Transcript Link Layer Topology Discovery & Enabling Wi-Fi

Link Layer Topology Discovery
And Enabling Wi-Fi Diagnostics
For Network Performance Tuning
Gabe Frost and Glenn Ward
Windows Core Networking
Microsoft Corporation
What You’ll Learn
Top issues impacting user experience and
perception of product quality (Wi-Fi)
Hardware and Software vendors
What to support in WLAN AP to avoid
performance degradation
What to support in NIC driver to enable
diagnostics for Network Performance Tuning
The role of LLTD and additional
value provided
AV-Capable Home Networks
Consumers demand simplicity and reliability
No-new-wires
Focus on WiFi Audio/Video (AV) networks
Consumer Electronics (CE) centric, not
Information Technology (IT) centric
Multiple configuration/upgrades is costly
AV networking shouldn’t require an expert
Can’t avoid all problem conditions, so…
Actionable diagnostics necessary to remove
“magic” in network setup
Top Issues: No-New-Wires
No-new-wires networks are shared resource
2.4 GHz WiFi dominant home network
Wireless highly susceptible to performance degradation
and non-optimal setup
Backward compatibility for legacy devices
Interference from nearby networks
Microwave, cordless phone, etc. (common RF)
Concurrent use of shared network (cross-traffic)
Distance and obstructions (walls, floors, people)
Setup: Dual-band selection, unsupported topologies
5 GHz solves most (not all)
Diagnostics provided for each top issue
Diagnostics Business
Opportunity
Xbox 360 has built-in Media Center Extender
About 5 million projected sales by June
Significant Xbox WiFi adapter sales
Windows XP Media Center Edition is currently
top consumer SKU
Windows Vista Home Premium and Ultimate Editions
provide Media Center (no separate SKU/software)
Media Center Extender software licensing and
porting kit available for non-Windows
Lineup of Media Center Extenders coming
Network Performance Tuner
Validate and tune network for Media Center
Extender (MCX) use (i.e. AV networking)
Verify end-to-end throughput
Can path support Standard Definition (SD)?
High Definition (HD)?
Identify and diagnose WiFi performance
degradation on first use and during run-time
Ensure proper network setup before AV use
Inform what caused run-time quality issue
Requires NDIS6 NWF driver on Windows Vista
NPT Integral To Media Center
2.4 GHz Legacy Compatibility
802.11g theoretical 54 Mbps not possible
1/3 feasible in perfect conditions
Legacy 802.11b devices further impact perf
Any associated legacy device reduces
bandwidth by ½ or more (not sending data)
Even if not on end-to-end media path
Associated
Disassociated
Nearby 802.11 Interference
Performance impacted by co-channel and
adjacent-channel interference
E.g. 4 Mbps on co-channel will reduce
throughput by ~4 Mbps
Impacts Close-proximity dwellings
Default static channel out-of-box
exacerbates problem
NPT diagnoses and identifies
clearest channel
General RF Interference
Common household interference greatly
impacts 2.4 GHz WiFi
Microwave Oven
Cordless Phone
Connection
Loss
5 GHz (dual-band) AP solves this problem
NPT will identify if causing congestion
during run-time
Concurrent Network Use
Commonly referred to as cross-traffic
WiFi (2.4 and 5 GHz) is a shared medium, so concurrent
use reduces available bandwidth
Impacts all shared mediums, not just WiFi
Examples (contend with ongoing AV streams)
Heavy Internet use
File transfers
Network print or backup
Dual-band AP mitigates this problem
AV on 5 GHz and data-oriented on 2.4 GHz
NPT will identify if causing congestion during run-time
Source of cross-traffic must implement Link Layer
Topology Discovery (LLTD)
Detecting Cross-Traffic As
Cause Of Congestion
(Using LLTD)
Distance And Obstructions
