confidential information ® 2008 xirrus, inc. all rights reserved principles of high performance...

Confidential Information ® 2008 Xirrus, Inc. All Rights Reserved

Principles of High Performance Wi-FiPrinciples of High Performance Wi-Fi

Brian MasonDirector of Product MarketingBrian MasonDirector of Product Marketing

Confidential Information ® 2008 Xirrus, Inc. All Rights Reserved 2

Wi-Fi NeedsWi-Fi Needs• High speed connectivity for fast transfer of large data files (e.g. CAD, simulation software, etc)

• Robust coverage for reliability on mission critical projects

• Pervasive availability for easy collaboration any where.

• Reliable enough to be considered suitable failover for wired networks

• Secure connectivity to entrust proprietary data

• High speed connectivity for fast transfer of large data files (e.g. CAD, simulation software, etc)

• Robust coverage for reliability on mission critical projects

• Pervasive availability for easy collaboration any where.

• Reliable enough to be considered suitable failover for wired networks

• Secure connectivity to entrust proprietary data


Wi-Fi NightmaresWi-Fi Nightmares

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Wi-Fi ChallengesWi-Fi Challenges

1.Higher User Density

2.Performance

3.Reliable Seamless coverage

4.Security

5.Resiliency

1.Higher User Density

2.Performance

3.Reliable Seamless coverage

4.Security

5.Resiliency


Wired Faced same problem 15 years agoWired Faced same problem 15 years ago

• Added bandwidth – Ethernet trumped ATM and Token Ring

• Dedicated Resources – Switches beat hubs

• Intelligence at the edge – Intelligent switches are the standard

• Easier Deployment – more ports, fewer devices

• Added bandwidth – Ethernet trumped ATM and Token Ring

• Dedicated Resources – Switches beat hubs

• Intelligence at the edge – Intelligent switches are the standard

• Easier Deployment – more ports, fewer devices


Wireless Following Wired’s leadWireless Following Wired’s lead

Six Trends in wireless making this possible:

1. Standardization of 802.11n (Increased Bandwidth)

2. Move from 2.4GHz to 5GHz (Increased Bandwidth)

3. Multi-Radio devices (Greater Capacity)

4. Directional Antennas (Greater range, fewer devices)

5. Embedded Threat Sensors (Increased Security)

6. Integrated Spectrum Analyzer (Easier Troubleshooting)


• Should be ratified June 2009•Faster

Up to 100 Mbps with first-gen pre-N productsUp to 300 Mbps with 802.11n draft 2.0 productsAmple bandwidth makes it easier for a single WLAN to support a mix of voice, video and data

•Farther

More than 300 feet vs. 100 feet with 802.11a/b/gPotential for lower infrastructure costs because fewer access points (APs) required to blanket an area

802.11n: The Basics802.11n: The Basics


• More Robust

MIMO technology mitigates interference and maintains broadband performance even with weak signals

• More Secure

Wi-Fi Alliance certified 802.11n draft 2.0 products must include Wi-Fi Protected Access 2 (WPA2)

802.11n: The Basics802.11n: The Basics


802.11n – Obtaining Higher Data Rates802.11n – Obtaining Higher Data RatesSpatial Multiplexing

Source data stream split and sent over separate antennas at the same timeRecombined at receiver using MIMO

signal processingDoubles, triples, or quadruples the

data rate depending on the number of transmit antennas used

Channel BondingIncreasing the Bandwidth

Bonds two 20MHz channels to a 40MHz channel Slightly more than doubles the bandwidthPhased channel operation: ability to jump between 20 and 40Mhz channels


802.11n – MAC Improvements802.11n – MAC ImprovementsReducing Overhead Improves Efficiency

Frame AggregationBlock ACKsReduced Inter-frame spacing


802.11n802.11nRange and Data Rates

Longer Range or Higher Data RatesWi-Fi Certified data rates 300Mpbs Most compatible with 802.11aBackwards compatible with 802.11bg • Channel Bonding• Multiple Input/ Muliple Output (MIMO)• Spactial Multiplexing


5GHz vs 2GHz Spectrum5GHz vs 2GHz Spectrum


802.11 Channels – Cell Planning 802.11 Channels – Cell Planning 802.11b/g Channels Available = 3

Distance to cell with same channel is less than a single cellSensitive to co-channel interference (from other

cells on the same channel)If energy is weak, seen as interferenceIf energy is strong, stations will deferBleed-over retards higher data ratesGreatly reduces overall network capacity

