Spectrum Analyzers are Not All Created Equal David Stiff, Product Line Manager Manager,, Cisco Michael Rhoades, IT Administrator, Administrator, North American Höganäs
• Interference Impact on Network Performance • Detection, Classification and Isolation • Standalone vs. System Level Solution • What to do About Interference?
Höganä anäs s AB - Cus Custom tomer er Cas Case e Stu Study dy • Hög
“
I can’t do my job
“ ”
without wireless. It has to work.
Continued Growth and Reliance on Wi-Fi Devices
VS
Wireless is besteffort. I can’t support
a level 1 SLA.
”
IT Lacks RF Resources and Expertise
Limited Spectrum SYSTEM OVERLOAD!
Performance
802.11n 802.1 1n Performance Decrease Support Cost
$
$
$
Increase in Support Cost
$
Throughput Reduction Near
Far
(25 ft)
(75 ft)
2.4 or 5 GHz Cordless Phones
100%
100%
Video Camera
100%
57%
90%
75%
Microwave Oven
63%
53%
Bluetooth Headset
20%
17%
DECT Phone
18%
10%
Interference Type
End User Impact
Reduced network capacity and coverage
Poor quality voice and video
Potential complete link failure IT Manager Impact
Potential security breaches
Support calls
Increased cost of operation
Wi-Fi (busy neighbor)
802.1 11a/b/ 1a/b/g/n g/n - CSMA/ CSMA/CA CA or LBT (Liste (Listen n Before Talk) • 802. • Collision Avoidance – 802.11 very very polite – by design CCA – Col ollilisi sion ons s - SNR
• CCA – Clear Channel Assessment Energy Detect – quick – low power power - prone to to false positive positives s Wi-Fi Preamble – takes time – power – less prone to false
• CCA threshold for 802.11b/g is -65 dBm
802.11a is different -65 dBm ED, if true then 20 dB • CCA for 802.11a lower for Preamble interrogation needs to be processed -85 dBm
• Colli Collisions sions - Non Wi-Fi Wi-Fi device devices s do not not particip participate ate in our CA
mechanism – they have their own • No respect for Wi-Fi – results in:
Corrupted packets Increased retransmission retransmissions s Increased Duty Cycle Less available bandwidth • SNR – Signal to Noise ratio
High SNR
Energy Levels Noise Signal
Low SNR
• Duty Cycle of interference is directly proportionate to
channel time available • Busy network – less interference tolerance • Less busy – might not even notice low levels of interference • Bandwidth is like Money – the more you get the more you
spend
• A Wi-Fi chip is a communications processor – a MODEM • It only knows
Energy that can be demodulated = Wi-Fi Energy that can not be demodulated = Noise • Noise is complicated! It can be caused by: Collisions, fragments, corruption, …
Wi-Fi that is below sensitivity threshold of the receiver • Peaks in Wi-Fi activity can cause all of the above to occur • Allowing Automatic & Fast channel changes purely based on noise
leads to network instability from sporadic re-channeling
Spectrum Analysis Analysis with no compromise to data throughput Typical Wi-Fi chipset Typical Spectral Resolution at 5 MHz
Microwave oven
?
