Spectrum management best practices in a Gigabit wireless world

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With the introduction of 802.11ac the news is full of the potential for Gigabit networking.  Very few of us will have the luxury of running a network that strictly supports 802.11ac and that means a mixed environment for most of us.  Get the facts on what 802.11ac means to you, how to evaluate using 20, 40, 80 or 160 Mhz OBSS/Channels.  How does RRM's DCA handle a mixed environment and what performance considerations do you need to consider to make decisions that make the best of the spectrum you have today and in the future.  What is in the future for our spectrum?  To learn more please visit our website here: http://www.cisco.com/ca/

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Spectrum management best practices in a Gigabit wireless world

  1. 1. Advanced RF properties at your disposal to improve Enterprise WLAN deployments and spectrum quality BRKEWN-3010 Jim Florwick Platform TME – Wireless CiscoLive 2014 Milan
  2. 2. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public House Keeping Notes – Wednesday April 16, 2014 Thank you for attending Cisco Connect Toronto 2014, here are a few housekeeping notes to ensure we all enjoy the session today.  Please ensure your cellphones are set on silent to ensure no one is disturbed during the session  I will take questions during the session, but may ask that your hold it if we’re ahead of the material 2
  3. 3. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public What We’re Going to Cover 3  How important is the RF? – The Physical Layer – we will focus exclusively on the physical  Site Survey – When was the last time a survey was done?  Tools – A word about tools – Prime Planner, Ekahau, AirMagnet, Spectrum analysis  What are your Priorities?  RRM – RF Grouping – Dynamic Channel Assignment  Tuning – RRM, Client Link, Band Select, HDX – RX_SOP/SmartRoam, RF Profiles  Summary
  4. 4. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public By The End of This Session You should understand – Where to get information – How to evaluate that information and use it – Understand what tools and techniques are available to solve specific issues – Use the information presented to create an action plan for change – Improve your networks capacity and your users lives 4
  5. 5. Wireless Trends- What’s Your Goal?
  6. 6. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public 1999 Wireless Evolution From Best Effort to Mission Critical Hotspot System Management Scalable Performance 802.11n/OBSS Self Healing & Optimizing 802.11acGigabit Wireless HS2.0 HDX 1999 2005 2007 2010 2013
  7. 7. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public The changing RF landscape 7 Protocol Date Characteristics Spatial Steams 20 MHz Channels 802.11 1997 1,2 Mbps, infra Red, spread and DSSS, 802.11FH 2.4 GHz 1 1 802.11b 1999 1,2,5.5,11 Mbps, DSSS 2.4 GHz 1 1 802.11a 1999 6,9,12,18,36,48,54 Mbps – OFDM – 5 Ghz 1 1 802.11g 2003 6,9,12,18,36,48,54 Mbps OFDM 2.4 GHz 1 1 802.11n 2005 MCS 1-15-23 1-3 SS, OFDM, 20,40 MHz, 2.4 and 5 GHz 1-3 1-2 802.11ac 2012 1-8 SS MCS 1-9, OFDM, 20-40-80-160 MHz, 5 GHz 1-8 1-8
  8. 8. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  2013 is the first year we’ve seen higher 5 GHz adoption rates  CiscoLive and Mobile World Congress - high tech shows – SuperBowl different crowd 98.5% 802.11n 0.1 38 40 55 29 50 60 99 62 60 45 71 50 40 0 20 40 60 80 100 120 5 GHz 2.4 GHz 98% 802.11n for 2012 and 2013!
