Quality Windows AV Experience qWAVE and Network Quality of Service QoS

1
Quality Windows AV Experience (qWAVE) and Network
Quality of Service (QoS)

• Gabe Frost
• Program Manager
• US Transports ConnectivityWindows Network
  Developer Platform
• Microsoft Corporation

2
Session Outline

• Microsoft view of network QoS
• Home QoS scenarios
• Introduction to Problem
• Why enabling scenarios is difficult
• Achieving Scenarios
• Windows Platform Support
• Call to Action

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Session Goals

• Should leave this session with the following
• Better understanding of user scenarios within the
  home where QoS is important
• Better understanding of wireless audio/video (AV)
  streaming challenges
• Knowledge of network QoS standards
• Knowledge of why diagnostics and coexistence is
  essential for the home AV ecosystem

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Windows Connect NowThe Windows Networking and
Device Connectivity Platform

• Effortless
• It Just Works experience for users
• Simple protocols, APIs and DLLs for partnersand
  developers
• Secure and Reliable
• Built-in security to enable higher user
  confidence
• Make reliability a fundamental part of the
  solution
• Foundation for the Future
• Continue enabling compelling new user experiences

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Windows Connect Now Programs
For questions email wcn _at_ microsoft.com
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Windows Connect Now Technologies
Applications
Devices Class APIs (Digital Still
Cameras, Portable Media Players, Printers, etc.)
WMC, Media Renderers, MCE
Function Discovery
WCN Configuration
qWAVE
Network Topology
WS-D, UPnP
MTP/IP, RDP, other
PnP-X
IP Network (IPv4, IPv6)
Ethernet/Wireless
Windows Connect Now Technologies
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Microsoft View of Network QoS

• Key principle network QoS provides better user
  experience
• Prioritizing network traffic isnt enough
• What if network devices dont support QoS?
• Must understand network conditions and adjust to
  them
• Network agnostic technologies are important

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Home QoS Scenarios

• Audio/Video (AV) distribution within the home
• Media Center PCs Extender devices
• Windows Media Connect
• DLNA media servers/players (Digital Living
  Network Alliance)
• WAN applications
• Gaming (Xbox)
• VoIP (Voice over IP)
• VoD (Video on Demand)
• Non-AV applications
• E-mail
• Peer-to-peer, etc.

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Home QoS Scenarios

Family Room
Den
Media Center Extender (MCX)
HDTV
Media Center PC
HDTV
Media Center Extender
Kids Room
Master Bedroom

• Concurrently sourced content from Media Center PC
• HDTV to WiFi connected MCX in family room
• HDTV to Ethernet connected MCX in master bedroom

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Home QoS Scenarios

Family Room
Den
Print
Media Center Extender (MCX)
HDTV
Media Center PC
HDTV
Media Center Extender
Longhorn PC
Kids Room
Master Bedroom
Neither ongoing TV experience is affected by
kids large term paper sent to WiFi connected
printer
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Home QoS Scenarios
Family Room
Den
Media Center Extender (MCX)
Voice
HDTV
Media Center PC
Game
HDTV
Media Center Extender
Longhorn PC
Xbox
Kids Room
Master Bedroom

• VoIP call from den is not affected by
• Ongoing TV streams
• Online game in kids room

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Introduction to Problem WiFi Bandwidth

• Wireless is dominant home network technology
• Bandwidth is unstable!
• Steady-state bandwidth changes during course of
  day
• e.g. Higher evening weekend use of neighbor
  WiFi, etc.
• Instantaneous-state bandwidth can change
  drastically
• Radio frequency (RF) interference Microwave
  oven, cordless phone, etc.
• Need to inform app about bandwidth changes
  real-time

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Introduction to Problem WiFi Bandwidth

• Bandwidth is unstable!
• Room characteristics affect available bandwidth
• Furniture, walls, floors, etc.
• 802.11b station on 11g network will lower
  bandwidth even if not transmitting
• Large amount of UDP traffic can cause
  commercially available APs to do bad things
• Hang, stop transmitting packets, etc.
• Need to protect network from being stressed too
  far
• But wait, it gets worse

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Introduction to Problem Moving Obstructions

• Commercially available 802.11a AP
• Person moving around the room during AV stream
• 802.11a is not as susceptible to RF
  interference but
• Room characteristics and obstructions still
  major issue
• But wait, it gets worse

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Introduction to Problem Multiple Streams

• What about multiple streams?
• QoS priority protects AV from data, not from
  other AV
• Need way to protect AV streams from one another
• Not much WiFi bandwidth, so AV contention is
  likely
• Need way to inform user why their stream isnt
  working
• Need way for user to specify which stream is most
  important
• TCP vs. UDP
• Some media servers stream AV with TCP, others
  with UDP
• TCP will ALWAYS back off in the presence of
  congestion
• UDP has no flow control, so blasts away
• Need way to protect TCP AV traffic from UDP AV
  traffic

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Achieving Scenarios

• To achieve scenarios, we have to think about
• Interoperability (standards)
• The role of policy
• Coexistence with multiple AV sources
• Solution to wireless challenges

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Achieving Scenarios QoS Standards

• IEEE 802.1p (Ethernet layer-2 tag)
• Priority field in 802.1Q VLAN tag
• Possible values defined by IEEE 802.1d Annex G
• Must be supported by source NIC network
  switches
• WMM (802.11 Wireless Multimedia)
• Layer-2 priority similar to Ethernet 802.1p
• 4 possible values (BG, BE, VI, VO)
• Must be supported by both NICs, and WLAN AP

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802.1 What?