802.11a Channels Available = 23High Performance: 8 times the capacityFar less interference from cells on same channelMore channels to avoid interference


802.11 Channels – Interference Issues 802.11 Channels – Interference Issues 802.11b/g uses the 2.4 GHz ISM band

Common devices cause interferenceBluetooth devicesCordless phonesMicrowave ovensX10 wireless video camerasHAM radio operators

Interference collides with the intended signalTransmissions are garbled and data packets are retransmittedReduced end-user throughput and increased latency of data traversing the RF network

802.11a uses the 5GHz UNII bandRelatively interference free


802.11n Rates and Modes802.11n Rates and Modes802.11a/n (5GHz)

23 channels * 150Mbps = 3.4Gbps

802.11a (5GHz)23 channels * 54Mbps = 1.2 Gbps

802.11g/n (2.4GHz)3 channels * 150Mbps = 450 Mbps

802.11g (2.4GHz)3 channels * 54Mbps = 162 Mbps

802.11b (2.4GHz)3 channels * 11Mbps = 33 Mbps

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Multi-Radio vs Dual-radio ArchitecturesMulti-Radio vs Dual-radio Architectures

Multiple Radios in a single AP (i.e. an Array) = MORE CAPACITY

- Traditional APs have one or two radios

- New multi-radio architectures have up to 4, 8, or 16 radios in a single device

- Each radio has fixed bandwidth

- Each radio can support a limited number of users at one time

In a classroom of 30 students a dual radio AP will have 15 students per radio

Traditional AP: Multi-Radio

In the same classroom an Array would just have 2 or 3 students per radio


Directional vs Omni-DirectionalDirectional vs Omni-DirectionalDirectional Antennas = GREATER RANGE

Better antenna gain Better receiver sensitivityAllows fewer devices cover a larger areaTypically 75% fewer devices and cable drops required


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Distributed vs CentralizedDistributed vs CentralizedDistributed = HIGHER PERFORMANCE

Packet Processing at edgeControl plane at edgePolicy and security enforcement at edgeEncryption processing at edgeJust like Ethernet Switching Central management

Central Controller + Thin Aps Packet Processing at coreControl plane at corePolicy and security enforcement at coreEncryption processing at coreCentral management

Centralized Processing Distributed Processing


SecuritySecurity•Security Performance

Use Line-rate Hardware Based EncryptionAES (WPA2) is Best

Hardware based encryption on client

Best to Use a Single Encryption Mode per SSIDAuthentication: 802.1X

RADIUS Servers should be local

PMK Sharing = faster roamingIntrusion Detection

Threats, Attacks, ComplianceNeighboring NetworksRequires: Dedicated Radio for RF Monitoring

Time sharing radios for IDS reduces performance especially for voiceYou cant fix a problem if you don’tknow there is a problem

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Access Point /Array

AuthenticationServer

EthernetSwitch

Hardware-Based Line-Speed Encryption

Encryption Engine

DedicatedMonitorRadio


Wi-Fi ArrayWi-Fi Array•The Xirrus Wi-Fi Array

Single DeviceSuperior Range and Capacity75% Less Devices and CablingUp to 16 Modular Radios802.11n UpgradeableAdvanced RF ManagementRedundant Radios and EthernetIntegrated Wi-Fi SwitchIntegrated Spectrum Analyzer Integrated Threat MonitorLine Speed Hardware-based EncryptionFiltering and Firewalling Complete Suite of Management and Planning ToolsPlan for the Success of your Wi-Fi Network!

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Wi-Fi Sponsor ’06 & ‘07

Best Design of the Year

B e s t S t a r t u p

Array Controller

Radio ModulesAntennas


The Future of Wi-FiThe Future of Wi-Fi“The only effective way to deliver high-performance Wi-Fi is to have a centrally managed intelligent edge network – just like your wired networks do”


Wi-Fi Reference Poster SeriesWi-Fi Reference Poster SeriesXirrus Wi-Fi Reference Posters

Register at: www.xirrus.com/libraryEmail: [email protected]

Posters in the Series802.11a/b/g802.11n PrinciplesWi-Fi AuthenticationWi-Fi EncryptionWi-Fi Range DynamicsWi-Fi Network ArchitecturesWi-Fi Cousins & NephewsHigh Performance Wi-Fi

Also:Reference Poster PodcastReference Poster Companion GuidesWebinarsWhite PapersDesign Guides


ThanksThanks

Visit www.xirrus.com for

- Wi-Fi posters- 802.11n webcast and

podcast- Best Practices and design

guides- Wi-Fi gadgets and widgets

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