  9. 9. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Key Reports – Cisco Prime  Clean Air –  How much of your spectrum is being used by NON Wi-Fi devices?  Client –  What protocols are your client using?  Unique Client Summary – should be a frequent reference  Device –  Channel Utilization – how much spectrum do you have?  Security  Are Rogue Access points using your spectrum?  Which AP’s hear them – how loud? The above reports will tell you what/who is using your spectrum, how efficiently you are using your spectrum and how much you have left 9
  10. 10. Deploying with Spectrum in Mind
  11. 11. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Deploying with Spectrum in Mind  Role of site survey is as important as ever—but has evolved  Evaluate the existing application requirements, available spectrum and Client types/mix  Focus should be on fixed infrastructure – AP placement – Density is important = capacity – Protocols supported – Rates supported – Interference sources  Mitigating issues  Planning tools Designing for Sustainable Spectrum Management
  12. 12. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public About Site Surveys  When was the last time you did a site survey? – What where the design goals when that survey was done? – Coverage or Capacity model? – Client/AP types and technology?  Technologies Change – how many devices/clients where on your network the last time you did a survey  What are your design Priorities? What where they when you last did a survey?  You don’t know what you don’t know and not all 802.11 technologies are complimentary – air time rules 12
  13. 13. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public A Word About Tools  What you use is less important than how you use it –  Internal vs external adapters – Internal adapters – even the same model will have different antenna arays and placement for different model laptops – External adapters – can be moved with the application – and provide consistent results – regardless of the platform used  Use the same Tool to compare results!  Recheck results from a known environment with version updates  Free Tools – Nothing is Free How to compare Apples to Apples
  14. 14. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public What has not changed? 802.11 and Duty Cycle – Channel Utilization – Air Time  802.11 error recovery is limited - Still – Retransmit a packet – Rate shift  Duty Cycle of RF is logarithmically proportionate to Channel Utilization  Channel Utilization is Capacity  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  At a minimum – you have more users on your network this year than you did last year – and a lot more than you had 5 years ago….
  15. 15. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public How does Interference impact Wi-Fi? Separating the FUD from the Fact’s  802.11a/b/g/n - CSMA/CA or LBT (listen Before Talk)  Collision Avoidance – 802.11 very very polite – by design – CCA – Collisions – SNR  CCA – Clear Channel Assessment – ED – quick – low power - prone to false positives – Preamble – takes time – power – less prone to false  CCA threshold for 802.11b/g is -65 dBm  CCA for 802.11a is different -65 dBm ED, if true then 20 dB lower for Preamble interrogation needs to be processed -85 dBm
  16. 16. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public CCA Blocked or High 802.11n traffic Video Signal Video Camera Duty Cycle 90-100%
  17. 17. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public How does Interference impact Wi-Fi? Separating the FUD from the Fact’s  Collisions - Non Wi-Fi devices do not participate in our CA mechanism – they have their own  No respect for Wi-Fi – results in: – Corrupted packets – Increased retransmissions – Increased Duty Cycle – Less available bandwidth  SNR – Signal to Noise ratio High SNR Low SNR
  18. 18. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public 802.11 and Duty Cycle – Channel Utilization  802.11 error recovery is limited – Retransmit a packet – Rate shift  Duty Cycle of interference is logarithmically 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
  19. 19. For a deep dive on CleanAir and it’s best in class features see – BRKEWN-3010 Orlando, Fl. June 2013 • Available on CiscoLive365
  20. 20. RRM – Radio Resource Management
  21. 21. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RRM—Radio Resource Management  What are RRM’s objectives? – To dynamically balance the RF infrastructure and mitigate changes – Monitor and maintain coverage for all clients – Manage Spectrum Efficiency so as to maintain the optimal throughput under changing conditions  What RRM does not do – Substitute for a site survey – Correct an incorrectly architected network – Manufacture spectrum
  22. 22. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RRM Monitors the RF Group  Continuously monitors dynamic changes in environment – Collection of statistics and metrics used by DCA, TPC, and CHDM – Provides assessment of the overall “RF health” of the network  Stats/metrics include: – Noise (e.g., radar, Bluetooth devices, microwave ovens) – Interference (802.11—rogue APs) – Signal – (our AP’s) – Load
