The NIProxy: a Flexible Proxy Server Supporting Client Bandwidth Management and Multimedia Service P

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The NIProxya Flexible Proxy Server Supporting
Client Bandwidth Management and Multimedia
Service Provision

• Maarten Wijnants
• Wim Lamotte

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Outline

• Introduction
• System Overview
• Software Architecture
• Bandwidth Distribution Algorithm
• An Example Service Video Transcoding
• Evaluation
• Test Application
• Experimental Results
• Conclusions Future Work

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Introduction

• Popularization of multimedia content and
  real-time multimedia streaming
• E.g. multiplayer games verbal communication
  through voice streaming
• E.g. academic applications also video
  communication
• Multimedia streaming requires considerable amount
  of bandwidth
• Client downstream bw does not always suffice
• Mechanisms are needed to maximize clients
  Quality of Experience (QoE)

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NIProxy System Overview

• The NIProxy
• Network intermediary (a proxy)
• Abbreviation for Network Intelligence Proxy
• Goal introduce more intelligence in the network
  so that it can deliver MM content to clients more
  intelligently and efficiently
• Outcome improved QoE for users

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NIProxy System Overview

• NIProxy introduces 2 kinds of intelligence in the
  transportation network
• Network awareness
• NIProxy has knowledge of the clients network
  link
• Is acquired through periodic network probing
• Current end-to-end throughput, latency, packet
  loss rate,
• Also encompasses knowledge of the bandwidth
  requirements of network streams
• Application awareness
• NIProxy is aware of the application it is serving
• Is acquired through support library called the
  NILayer
• E.g. relative importance of streams

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NIProxy System Overview

• The NIProxy provides 2 QoE-increasing mechanisms
• Automatic client bandwidth management
• Multimedia service provision
• NIProxy MM service provision platform
• Both mechanisms can exploit the NIProxys dual
  awareness/intelligence
• The mechanisms are
• Complementary
• NOT isolated entities (i.e. they can collaborate)

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Software Architecture
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Software Architecture

• Bandwidth Manager
• Responsible for managing the proxy client's
  available downstream bandwidth
• Has access to the NIProxy's bandwidth
  distribution algorithm
• Computes verdicts for the network packets it
  receives
• Accept
• Drop
• Block
• Only packets for which an accept verdict is
  computed are transmitted to the proxy client

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Software Architecture

• Service Manager
• Applies services on MM streams on behalf of proxy
  clients
• Hands intercepted network packets to the
  currently loaded (and interested) services
• Service traversing order load order
• Services are allowed to alter the contents of the
  packets they receive
• Multiple services can collaborate on a single
  stream
• Each client has its own Service Manager instance
• Services are implemented as NIProxy plug-ins

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Bandwidth Distribution Algorithm

• Manages/distributes proxy client downstream
  bandwidth by arranging MM streams in a stream
  hierarchy
• Leaf nodes actual network streams
• Internal nodes implement a certain bandwidth
  distribution technique
• Mutex (e.g. group multiple qualities of same
  stream)
• Priority (e.g. distinguish between different
  types of network streams)
• Weight (e.g. distinguish between individual
  network streams of the same type)
• Stream hierarchy is maintained by client

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An Example ServiceVideo Transcoding

• NIProxy video transcoding service
• Enables NIProxy to reduce bandwidth requirements
  of video streams
• Is implemented using the cascaded pixel-domain
  approach to transcoding
• For each received video stream, a new node is
  added to the proxy clients stream hierarchy
• Is linked to the transcoded video stream
• Is added as sibling of original video stream

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An Example ServiceVideo Transcoding

• Mode of operation
• Registers interest for video streams with Service
  Manager
• Consults proxy clients stream hierarchy
• Transcode only if Bandwidth Manager computes an
  accept verdict for transcoded version of video
  stream
• If transcoding took place, original video frame
  is replaced by its transcoded counterpart
• Subsequent services will receive transcoded frame
• Notice collaboration between services and
  bandwidth distribution algorithm!

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EvaluationTest Application

• Test application
• Simple in-house developed NVE
• Provides users with a top-down 2D view of the
  shared virtual world
• Supports voice and video communication
• Required modifications
• Provide NIProxy with application awareness
• Voice stream importance inversely proportional
  to virtual distance
• Video virtual orientation is also considered
• Maybe more meaningful for 3D NVEs
• Easy thanks to availability NILayer library

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EvaluationExperimental Results

• Experiment
• 1 proxy client, 3 regular clients (C1, C2, C3)
• Goal register MM experience provided to the
  sole proxy client
• Only 1 type of MM was considered ? video
• Places largest load on network
• Allows demonstration of video transcoding plug-in
• Consisted of 3 intervals
• Within each interval, all conditions remained
  constant
• Transition between intervals was triggered by
  changing conditions

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EvaluationExperimental Results
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EvaluationExperimental Results
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EvaluationExperimental Results

• Findings
• NIProxy respects client downstream bandwidth
• Packet loss and packet latency are kept to a
  minimum
• Improved playback of MM streams at client-side
• Client receives MM streams that are most
  important to it in the highest quality possible
• Has a positive impact on the user QoE
• Video transcoding service enables NIProxy to
  forward lower-quality video to a proxy client
• Alternative drop video all together
• NIProxy's service provision mechanism is also
  capable of improving the user QoE

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Conclusions

• Increasing use of MM content streaming
• If done improperly, can result in deterioration
  of user QoE instead of an improvement
• NIProxy
• Introduces more intelligence in the network
• Both application- and network awareness
• Complementarily leverages this awareness to
• Intelligently manage client downstream bandwidth
• Apply services on MM streams on behalf of clients
• Important feature collaboration possible
• Outcome improved MM experience for users
• Confirmed by the presented experimental results

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Future Work

• NIProxy still lacks knowledge of the client
  terminal and the end-user's preferences
• Third kind of awareness
• Process of (un)loading services is at the moment
  directed entirely by proxy client
• Migrate (some) of this control to NIProxy
• Bandwidth distribution algorithm is optimized for
  continuous streams
• Provide support for bursty, short-lived streams
• Make video transcoding service dynamic
• Transcode to range of output qualities

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Thank you for your attention!Any questions?