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VoIP Quality Of Experience. Mu Han Director Microsoft Corporation. Session Objectives. Microsoft’s user-focused approach to Quality of Experience. Inside the VoIP stack of Office Communications Server 2007. Considerations for deploying OCS 2007 in a corporate network.

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voip quality of experience

VoIP Quality Of Experience

Mu HanDirectorMicrosoft Corporation

session objectives
Session Objectives

Microsoft’s user-focused approach to Quality of Experience

Inside the VoIP stack of Office Communications Server 2007

Considerations for deploying OCS 2007 in a corporate network

today s business environment what customers a re t elling u s
Today’s Business EnvironmentWhat customers are telling us


  • Need to solve problems faster
  • Need to be able to connect anytime anywhere

IT Decision Makers

  • Need to help the company to be more competitive
  • Need to invest for the future

IT Professionals

  • Need to deliver more value with less resources
  • Need to leverage existing infrastructure
the rise o f t he m obile workforce
The Rise of the Mobile Workforce
  • High-speed connectivity continues to grow more ubiquitous
  • Little tolerance for potentially complex operations
    • Setting up a virtual private network (VPN)
    • Connecting from their home broadband connection
  • User experience must be equivalent to the corporate network
    • Highest possible quality
    • Completely Secure
    • No extra steps to setup or manage

“We should anticipate the day when more than half of the information worker workforce can function productively outside of traditional facilities.”

– Heidi Skatrud, Vice President, Runzheimer International, quoted in

talking with other companies
Talking With Other Companies
  • Need to stay close to my customers, partners, and suppliers with rich communication modes
    • Connecting the communication islands with full OCS federation
    • For people who are not federated, they should still be able to join video conferences
designing for the internet
Designing for the Internet


  • Enable new scenarios – mobile worker, cross company
  • If a solution can survive the hostile conditions on the Internet, it can easily handle the Intranet


  • Loss, Jitter, Delay, Connectivity, Security, etc.
  • Administrators don’t own the network end to end


  • Intelligent endpoints with advanced software
the challenge of packet networks
The Challenge Of Packet Networks
  • Traditional IP telephony not designed for IP networks
    • Transfer of circuit switched concepts
    • Fragile CODECs, sensitive to minute network impairments
      • “Even a 1% loss can significantly degrade the user experience with G.711, which is considered the standard for toll quality” 1
      • “The default G.729 codec requires packet loss far less than 1% to avoid audible errors” 2
  • Network engineering required for traditional IP telephony

QoS and CAC work to recreate conditions of switched networks

1 - Intel: Overcoming Barriers to High-Quality Voice over IP Deployments

2 - Cisco: Quality of service for Voice over IP


“The ripe taste of cheese improves with age.

Act on these orders with great speed. “

traditional ip telephony limitations
Traditional IP Telephony Limitations



Traditional approach of QoS/CAC is complex and difficult to manage

  • Admins may not control whole network
  • Users are increasingly mobile


  • Most common source of user dissatisfaction is Voice Quality
  • Many factors affect voice quality
many dimensions of quality
Many Dimensions Of Quality


  • Getting the packet across the wire


  • Audio and Video content inside the packet


  • Caller usability and human factors


  • Understanding the user experience
microsoft s quality of experience
Microsoft's Quality Of Experience

Complete and comprehensive solution that doesn’t require QoS

Comprehensive, user-focused approach to quality

Intelligent end-points designed for the Internet

Real time metrics of actual experience

session objectives14
Session Objectives

Microsoft’s user-focused approach to Quality of Experience

Inside the VoIP stack of Office Communications Server 2007

Considerations for deploying OCS 2007 in a corporate network

the microsoft media stack
The Microsoft Media Stack

Advanced Network Layer

  • NAT/Firewall traversal
  • Secure RTP

Robust audio video processing

  • Forward error correction and error concealment
  • Time-warping jitter buffer control
  • Dynamic Adaptation to real-time network conditions

Optimizes the audio that gets into the packet

  • Noise suppression
  • Automatic gain control
  • Acoustic echo cancellation

Measurements and report of user experience

microsoft s real time c odecs rtaudio and rtvideo
Microsoft’s Real-Time CodecsRTAudio and RTVideo
  • Supports Wideband
    • Wideband greatly improves intelligibility and naturalness of speech
  • Robust under loss and jitter
    • Built-in protection to recover from lost or late packets
  • Highly efficient use of Bandwidth
    • Higher fidelity at lower bandwidth
  • Multi-rate codec
    • Enables real-time adaptation
quality of experience at work noise free
Quality Of Experience At WorkNoise free





Source: Psytechnics 12/06

quality of experience at work office environment
Quality Of Experience At WorkOffice environment





Source: Psytechnics 12/06

session objectives20
Session Objectives

Microsoft’s user-focused approach to Quality of Experience

Inside the VoIP stack of Office Communications Server 2007

Considerations for deploying OCS 2007 in a corporate network

right sizing your network
Right Sizing Your Network
  • You are adding a service to your network
    • Right provisioning is needed
  • Even with efficient CODECs, clients need bandwidth
  • Holds true for VoIP telephony or conferencing
  • Simple policies give you control
what does media take
What Does MediaTake?
  • These are one-way “on the wire” numbers
  • Numbers are worst-case
    • Silence suppression saves more bandwidth
    • Packetization dynamically changes based on usage
per user calculation
Per User Calculation
  • Type of usage is important when planning
  • Media Stack adjusts to network bandwidthchange every 5 seconds
  • Consider the whole path end-to-end
other network considerations
Other Network Considerations


  • Engineer to less than a mean of 100 milliseconds


  • Up to 10% can be handled without significant problems


  • The clients can connect through most common networks

Call Admission Control

  • Hard limits aren't required to provide quality
managing the u sage
Managing The Usage
  • Server policy
    • Limit the type of conference that can be setup
    • Limit who can setup a conference
    • Limit how many users per conference
  • Client policy
    • Limit the bandwidth used per session
    • Limit the port range used by audio and video
qos support
QoS Support
  • OCS 2007 does not require DiffServ, RSVP or CAC
  • We do work within a DiffServ environment
  • DSCP marking by the end-points
    • Audio: Expedited Forwarding
    • Video: Class 3 of Assured Forwarding
  • DSCP marking can also be tuned through policy
  • Windows Vista has centralized policy enforcement
  • Each endpoint generates detailed reports for each session
  • Server collects reports and generates alerts and high level reports
  • Use the reports to identify trends and hot spots
key takeaways
Key Takeaways
  • Microsoft’s user-focused approach to Quality of Experience
    • Designed for the Internet, more tolerant to hostile network conditions
    • Comprehensive approach
    • Built-in report of user experience
  • Microsoft’s solution is built around intelligent endpoints
    • Advanced CODECs and other signal processing for better quality
    • Advanced network stack for connectivity, security, and adaption
  • Good network design and engineering practice still matter
    • Be thoughtful about bandwidth – new services need it!!
    • Monitor and fix hot spots

Microsoft’s Quality of Experience White Paper

  • Psytechnics Study
  • Visit the OCS 2007 and Exchange Server 2007 Tech Centers

© 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.

The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation.

This document may contain information related to pre-release software, which may be substantially modified before its first commercial release.Accordingly, the information may not accurately describe or reflect the software product when first commercially released MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.