  23. 23. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public How Does RRM Do This?  DCA—Dynamic Channel Assignment –Each AP radio gets a transmit channel assigned to it –Changes in “air quality” are monitored, AP channel assignment changed when deemed appropriate (based on DCA cost function)  TPC—Transmit Power Control –Tx Power assignment based on radio to radio pathloss –TPC is in charge of reducing Tx on some APs— but may also increase Tx by defaulting back to power level higher than the current Tx level  CHDM—Coverage Hole Detection and Mitigation –Detecting clients in coverage holes –Deciding on Tx adjustment (typically Tx increase) on certain APs based on (in)adequacy of estimated downlink client coverage
  24. 24. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RF Grouping Neighbor Messages = OTA – Over The Air - RF analysis  Neighbor AP messages are sent every 60 seconds at highest power and lowest supported data rate  Neighbor Messages are used by receiving APs and their WLCs to determine how to create inter and Intra-WLC RF Groups and Physical RF Neighborhoods  Each AP listens for other AP’s neighbor messages – and if it’s RF Group name matches – the message is forwarded to it’s controller and ultimately to the RF Group leader  A list is maintained for each AP in the RF Group of who heard his neighbor messages and how loud Neighbor messages are sent from each AP to multicast address 01:0B:85:00:00:00
  25. 25. For a deep dive on the concepts of grouping, Neighbor Discovery, and collection of off channel metrics used in RRM algorithm’s – please read – Radio Resource Management (RRM) RF Grouping • Part of the 7.4 RRM Design Guide presently under revision
  26. 26. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RRM—DCA— Dynamic Channel Assignment Ensures that available RF spectrum is utilized well across frequencies/channels Best network throughput is achieved without sacrificing stability or AP availability to clients 34 RF Channel “64” RF Channel “44” RF Channel “100” Analyzes and Optimizes Channel assignments Coordinates 20,40, and 80 MHz OBSS assignments Using OTA measurements What It Does
  27. 27. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  Who calculates DCA – It runs on the RF Group Leader WLC – Decisions on channel assignment change made on a per AP, per radio basis  DCA manages channel assignments to each AP – Assigns channels to radios – Changes the existing assignment on some radios, if appropriate  What criterion is evaluated: – RSSI-based Cost Function that captures overall interference (including non-802.11 noise) on a per channel basis Monitor=>Access Points=>Detail
  28. 28. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  DCA represents each channel using essentially a compound signal to noise ratio. This is called a cost metric or CM.  Contributions to this metric are – Signal – Our AP’s TX and RX neighbor – Noise – Non Wi-Fi interference – Interference – Managed and unmanaged rogues – Load – Cisco Channel Utilization  You can manipulate what you want to contribute to the metric – by default Signal, Noise, and Interference are selected. Wireless=>802.11a/b=>RRM=>DCA
  29. 29. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public • Defaults are generally best • Avoid Foreign AP Interference If enabled – places a higher penalty on rogue devices Is to encourage DCA to work around the neighboring AP Encourages good neighbor borders Can cause a lot of channel changes if enabled with a lot of transient rogue devices – disable if this is the case • Load – disabled. This accounts for Cisco AP load only. Can cause a lot of channel changes in a heavily used network. Wireless=>802.11a/b=>RRM=>DCA
  30. 30. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  DCA evaluates the Cost Metric to determine optimal channels for the network  The user defined threshold – DCA Sensitivity Threshold – allows customization of the algorithm  The threshold is a Hysteresis to dampen DCA function  If sensitivity is medium for 2.4 GHz then in order for a channel change to be made the new channel must be 10 dB better than the current channel or no change will occur. Version Band Low Medium High 6.0 + 2.4 GHz 5 dB 10 dB 20 dB 5 GHz 5 dB 15 dB 20 dB
  31. 31. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public DCA Example  What changes first is the CPCI selection process, randomization prevents pinning –  For a given CPCI, calculations permit changing first hop channels  Second hop channels considered  Solution is submitted to NCCF  CPCI and 1st neighbors are removed from the CPCI list  Next randomized CPCI is selected
  32. 32. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  Selection of 20 MHz – all AP’s set to 20 MHz  Selection of 40 MHz – All 40 MHz capable AP’s set to 40 MHz – 20 MHz only AP’s will remain 20 MHz  Selection to 80 MHz – all 80 MHz capable AP’s set to 80 MHz – Others – 802.11n at 40 MHz, and 802.11a at 20 MHz Wireless=>802.11a/b=>RRM=>DCA
  33. 33. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  Using the example of an 80 MHz OBSS – (Overlapping BSS)  AP-AC wins contention on my primary channel and will send data on that channel and 3 other bonded channels.  The VHT header tells all 802.11AC stations that I’m using an 80 MHz OBSS and even tells what 20 MHz sub channels it’s using  But What of the lowly 802.11a station, or the 802.11n (HT) station who don’t speak 802.11ac and it’s fancy VHT language?
