                     Data                               Access network

                                                     Traffic
        Policy Base                NIB               meter
                                                                PCs/Phones/TEs/Serv
Core node: DiffServ-based CBQ + PHB-based Scheduling + MPLS-TE  ers
Edge node: SLA negotiation, UPC, Packet classification /QoS mapping, CBQ, Packet-scheduling
                 Packet Level SLS
Service     Attributes      Application      QoS Requirements
  type                       services             (ITU-T)
                            Email, ftp,
  Data     Conventional     low quality             None
service     BE service         video

          QoS compatible     Internet      E2E delay < 150ms for
 Voice        to PSTN       telephony,      99.99% of packets,
service                     Interactive          PLR < 10-3
                            multimedia
                                TV,        E2E delay < 150ms for
 Video         New         Videoconfere     99.99% of packets,
service                        ncing             PLR < 10-4

                           IP VPN ,www,    Minimum contracted BW,
 Bundle    Interactive     on-line game,     E2E delay < 1~4sec
service                      streaming           PLR < 10-6
                            multimedia
    Mapping between DiffServ & MPLS
  QoS          Premium    Assured      Better than BE   Best-Effort
 Services       service   service          service       service


  DiffServ       EF        AF 1/2         AF 3/4           BE
   PHB

  MPLS         Platinum     Gold       Silver/ Bronze     Steel
  Label

ITU-T QoS        0/1          2             3~4             5
  Class

  Typical       VoIP      Signaling,       WWW,           e-mail
Applications    VPN          VoD            telnet,
                                         streaming
                                          service
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
              Bandwidth Reservation Model :
                        Videophone Service Architecture

                  LAN                                        ISP
                                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/pixel250200pixels/frame5frames/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
                             C
            E (C ,  )        C!      .
                           C
                                  i
                           
                           i 0   i!
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 from alternate route of the neighboring 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:
    Number of     Required number of channel   Total Required Bandwidth
    subscriber      (residential / business)    (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 :
                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
                          Voice
                          packet                   SP

                          Data1
                          packet                   C

                          Data 2
                          packet

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
Mean waiting times for M/G/1 queue with SP service:
            k 1 k E[ k 2 ]    R
               3

     W1 
               2(1  1 )
                       R
     W2                             ,
            (1  1 )(1  1   2 )

                             R
     W3                                         ,
            (1  1   2 )(1  1   2   3 )

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

                2 1  CS
                1       2
                             CS2=squared coefficient of variation for
     WFIFO  (           ).
             1     2          service time of a packet
     Numerical Experiments
Source traffic profile:
 - Voice source: G.711 Voice coder, 216bytes
 - Data source: Ethernet frame, Pareto distribution,
                             m
   F (l )  Pr{L  l}  1  ( ) , (l  m,  0).
                             l
   Minimum packet size, m: 500~1500bytes
   Tail index: =3

Link capacity per output port: 1M, 10M, 100Mbps
            Traffic Load Type
Load   1      2    3    
Type
                                 Light-voice
 A     0.1     0.4   0.4   0.9
                                 Heavy-data

 B     0.3     0.3   0.3   0.9

 C     0.5     0.2   0.2   0.9
                                 Heavy-voice
 D     0.7     0.1   0.1   0.9
                                 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 isolates voice traffic from non- voice traffic”
     does not hold!
     This is more evident for the WFQ-families.
    Delay Performance of Data Traffic
Performance comparison between different classes:
         W2      1                      W3       1  1
                        .                                      .
         W1 1  1   2                W2 (1  1   2   3 )


                                        1=0.2

            1=0.4
                                                   2=0.4
                     1=0.2
                                                            2=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.

								
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