Performance degraded if MCX and AP
are separated by walls and floors
Also moving obstructions (people)
Impacts both 2.4 GHz and 5 GHz
NPT will diagnose if causing congestion
during run-time
Common Setup Problems
Dual-band AP (5 GHz and 2.4 GHz) available,
but connected to 2.4 GHz
NPT detects this situation
Both Media Center and MCX on
same radio
Commonly referred to as double-hop
Effectively ½ available bandwidth (or worse)
Media Center wired, MCX Wireless
Double-Hop (both connected to same WiFi radio)
Link Layer Topology
Discovery (LLTD)
Glenn Ward
Microsoft Corporation
Windows® Rally™ Program
Access to
Technologies
Simple Unified
License
Technical
Guidance
Windows® Rally™ Devices
Effortless to
configure and
maintain
Reliable and simple
to manage
More secure and
provide rich digital
experiences
Windows Rally Experiences
Technologies
Management Interfaces
Function
Discovery
Discovery
Connect
SetupNow
Windows
Wireless
MapMap
Topology
LLTD:
Network
Service
QoSofExtensions
LLTD:
Quality
Applications
Plug
Device
andSpecific
Play Extensions
Drivers
AV UPnP
Devices
IP Network
(IPv4, IPv6)
Ethernet/Wireless
Experiences
Windows Rally Technologies
Device
Networked
Profile
for Web
Devices
Services
Problem Statement
Users have difficulties troubleshooting issues
on their network
Partners have few support tools for their device
and/or service
Home Networks growing in sophistication
Was: Internet Sharing for email, Web surfing
Now and future: Streaming from WAN, cross-home
Media Delivery
Latency-sensitive Broadband Services: IPTV, VoIP, Gaming
Unrealized scenarios -> product returns, smaller TAM
Home Networking complexity calls for better
infrastructure tools
Solved Via Windows Vista
Network Map/LLTD
LLTD – Link Layer Topology Discovery
Discovery, Topology and Diagnostics, below
Internet Layer
No Dependency on NID intelligence to function
Detect Legacy Hub, Switch, AP, Half-Bridge
Ensures correct problem isolation
Ensures network robustness – bandwidth,
cross-traffic detection
Windows Vista UI
Sample Map
Business Value
Raise visibility, perceived value of
networks and IP devices!
No longer plumbing component
Device Capabilities Delivery
Identified in UI
Give credit (good/bad) where due
Leverage LLTD as L2 Bootstrapping protocol
Provide you with opportunity to showcase your
Industrial Design
Brand
Device Capabilities
Porting Kit ‘Beta 1’
Contents
Source Code
Reference LLTD implementations
Test Suite
User’s Guide and FAQ
Protocol Spec
Mandatory/Optional call-outs
.ICO creation guidelines
QoS Extensions To LLTD
Provides packet time-stamping for
bandwidth and diagnostic experiments
Mandatory if your device handles
QoS-sensitive traffic (Audio/Video)
Mandatory component for all
Media Center Extender (MCX) devices
E.g. Xbox 360
Media Center must see sufficient bandwidth
Stream won’t receive priority if poor
results returned
Feature Overview
Closing Info
XP Responder: OOB Release
License
No cost, simple licensing terms
Licensees receive LLTD Porting Kit
Questions
LLTDinfo @ microsoft.com
Call To Action
IHV: Meet Designed for Windows Gold requirements
Build dual-band WLAN AP
IHV: Download LLTD reference implementation and
incorporate into router/AP and media player devices
QoS extensions critical
ISV: Implement NDIS6 Native WiFi (NWF) drivers
All OIDs required by diagnostics are mandatory in NWF
Additionally
Set lRSSI field of DOT_11_RECV_CONTEXT per-packet
NDIS_MINIPORT_ADAPTER_NATIVE_802_11_ATTRIBUTES
Set at initialization time
Additional Resources
Web Resources
Blog http://blogs.msdn.com/wndp
Windows Rally Technologies
Residential gateway implementation guide
http://www.microsoft.com/whdc/device/network/
homenet/WAP_reqs.mspx
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