  34. 34. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  Never Fear – LBT (Listen before Talk) to the rescue – CCA! (Clear Carrier Assessment)  CCA thresholds where adjusted in the 802.11ac specification to allow Overlapping BSS and IBSS stations coexist by adjusting the contention requirements for Sub Channels  In the table above – you can see that all 3 protocols have equal contention on the primary.  Any primary operating within a secondary 20 or 40 will loose contention  Any secondary 20 operating in a secondary 40 will win contention over other secondary's! Protocol Primary Secondary 20 MHz Secondary 40 MHz 802.11a -82 dBm 802.11n -82 dBm -62 dBm (20 dB liberty) 802.11ac -82 dBm -72 dBm (10 dB liberty) -76 to -79 (3-6 dB liberty)
  35. 35. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  The 802.11AC specification allows for an RTS to be sent on all sub channels as an 802.11a frame, and expects a CTS if a primary channel is assigned to one of the sub channels – The specification says that RTS is optional, but CTS is mandatory – Will clients implement this? Even when the secondary40 channel is occupied by a transmission, an 80 MHz 11ac AP can select to transmit 40 MHz for the time being, thus the system still fully utilizes the channel. (The placement of the primary on which half of the secondary40 is no longer a critical concern.)
  36. 36. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  The level of constructive coexistence among OBSS’s is based on these criteria: – Fair channel access – Fairness between 11ac and 11ac is neutral  Fairness between 11ac and legacy (11n and 11a)  Number of hidden nodes decreases  Number of collision decreases  Overall performance and efficiency increases
  37. 37. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public In simulations and analysis, the general level of constructive coexistence decreases between two OBSSs in the order for these possible scenarios: 1. Primary and secondary20 channels mismatched 2. Primary channel on secondary40 or secondary 80 channels 3. Primary channels aligned
  38. 38. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public 49 Channel 40,44 802.11n 802.11ac Channel 48,52,40,44 -54 dBm 120 Mbps 50 Mbps -64 dBm 50 Mbps 120 Mbps -74 dBm 220 Mbps 10 Mbps -84 dBm 210 Mbps 90 Mbps
  39. 39. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public 50 Channel 48,52 802.11n 802.11ac Channel 48,52,40,44 -54 dBm 120 Mbps 50 Mbps -64 dBm 120 Mbps 50 Mbps -74 dBm 120 Mbps 50 Mbps -84 dBm 200 Mbps 90 Mbps
  40. 40. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public How does DCA keep track of all the other AP’s and the channels their using?  Remember the DCA cost Metric?  Add Bias to a given channels CM to reinforce good channel solutions  Bias values match the given 3 performance scenarios – B1, B2, B3 for our AP’s and R1, R2, R3 for rogues increasing the bias for lower coexistence values  For instance - Not using Channel 60, and the resulting CM for channel 60 is +128!
  41. 41. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  DCA will search for a 20, 40, 80 MHz solution for each AP – and only populate up to the AP’s capabilities  DCA channel Width settings determines the DCA mode  The AP Type determines the possible Channel Widths  DCA search’s for 20, then 40, then 80MHz channel widths and presents the solution as a grouping of cost metrics  Metrics for the same channel– can and will change for the channel width solution searched due to BIAS settings
  42. 42. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Airewave Director: metrics20 After Normaliz( 52, -81.68)( 56, -74.51)( 60, 128.00)( 64, -55.38) <snip> Airewave Director: metrics40 After Normaliz( 52, -78.53)( 56, -75.49)( 60, 128.00)( 64, -55.37) <snip> Airewave Director: metrics80 After Normaliz( 52, -59.23)( 56, -59.18)( 60, 127.98)( 64, -56.65) <snip> *RRM-MGR-5_0-GRP: Sep 23 15:59:38.556: 64:d9:89:42:29:50 <snip> Note – there are 3 similar but different answers - It is 3 different questions with 3 different set’s of rules. What determines Which answer is used? *RRM-MGR-5_0-GRP: Sep 23 15:59:38.551: 64:d9:89:42:29:50 Airewave Director RRM Chan Assignment Mode: 2 Lrad Capability: 2 DCA Channel Width: 2 0= 20 MHz 1 = 40 Mhz 2 = 80 Mhz
  43. 43. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  802.11ac and 80 MHz - lets see what this baby can do!  Likely already a full spectrum (the network was already there right?) – Using DFS channels already? – Already have 40 MHz assigned for 802.11n?  Likely DCA is at medium Sensitivity 10 dB Hysteresis – Changing Channel Width – is a major change – Expanding some channel Width’s to 80 Mhz and others to 40 Mhz is not trivial – Don’t limit the possible solutions to within 10 dB!