Cisco CleanAir Wi-Fi chipset Spectral Spect ral Resolution Resolution at at 78 to 156 KHz
r e w o P
Microwave oven
BlueTooth BlueTooth
BlueTooth ooth Inter Interfere ference nce ‘Chip View Visualization’ of Microwave oven and BlueT
r e w o P
Detect & Classify
100
• Custom CleanAir ASIC with with 4 cores:
35
SAgE, DSL, CPU, and Wi-Fi
Uniquely identify and track multiple interferers Assess unique impact to Wi-Fi performance Monitor AirQuality
• SAgE has an additio additional nal 500K 500K gates
for SI • SAgE is the spectru spectrum m analyzer analyzer that
was used on the Spectrum Expert Cards (Spectrum Analysis Engine)
2.4 GHz
5 G Hz Hz
• All Detection & Classification done in
ASIC at AP • No impact to data forwarding • Minimal info passed to controller
Antenna
How? Non Wi-Fi Energy Detection FFT, Pulse routines, etc Signal Isolation
SAgE
Wi-Fi
1 GB Data Stream/Sec
Energy Stream Analysis Interference Classification
DSP
CPU
Inside the CleanAir ASIC
Cisco Unified Wireless Network 7.0 Release • 2.4 GHz only
Bluetooth Link Bluetooth Discovery 802.11FH Microwave Oven Industrial wireless/ wireless/802.15.4 802.15.4 Xbox • 5 GHz only
Radar WiMAX Wi MAX Mo Mobi bile le WiMAX Wi MAX Fix Fixed ed
•
2.4 or 5 GHz Jammer Wi-Fi Inverted Wi-Fi Invalid Channel Continuous Transmitter Video Camera SuperAG Canopy Other (i.e. unclassified devices) TDD Transmitter DECT-like Phone
1. Classifiers are expandable over time with software upgrade. 2. All third party trademarks are the property of their respective owners.
Definite Security Threat Devices Potential Security Threat Devices Performance Impacting Devices
Air Quality is a measurement of nonWi-Fi and adjacent channel Wi-Fi interference All Individual devices when Classified Classi fied are assigned assigned a Severity Severity Value. A Severity of 0 is not severe, a Severity of 100 is very severe. For the same device – severity will differ on each reporting AP because of the AP’s AP’s RF relationship to that
device
Good
Air Quality is a measure of all Devices/Severities within a Radio, Floor,, Building, or Campus Floor
Bad
• Persistent Device Avoidance – PDA
Operates on Interferer Classification on a per AP basis RRM’s channel picking algorithm against the “PDA Once set – biases RRM’s channel” for the detecting AP only
Remembers interference and avoids placing the AP back on the same channel • Energy Detect RRM or “ED -RRM”
Fast acting (=< 30 seconds) Triggered by AQI value on a per AP basis Designed to prevent catastrophic interference from disrupting channel/clients NOTE: Only Available Available with full CleanAir enabled installation – not overlay
Enabled Per Band Same on WCS or WLC EDRRM has threshold variable WLC GUI - Wireless Wireless=>802 =>802.1 .11a/b 1a/b=>RRM= =>RRM=>DCA >DCA WCS – Configure=>controllers=>802.11a/b=>RRM=>DCA
ED-RR EDRRM M AQI thr thresh eshold olds: s: Low – 35 Medium (default) – 50
• Multiple APs APs = Multiple Sensors • Each AP assigns a Psudo-MAC
to an identified device
• WLC compares Psudo-MACs
from each AP and merges devices seen into one physical interferer when appropriate. • MSE calculates location of the
one, real device . • Prevents False reporting and alert
proliferation. • Aids in quick troubleshooting.
Easy to find THE interfering device.
90
• Reactive troubleshooting used when interference suspected • Fly the expert onsite with expensive tools • Live troubleshooting in a production environment • Resolution can be time consuming • Challenges Requires expertise Hard to find the interferer No continuous monitoring Lengthy resolution time Travell & time & cost requirements Trave
Cisco Spectrum Expert
Keys to Success 1. Contin Continual, ual, system system-wide -wide discovery discovery to recognize interference exists
y t i l i b a i l e R e s a e r c n I
2. Accura Accurately tely identif identify y source(s) source(s) of interference and scope the impact 3. Take intelligent, intelligent, automatic automatic action to avoid current and future interference
Reduce OpEx
Features
Benefits Self Healing and Optimizing
Reduces Downtime, Maximizes Resilience
Troubleshooting Forensics Lowers Problem Resolution Time/Cost
