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Providing Guaranteed Services Without Per Flow Management By: Ion Stoica, Hui Zhang Presented by: Sanjeev R. Kulkarni Outline Problems with the current QoS architectures Stateless Core Architecture(SCORE) Dynamic Packet State Core Jitter Virtual Clock Algorithm Admission Control

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Providing Guaranteed Services Without Per Flow Management

By: Ion Stoica, Hui Zhang

Presented by: Sanjeev R. Kulkarni

Advanced Computer Networks


Outline l.jpg
Outline

  • Problems with the current QoS architectures

  • Stateless Core Architecture(SCORE)

    • Dynamic Packet State

    • Core Jitter Virtual Clock Algorithm

    • Admission Control

  • Implementation details

  • Extensions to IPv6

Advanced Computer Networks


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Current QoS architectures

  • Integrated Services

  • Differentiated Services

Advanced Computer Networks


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Integrated Services

  • All Routers maintain per-flow state

  • State

    • Control Plane

      • Admission Control: per flow signaling

    • Data Plane

      • Classifier: per flow flow-ids

      • scheduler: per flow scheduling algorithm parameters

Advanced Computer Networks


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Integrated Services

  • All Routers maintain per-flow state

  • State

    • Control Plane

      • Admission Control: per flow signaling

    • Data Plane

      • Classifier: per flow flow-ids

      • scheduler: per flow scheduling algorithm parameters

  • Scalability??

Advanced Computer Networks


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Jitter Virtual Clock

  • For each packet

    • eligible time

    • deadline

  • Scheduling done in the order of the deadline

    • e1i,j = a1i,j

    • eki,j = max ( aki,j + gki,j-1, dk-1i,j)

    • dki,j = eki,j + lki/ri

Advanced Computer Networks


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Core-routers and Edge routers

Advanced Computer Networks


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Differentiated Services

  • A small number of traffic classes

  • Only Edge routers maintain per flow state

  • Control Plane

    • Admission Control: per flow signaling

  • Data Plane

    • Classifier: per class classification

    • Scheduler: per class scheduling

  • Advanced Computer Networks


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    Differentiated Services

    • A small number of traffic classes

    • Only Edge routers maintain per flow state

    • Control Plane

      • Admission Control: per flow signaling

  • Data Plane

    • Classifier: per class classification

    • Scheduler: per class scheduling

  • Quality of QoS??

  • Advanced Computer Networks


    Stateless core solution l.jpg
    Stateless Core Solution

    • Idea similar to DiffServ

    • Only Edge Routers maintain per flow state

    • Dynamic Packet State (DPS) is inserted into each packet by edge routers

    • Core routers update DPS and schedule packets accordingly

    Advanced Computer Networks


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    DPS

    Ingress

    Egress

    Advanced Computer Networks


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    How it works

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    Advanced Computer Networks


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    How it works

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    Advanced Computer Networks


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    How it works

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    Advanced Computer Networks


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    How it works

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    Advanced Computer Networks


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    How it works

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    Advanced Computer Networks


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    How it works

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    Advanced Computer Networks


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    How it differs from DiffServ

    • DPS versus Per Hop Behavior (PHB)

      • DPS is dynamic

      • Routers change DPS and schedule packets based on the DPS state

      • DPS change mirrors a Core-Jitter Virtual Clock scheduling

    Advanced Computer Networks


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    Core Jitter Virtual Clock

    • eki,j = max ( aki,j + gki,j-1, dk-1i,j)

  • The main culprit is dk-1i,j

  • Introduce a slack variable such that

    • aki,j + gki,j-1 + > dk-1i,j

  • ik =max (0, ik-1 + (lik-1 - lik)/ri -

    (ei,1k - ei,1k-1 - lik-1/ri)/(h-1) )

    Advanced Computer Networks


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    Example

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    Advanced Computer Networks


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    Example

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    ea1

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    Advanced Computer Networks


    Example22 l.jpg
    Example

    ga1

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    Advanced Computer Networks


    Example23 l.jpg
    Example

    ga1

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    Advanced Computer Networks


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    Example

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    Advanced Computer Networks


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    Example

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    Advanced Computer Networks


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    Example

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    Advanced Computer Networks


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    Example

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    gb1

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    Advanced Computer Networks


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    The algorithm

    • Parameter Initialization by Ingress Routers

    • Core routers examine the parameters and modify g

    • Egress Routers strip the packet of these labels

    Advanced Computer Networks


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    Admission Control

    r

    s

    d

    a

    c

    b

    Advanced Computer Networks


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    Admission Control

    Resv

    r

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    Advanced Computer Networks


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    Admission Control

    r

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    Advanced Computer Networks


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    Admission Control

    r

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    Advanced Computer Networks


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    Admission Control

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    Advanced Computer Networks


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    Admission Control

    r

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    Advanced Computer Networks


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    Admission Control

    r

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    Advanced Computer Networks


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    Admission Control

    Resv

    r

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    Advanced Computer Networks


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    Admission Control

    • Each core router maintains an upper bound R on the Total Bandwidth reserved

    • Local Admission Control

      • Accept if R + ri < C

    • Periodically they run an algorithm that contains the deviation between the actual B/w reserved and R.

    Advanced Computer Networks


    Recalibration algorithm l.jpg
    Recalibration Algorithm

    • Packet state b

    • Add all b values on each packet arrival

    • Periodically they update based on

      R = min ( R, RD/(1-f) + Rnew )

    Advanced Computer Networks


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    Implementation

    0

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    TOS

    IPv4 Header

    Frag Offset

    18

    Advanced Computer Networks


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    Implementation

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    18

    Flag

    F1

    F2

    F3

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    5

    9

    16

    Advanced Computer Networks


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    Extension to Ipv6

    0

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    11

    31

    Flow Label

    Flag

    F1

    F2

    F3

    6

    11

    19

    2

    Advanced Computer Networks


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    Summary

    • SCORE Network

      • Is Scalable

      • Gives a QoS similar to Jitter Virtual Clock

      • Extensible to Ipv6

      • Transparent to the outside network

    Advanced Computer Networks


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