  44. 44. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public 5 GHz 20/40/80/160 MHz Channels 56 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 100 104 108 112 116 120 124 128 132 136 140 144 149 153 157 161 165 169 173 177 181 20 40 80 160 US Europe 20 40 80 160 Indi a 20 40 80 160 China Existing Channel New Channel UNII-2UNII-1 NEW! UNII-2 NEW! UNII-2 UNII-3 NEW! 5250 MHz 5350 MHz 5470 MHz 5725 MHz 5825 MHz 5925 MHz
  45. 45. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Feature Benefit 256-QAM 5/6 coding 30% faster – at any #ss Rate vs Range – significantly increased Faster speeds – further from the AP – faster overall cell – less airtime consumed 802.11ac – ONLY 5 Ghz Finally,Seriously, overdue…. Optional 802.11n Specifications Removed – discarded - junked Less implementation choices = less client variability Manufacturers already committed to implementation Many already delivering product
  46. 46. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public  Do you have spectrum available for 80 Mhz? – Evaluate by Regulatory  Do you use 40 MHz for 802.11n AP’s today? – If not – why not? – Does it make sense to use 80 MHz?  Plan the Implementation – and understand that this is a Major Change to your existing spectrum plan  Let DCA help you
  47. 47. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Best Practices for Implementing 802.11ac  Decide what Channel Width you will use  Implement new hardware –  Initialize DCA in Startup Mode – FROM the RF group Leader(s)  Remember – all of this is 5 GHz only! 7.3 and above – from the CLI - Config 802.11a/b channel global restart
  48. 48. Managing Efficiency
  49. 49. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RX Utilization 36 TX Utilization 7 Channel Utilization 96
  50. 50. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Channel Utilization – what is it?  Channel Utilization is the physical – and the logical Air Time consumed  It is – physical signal in the air above CCA  It is - the logical CW and NAV  It is – All RF in the air – ours as well as rogues – if it’s 802.11 and we hear it – it counts  It is the metric which represents the AP’s TX_op in the current channel  And- it represents the whole channel – not the AP’s utilization Root Cause for Channel Utilization must be isolated – Self Interference – SSID’s, Data Rates, AP isolation vs Density – control with Configuration – Non – Wi-Fi interference – possibly controllable – Rogue Devices/networks – configuration management
  51. 51. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Spectrum Is a Shared Finite Resource Understand Protocol Selection 802.11 b/g/a/n/ac and Duty Cycle—Important? Why? 75 0 500 1000 1500 2000 2500 3000 3500 6 12 36 54 130 173.3 300 540 64 Bytes 128 Bytes 256 Bytes 512 Bytes 1024 Bytes 2048 Bytes Data Bytes Time μS Data Rate - Mbps HT/VHT 40 3ss HT/VHT 20 2ss OFDM
  52. 52. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Every SSID Counts! 76  Each SSID requires a separate Beacon  Each SSID will advertise at the minimum mandatory data rate  Disabled – not available to a client  Supported – available to Existing associated client  Mandatory – Client must support to associate  Lowest mandatory rate is beacon rate  Highest mandatory rate is default mcast rate
  53. 53. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public AP-3700 – Supports Client Link 3.0 So why Client Link 3.0? • ClientLink’s beamforming capability unlike the standard improves the SNR for all clients including legacy clients. • Because this technology does not depend on any client-side hardware or software capabilities, it works with mixed-client networks seamlessly with 802.11ac and 802.11a/n clients that co- exist on the same Access Point • Standards based beamforming only works with .11ac clients and most of them do not support it at this time. A real “purpose built” AP is one that can support Cellular modules, Monitor radios, Wave-2 upgrades and can future protect your investment. We also didn’t “accidently” build the AP-3700 you might say “purpose built” includes ClientLink innovation, Spectrum Intelligence and Quality RF performance from the center of RF Excellence located in Richfield Ohio… Yes QUALITY DOES MATTER… 
