Wireless LAN Basics for K-12
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WIRELESS LAN BASICS FOR K-12 RIDING THE WAVE 2016 #RTWGIMLI
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Transcript of Wireless LAN Basics for K-12
WIRELESS LAN BASICS FOR K-12
RIDING THE WAVE 2016 #RTWGIMLI
‣ About me
‣ RF Theory
‣ 802.11 Arbitration
‣ Network Planning and Design
‣ Site Survey Best Practices
‣ Suggested Configurations
‣ Troubleshooting Tips and Tools
‣ Education and Professional Development
AGENDA
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
#RTWGIMLI
ABOUT ME
▸ Steve McKim
▸ ICT Technician @ Park West School Division
▸ Independent Consultant - greatwhitewifi.com
▸ @alfmckim
▸ CET, CWNA, CWAP, ACWA
▸ Delegate at Mobility Field Day 1 - techfieldday.com/events/mfd1
▸ Next WiFi Rockstar Contest winner - thenextwifirockstar.com
WIRELESS LAN BASICS FOR K-12
“Wi-Fi is not an extension of networking. It is an entirely new medium and should be learned as such.”
-Ryan Adzima (@radzima)
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
TAKEAWAYS
“WLAN basics are, WLANs aren’t basic!”
-Jimmy Seaman (@jimmyseaman)
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - DECIBEL (dB)
▸ dB is a logarithmic unit
▸ Expresses a ratio
▸ dB is relative
▸ dBm and dBW are absolutes
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - ANTENNA GAIN
▸ A measure of antenna directivity
▸ More gain means higher directivity
▸ Measured in dBi or dBd
▸ Typical AP internal antenna is 3-6 dBi omni
▸ Relative value
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - ANTENNA PATTERNS
▸ Omnidirectional
▸ Patch/directional
▸ Highly directional
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - MILLIWATT TO dBm CONVERSION
0 dBm = 1 mW
3 dBm = 2 mW
6 dBm = 4 mW
9 dBm = 8 mW
10 dBm = 10 mW
12 dBm = 16 mW
13 dBm = 20 mW
15 dBm = 32 mW
16 dBm = 40 mW
18 dBm = 64 mW
20 dBm = 100 mW
30 dBm = 1 W
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - RULE OF 3’S AND 10’S‣ To double mW, add 3 dB
‣ To multiply mW by 10, add 10 dB
‣ Industry Canada allows max transmit power of 1 W, max EIRP of 4 W (RSS-247).
10 mW = 10 dBm
20 mW =
2 mW = 3 dBm
4 mW =
1 mW = 0 dBm
10 mW =
5 mW = 7 dBm
50 mW =
30 dBm 36 dBm
6 dBm 13 dBm
10 dBm 17 dBm
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - 6 DB RULE
▸ If you increase radiated power by 6 dB, the coverage radius will double.
▸ If you double the distance between a transmitter and receiver, the received signal level will drop by 6 dB.
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - SIGNAL STRENGTH
▸ Received signal amplitude
▸ Measured in dBm, always a negative number
▸ The higher (closer to 0), the better
▸ One of many key metrics for WLAN performance
▸ Vendors interpret RSSI differently
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - SIGNAL TO NOISE RATIO
▸ Measured in dB
▸ Difference between rx signal level and measured noise floor
▸ More important than RSSI
Source: https://support.metageek.com/hc/en-us/articles/201626114-Calculating-Approximate-SNR-with-Chanalyzer-Wi-Spy
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - 802.11 CHANNELS IN CANADA
▸ 2.4 GHz ISM band (2400-2483.5 MHz)
▸ 5 GHz made up of
▸ UNII-1 (5150-5250 MHz)
▸ UNII-2 (5250-5350 MHz)
▸ UNII-2e (5470-5725 MHz)
▸ UNII-3 (5725-5850 MHz)
▸ IC RSS-247
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - 2.4 GHZ CHANNELS
▸ 20 MHz only!
▸ 1, 6, 11 only!