• 802.1p priority defined within the 802.1Q VLAN
  tag
• Possible priority values defined by 802.1d Annex
  G

802.1d Annex G 0 Best Effort 3 Images 5
AV 6 Voice 7 Network Control
802.1p
Ethernet Frame
802.1Q
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Achieving Scenarios QoS Standards

• DSCP (layer-3 DiffServ Code Point)
• Field in IP header (network medium agnostic)
• Must be supported by infrastructure devices
• WLAN AP and router
• Digital Living Network Alliance QoS Guidelines
  (DLNA v1.1)
• Defines what layer-2 and layer-3 tags to use for
  traffic types
• UPnP QoS 2.0 (Universal Plug-n-Play)
• Defines messaging for QoS priority management

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Achieving Scenarios Role of Policy

• Used to arbitrate conflicts
• Need way for user to specify what is most
  important
• Family room media player more important than
  device in kids room
• Internet traffic from Dads app is more important
  than kids apps
• Need rich policy more than SRC/DST IP address
  port num
• Home user doesnt understand technical
  information
• Username, device name, app name, etc.
• Enables rich user experiences
• Does not solve insufficient bandwidth
• Cant create new bandwidth

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Achieving Scenarios Coexistence

• Many devices from myriad platforms have to
  peacefully exist in the home
• UPnP QoS 2.0 Device Information Sharing
• Devices notify when starting/stopping an AV
  stream
• Other devices know when to play nice
  (coexistence)
• Devices (e.g. AP) expose info about network
  traffic they know about
• Let user know why AV stream is broken
  (diagnostics)
• Rich info helps user make policy decisions
• Doesnt protect AV streams from each other
• Apps should use the event messaging to better
  coexist

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Achieving Scenarios Wireless Challenges

• Wireless is volatile each host has a different
  experience of the network
• Room characteristics (walls, floors, furniture)
• Moving obstructions (people, doors)
• Interference (neighbor WiFi, cordless phone,
  microwave)
• Centralized solutions for admission control are
  meaningless for WiFi
• Necessary to measure end-to-end bandwidth
• Solution Microsoft qWAVE platform

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Windows Platform qWAVE

• Quality Windows AV Experience
• Next-generation Windows codenamed Longhorn QoS
  API
• Provides transparency to all home QoS standards
• Ethernet / WiFi layer-2 layer-3 packet priority
  marking
• DLNA QoS guidelines
• UPnP QoS 2.0 messaging (post-Longhorn update)
• Gives home media apps access to new QoS
  technologies

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Windows Platform qWAVE

• Detect monitor LAN bandwidth
• Used for run-time feedback so apps can
  dynamically adjust to network bandwidth changes
• Hosts can transrate to quickly adapt to network
  changes
• Discover QoS capability of home network
• Legacy devices sometimes drop packets or crash
• Distributed admission control for fair
  consistent usage of network priority
• Multiple media sources require distributed
  coordination
• If insufficient bandwidth, stream can start, but
  not with priority
• Only admitted streams get high priority
• Diagnostics enables user to distinguish problems
• Provide user with actionable info to take steps
  to resolve problems

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Windows Platform qWAVE

• Shipped in Windows XP Media Center 2005
• Technology has matured through ship cycles
• Targeted usability studies have influenced
  scenarios
• Broadly available to developers in Longhorn Beta
  1
• Solution for applications that
• Distribute/stream multimedia real-time content
• Want network priority (packet marking)
• Are affected by wireless volatility

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qWAVE Architecture
Applications / Services
Presentation Framework
Distributed AV Application Interfaces
Drivers / OS Components / Core Media Components
QoS Admission Control
Diagnostics
Feedback
Runtime Enforcement
ProbeGap
Initialization
Local
Packet Pair
utilization
Throttling
Route Check
Overload
Marking
Discovery
Devices
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Call To Action

• Hardware
• Support 802.1p tagging for Ethernet (802.3)
  products
• Enabled by default
• Support WiFi WMM certification for 802.11
  products
• Support NDIS 6.0 OIDs
• Enable/disable Interrupt Moderation
• Wireless STATISTICS
• For WLAN AP and router products
• In addition to 802.1p WMM, support DSCP tagging
• WCN Link Layer Topology Discovery (LLTD)
• With timed-probe extension

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Call To Action

• Software
• Use qWAVE on Longhorn
• All-in-one solution, including wireless
  challenges
• Transparently enables/complies to myriad QoS
  standards
• Use DLNA 1.1 guidelines (QoS is defined in 1.1)
• Implement UPnP QoS 2.0 in your products
• WLAN AP, gateway device, AV devices
• Diagnostics, coexistence, and rich policy effort
• qWAVE targeted to enable in post-Longhorn update

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Community Resources

• Windows Hardware Driver Central (WHDC)
• www.microsoft.com/whdc/default.mspx
• Technical Communities
• www.microsoft.com/communities/products/default.msp
  x
• Non-Microsoft Community Sites
• www.microsoft.com/communities/related/default.mspx
  
• Microsoft Public Newsgroups
• www.microsoft.com/communities/newsgroups
• Technical Chats and Webcasts
• www.microsoft.com/communities/chats/default.mspx
• www.microsoft.com/webcasts
• Microsoft Blogs
• www.microsoft.com/communities/blogs

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Additional Resources

• Email
• qWAVE API can be found in Longhorn SDK
• Related Sessions
• Network Topology Connectivity Visualized
  (discusses LLTD)

qosapi _at_ microsoft.com
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questions