  54. 54. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public 52.4 Optimized RF Utilization by Moving 5 GHz Capable Client Out of the Congested 2.4 GHz Channels 802.11? BandSelect Access Point Assisted 5 GHz Band Selection Dual-Band Client Radio 2.4/5GHz Discovery Probes Looking for AP Discovery Response Solution BandSelect directs clients to 5 GHz optimizing RF usage  Better usage of the higher capacity 5GHz band  Frees up 2.4 GHz for single band clients Challenge Dual-Band clients persistently connect to 2.4 GHz  2.4GHz may have 802.11b/g/n clients causing contention  2.4GHz is prone to interference
  55. 55. RF Profiles
  56. 56. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RF Profiles to Manage your RF Configurations  RF Profiles work in Conjunction with AP Groups (beginning in release 7.2)  You can create separate RF profiles for both 2.4 and 5 GHz  1 profile for each band (802.11a/802.11b) can be assigned to an AP group  What can be adjusted within a profile continues to expand with DCA expected in version 8.1  Today – 802.11 data rates – TPC Power Threshold and Min max Power settings – DCA (in 8.0!) – Coverage hole algorithm settings – High Density – HDX configurations RX_SOP, Client Limit, Mcast data rate – Client Distribution 82
  57. 57. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RF Profiles – RRM – Create  RF Tuning parameters can be applied through profiles assigned in AP groups  2 Profiles per AP group – 1 ea. 2.4 and 5 GHz  Profiles must be applied on ALL WLC’s from which AP’s will be assigned (same as AP Group)  Permits control of granular groups of AP’s  We love it… 83 Wireless=>RF Profiles
  58. 58. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Profiles : Granular Control 84 Data Rates Load Balancing TPC, DCA,Coverage Hole High Density
  59. 59. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Profiles – Applied Through AP Groups 87  Create Profiles  Create or edit AP Groups  Apply Profiles (2.4/5 Ghz) to AP groups  Assign AP’s
  60. 60. HDX – High Density Experience
  61. 61. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Bigger Cells, More Users Control Cell Size by Data Rate selection and RX tuning  The Cell is the unit of bandwidth  Manage the per user bandwidth by managing the size of the Cell  RF Profiles allows you to treat 2 groups of AP’s differently in order to tune the deployment to peak performance  Here are some additional tools to manage higher density encounters and win 90 167 PAX 40 PAX/per
  62. 62. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public When Coverage meets Capacity  You’ve eliminated several SSID’s  You’ve raised your data rates to fit the coverage areas  You’ve added AP’s to areas where additional coverage is needed…..  Channel Utilization won’t come down – and power is already at the lowest settings Welcome to High Client Density 91
  63. 63. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RX-SOP – Receive Start of Packet threshold 92  The AP has a threshold on each radio at which it logically honors a packet  Below this threshold – it is treated as noise  Above this threshold it is treated as Wi-Fi – and all the logical utilization that goes with that  When you start to add more channels for capacity – you will tune data rates and placement to decrease your transmit footprint  Use Antenna’s to focus your receive sensitivity  RX-SOP allows you to tune the receive cell size to match the Tx cell size  If you hear less – you will have less Channel Utilization
  64. 64. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RX-SOP – (Receive - Start of Packet) – What is it?  Receiver Start of Packet Detection Threshold (RX-SOP) determines the Wi-Fi signal level in dBm at which an AP radio will demodulate and decode a packet.  The higher the level, the less sensitive the radio is and the smaller the receiver cell size will be  By reducing the cell size we can affect every thing from the distribution of clients to our perception of channel utilization  This is for High Density designs – and requires knowledge of the behavior you want to support  A client needs to have someplace to go if you ignore it on the current cell WARNING – This setting is a brick wall – if you set it above where your clients are being heard – they will no longer be heard. Really.