Source: http://www.emperorwifi.com/2015/08/an-explanation-of-channel-and-transmit.html
Source: http://wifinigel.blogspot.ca/2013/02/adjacent-channel-interference.html
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - 5 GHZ CHANNELS
▸ MAYBE 40 MHz…Never bigger
▸ Use DFS with caution and testing
▸ Know client makeup and capabilities - clients.mikealbano.com
Source: http://www.revolutionwifi.net/revolutionwifi/2013/03/80211ac-channel-planning.html
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - MODULATION AND CODING SCHEMES
▸ MCS dictates throughput
▸ Depends on SNR
▸ Determined by channel size, spatial streams, coding rate
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - MODULATION AND CODING SCHEMES
Source: http://www.wlanpros.com/mcs-index-802-11n-802-11ac-chart-3/
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - MODULATION AND CODING SCHEMES
Source: http://www.wlanpros.com/wp-content/uploads/2015/06/Revolution-Wi-FI-MCS-to-SNR-Single-Page.pdf
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
RF THEORY - MODULATION AND CODING SCHEMES
Source: http://www.wlanpros.com/wp-content/uploads/2015/06/Revolution-Wi-FI-MCS-to-SNR-Single-Page.pdf
802.11 ARBITRATION
▸ Clear Channel Assessment (CCA) aka Physical Carrier Sense
▸ Carrier Sense and Energy Detect
▸ Virtual Carrier Sense
▸ NAV Timer
▸ Inter-frame Space (SIFS, DIFS, AIFS, RIFS, EIFS)
▸ Contention Window, Random Back-off Timer and time slots
▸ White Paper by Marcus Burton
▸ https://www.cwnp.com/uploads/802-11_arbitration.pdf
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
802.11 ARBITRATION
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
https://www.cwnp.com/uploads/802-11_arbitration.pdf
NETWORK PLANNING AND DESIGN
▸ WLAN Life Cycle
▸ Design is an iterative process
▸ Coverage vs capacity
▸ Know your requirements
▸ Use the right tools for the job
▸ Design process
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
Source: Rowell Dionicio (@rowelldionicio, packet6.com, cleartosend.net)
WLAN DESIGN PROCESS
▸ Gather requirements
▸ Get a scaled floor plan
▸ Measure wall attenuation
▸ Predictive design
▸ AP-on-a-stick (maybe)
▸ Deploy
▸ Validate (ALWAYS!)
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
Source: https://gcatewifi.wordpress.com/2016/02/18/wlan-planning-part-1-the-wlan-cart/
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
PLANNING TOOLS - CAPACITY PLANNER
▸ http://www.revolutionwifi.net/capacity-planner/
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
PLANNING TOOLS - CAPACITY PLANNER
▸ http://www.revolutionwifi.net/capacity-planner/
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
PLANNING TOOLS - SSID OVERHEAD CALCULATOR▸ https://itunes.apple.com/us/app/revolution-wi-fi-ssid-overhead/id1041231876
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
PLANNING TOOLS - DESIGN/SURVEY TOOL
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
PLANNING TOOLS - DESIGN/SURVEY TOOL
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
PLANNING TOOLS - DESIGN/SURVEY TOOL
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
PLANNING TOOLS - DESIGN/SURVEY TOOL
CONFIG TIPS
▸ Disable 802.11b data rates
▸ Consider disabling lower OFDM data rates
▸ Use as few SSIDs as possible to reduce management overhead
▸ AP transmit power matched or lower than clients
▸ Disable 2.4 GHz radios if necessary to reduce CCI
▸ 40 MHz channels in 5 GHz if possible
▸ What does your vendor say?
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
TROUBLESHOOTING TIPS
▸ Ask questions - when, where, who?
▸ Move up the OSI stack - 70% of problems are at physical layer
▸ Interference, client problems, PoE
▸ Discovery tools give high level picture of environment
▸ Spectrum Analysis
▸ Frame Analysis
▸ David Coleman - WLAN Troubleshooting, WLPC2016
▸ https://vimeo.com/album/3831972/video/157361943
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
DISCOVERY TOOLS
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
SPECTRUM ANALYSIS
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
SPECTRUM ANALYSIS
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
FRAME ANALYSIS
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
FRAME ANALYSIS
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
EDUCATION AND PROFESSIONAL DEVELOPMENT
▸ Certifications
▸ CWNP vendor neutral training - cwnp.com
▸ Vendor training (CCNA, AWCA, ACMA, etc)
▸ Online Videos - separate marketing from technical info
▸ ekahau.com/training
▸ cwnp.com/freeresources/it-webinars/
▸ vimeo.com/keithrparsons/collections
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
EDUCATION AND PROFESSIONAL DEVELOPMENT
▸ Podcasts
▸ Clear to Send - cleartosend.net
▸ WiFi for Beginners - wififorbeginners.com
▸ Whiskey and Wireless - whiskeyandwireless.com
▸ No Strings Attached - nsashow.com
▸ Blogs
▸ revolutionwifi.net
▸ my80211.com
▸ wifinigel.blogspot.ca
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
EDUCATION AND PROFESSIONAL DEVELOPMENT
▸ @alfmckim
▸ #WIFIQ
▸ Community
▸ wifiacademy.net
#RTWGIMLIWIRELESS LAN BASICS FOR K-12