Wireless Security Improves Visibility to New Threats
Policy Enforcement Enables Enforceable Rules
AirQuality AirQuali ty Awa Aware re RRM Event Driven RRM Persistent Device Avoidance Remote Client Trou Troubleshooting bleshooting Spectrum Expert Connect Location, Impact Analysis & History Playback New Rogue Threats Detection (off-channel, inverted) DOS Jammer Detection Unwanted Device Notification Unwanted Device Location
Licensing Requirements
Product AP3500
None
Functionality
Wireless LAN Controller
Standard per AP
MSE
NCS
Context Awa Context Aware re clien clientt license license required for each interferer tracked MSE adds support for 100 interferers when AP3500 present (5 per AP, additive)
Standard per AP count
Multi-interferer Detection & Classification AirQuality AirQua lity Monito Monitoring ring Self-Healing Event Driven RRM AirQuality Awar AirQuality Aware e RRM Self-Learning Persistent Device Avoidance Spectrum Expert Connect AirQuality AirQua lity and Interferer Interferer Alerts Alerts Interferer Tracking and Merging Location Calculations History Storage
Remote Client Troubleshooting AirQuality AirQua lity Visua Visualization lization and Mapping Mapping Forensics Tools Location Visualization Impact Analysis History Playback
North American Höganäs Wireless Implementa Implementation tion
Michael Rhoades IT Administrator
• Höganäs AB • Based in Höganäs Sweden • Worlds Largest producer of
Iron Powders Multi-National ional Company • Multi-Nat • Publically held and traded on
the Swedish Stock Exchange in Stockholm
• 4 Sites in the US
Hollsopple, PA (Stony Creek Plant (HQ)) Johnstown, Johnsto wn, PA PA St Mary’s, Mar y’s, PA PA
Niagara Falls, NY • 360 Employees
2 Full time IT Staff • Microsoft Environment
• Cisco Unified Communications
(Version 8.5) • Cisco Unified Messaging • Cisco Unified Presence • Cisco Catalyst 3750 Series
Core Switch MDF • 22 – Cisco Catalyst 3560 IDF’s
• Large Warehouse with
500,000 Sq. Ft. • Coverage Areas: Maintenance Production Logistics (Fork Lift Computers) • Emergency Device
Tracking
• Surveyed at 2.4-GHz 802.11b/g • 2 Cisco 4400 Series Wireless
Controllers • 52 Cisco Aironet 1240 Series
Access Points Mounted very high inside and outside of the plant
• Cisco 7921 Wireless Phones • Omni Directional High Gain
Antennas • Added 5-GHz and 802.11a No major improvement
• Large Steel Building 500,000 Square Feet Two 7 Story Bay Open Steel Structures Numerous Multi-level Spaces Large Equipment
Air • Metal Powder in the Air • Large Metal Racks with 2 Ton Bags of
Metal Powder • Magnetic Separator • Overhead Cranes • Tunnels, Small Enclosed Spaces • Electric Arc Furnace • Poured Concrete Walls with Rebar
• Multipath • Reflection • Shadowing • One way calling
Area) • Loss of service (Leaving Service Area) • Antenna Patterns missing coverage area • AP’s improperly placed • Wrong Antennas
• Interference from plant equipment • Other wireles wireless s networks networks (Frien (Friendly dly Rogues) Rogues)
• Cisco Advanced Services Survey for Harsh Environments
• 802.11a/g/n 2.4GHz (primary) and 5GHz • 3 qty 5505 Series Controllers
• Cisco WCS (Wireless Control System)
for Management • MIMO technology
• 90 Cisco Aironet 3500 Series APs with
CleanAir technology • 50 Cisco 7925G-EX wireless phones
• Use Cisco Aironet 3500 Series Access
Points with CleanAir Technology and Wireless Controllers • Use small Di-pole and Directional
Antennas to ensure proper coverage • Lower placement of AP’s • RRM (Radio Resource Management)
• Locates Interference with Zone
of Impact • Air Quality Results • Map Visualization with WCS
• Persistent Device Avoidance
• Self Healing Networks • ClientLink and MIMO
802.11a/g devices work better
• Helps troubleshooting
performance problems in real-time Tracks ks intermittent and • Trac past problems • Reporting on usage and
interference trends • Reduces man hours to
manage and troubleshoot wireless problems
• Outdoor Survey • Upgrading from WCS to
Prime NCS Aironet 1500 Series • Cisco Aironet Mesh Access Points
• Survey • WCS • AP Placement (Lower) • AP Selection • Antenna selection and mounting
angles
Thank you.