  65. 65. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RX-SOP – Why Use It?  Reduce sensitivity to interference and noise – reduce Channel Utilization  It sharpens the cell edge – we will hear what we intend to cover  Caveats – – You can significantly reduce coverage – You can make it impossible for intended clients to associate or communicate with your AP  This feature is to be used in conjunction with a known design to solve a specific problems when you understand the coverage and usage of the network by the users  RX-SOP is available at the global level as well as in RF profiles – Strongly recommend applying only through profiles – to solve specific problems with HDX
  66. 66. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public RX-SOP configuration  Settings High, Medium, Low, Auto  Auto is default behavior, and leaves RX-SOP function linked to CCA threshold for automatic adjustment  Most networks can support a LOW setting and see improvement  This affects all packets seen at the receiver
  67. 67. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Optimized Roaming- help for clients that are not so smart…. 97 Optimized Roaming Disabled Optimized Roaming enabled
  68. 68. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Optimized Roaming  Sets a threshold RSSI value and or Minimum Data rate that a client will be sent a Disassociate  Developed to support Cellular Hand Off  Global configuration of 4 Parameters available – Enable/Disable – Interval (seconds) – Data Rate threshold – RSSI threshold configured through Data CHD  Trigger is Pre-Coverage hole event – set under CHDM config
  69. 69. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Optimized Roaming configuration  Enable/Disable – Global command  Interval = #seconds between checks at the Radio  Data Rate threshold-  Used in conjunction with RSSI threshold, if set is a gating function where both data rate and rssi must be true for action – default is disabled  RSSI threshold – set through data RSSI config in Coverage at the global level, and under RRM in RF Profile
  70. 70. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Optimized Roaming Logic Data RSSI Data Rate Result True Disable (default) Disassociate True False No Action True True Disassociate • Uses CHDM Data RSSI for trigger Alone – decision is based on RSSI seen at the radio • Combined with Data Rate – provides additional gate for action – and preserves CHDM Function • If Used with Client Low RSSI check, and the higher of the two values is used (with 6 dB hysteresis).
  71. 71. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Optimized Roaming & Low RSSI feature “WARNING”  Low RSSI check is a completely separate feature – and sets a low RSSI threshold which a client must be above to associate to the AP  Optimized Roaming has a 6 dB hysteresis built in to prevent thrashing  i.e. If Optimized roaming is set to -75, then to rejoin the AP the clients signal must improve to -69 dBm  The logic checks low RSSI – AND Optimized roaming before allowing a client to Join – and both must pass
  72. 72. For a deep dive on High Client Density design practices see BRKEWN-2019 RF design for the Mobile Device Explosion 2013 CL Orlando • Available on CiscoLive365
  73. 73. Summary
  74. 74. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Summary  Evaluating what the goal of your network is on a regular basis will enable you to make better design decisions  Good tools make and defend good decisions  Eliminating spectrum hogs should be first priority – strongly consider eliminating anything not OFDM all together (Legacy 802.11b)  Understand how RRM gathers information and makes it’s decisions  Allow RRM DCA to do it’s job – best practice to restart DCA after major changes to numbers, types, placements of AP’s  Not all your coverage zones have the same needs – use RF profiles! 104
  75. 75. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Links/References  Cisco 802.11n Design and Deployment Guidelines  Cisco High Density Wireless Lan Design Guide  Cisco Client Link White Paper  Client Link testing – Miercom  Client Link 2 Testing - Miercom Report Cisco 3600e/i 10 5
  76. 76. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public 106 Recommended Reading
  77. 77. Cisco and/or its affiliates. All rights reserved.Presentation_ID Cisco Public Complete Your Paper Session Evaluation – Wednesday April 16 Give us your feedback and you could win 1 of 2 fabulous prizes in a random draw. Complete and return your paper evaluation form to the Room Attendant at the end of the session. Winners will be announced today at the end of the session. You must be present to win! Please visit the Concierge desk to pick up your prize redemption slip. Visit them at BOOTH# 407

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