High Density & High Availability in Wireless Deployment

Transcription

1 Fast Innovation requires Fast IT High Density & High Availability in Wireless Deployment MinSe Kim, Sr. Technical Marketing Engineer, Cisco Systems 1

2 Agenda WiFi Operation Today WLAN RF Design Fundamental Physical AP Placement Tips Configuration Best Practices Wired-Wireless Integration for HD WiFi 3 WiFi operation Today 2

3 Why High Density Wi-Fi? Wireless has become the preferred access technology -- and in many cases the only practical one The need for high density started with stadiums and auditoriums but has reached every network The explosion of smart devices and increasing connection counts per seat are everywhere Application demands are increasing Even with advances - wireless is still a shared half-duplex medium and requires efficient use to succeed. 2 to 3 devices per user What are Some Typical Challenges? Interference from other WiFi networks in the venue Interference from non-wifi systems operating in the same band Co-channel interference: Many APs in the venue, but effectively no more capacity Clients operating at low data rates (ex b) pull down the performance of the network Clients mistakenly choose a 2.4 GHz radio (louder signal) instead of 5 GHz (less load) Sticky Clients: Clients mistakenly stay on the same AP, even when person has moved from one end of the venue to another Limitations on AP installable location. Hard to put APs where you want them Probe storms: 2.4 GHz clients probe on all 11 overlapping channels 3

4 Signal Quality Inevitable Interference from neighboring WiFi or from unknown sources Interference from Neighboring WiFi is impacting user experience Interference from Non-WiFi is also increasing 5GHz adoption is progressing but still less then 50% Neighboring AP is going louder and louder everyday Signal Quality Issue Higher Tx Power means better coverage? Not always. Balanced link (make LinkBudget between UL and DL to be as closest as possible) provides most reliable performance WiFi coverage characteristic is determined by uplink link budget (Handset dependent) Max. Tx Power per antenna Number of Tx chain Number of Rx chain Ant. Gain (Omni) # of Tx:Rx antenna Cisco AP dbm 3 TX 4 RX 4 dbm 3:4 Cisco AP dbm 4 TX 4 RX 4/7 dbm 4:4 iphone 5 20 dbm 1 TX 1 TX -1.5 dbm 1:1 4

5 Balanced Link budget for Better Quality, Loadbalanced link Differences in Rx Sensitivity and Tx Power makes client to deem out of coverage AP as closer then what it actually located. Hence, Client roaming is not occurred, User exposed many problem Load Balancing doesn t work Roaming involves service outage. Increasing Packet Loss Network throughout drop -84 dbm, Seriously?! Come on- You need to roam! 30 dbm EIRP from AP AP s perspective on iphone-a AP1 coverage RSSI for Client-1 : -84 dbm -76 dbm! RSSI s still okay!..i ll stay here 22.5d Bm EIRPClient-1 from iphone RSSI for AP-1 : -73 dbm AP n Myth What we hear from the industry 802.1n will deliver 300Mbps, 450Mbps, 600Mbps 900 Mbps So Can WLC get chocked up as WLC will become bottleneck? Most of n supported Mobile device Supports 20Mhz, Long Guard Interval Single Tx / Rx Max Datarate = 65Mbps 98% of mobile device until Mid % Datarate increase from a/g Oversubscription is between downlink-uplink is typical in wired design (100Mbps x 24 : 1Gbps 24 Gbps x 20 : 2-20Gpbs) Required Network performance is application driven, not device driven 5

6 Mobile device WiFi Max Data rate Galaxy S Galaxy S4 iphone Samsung Galaxy S3 iphone 1 iphone 3G iphone 3GS iphone 4 iphone 4s iphone 5 iphone 5s iphone 6 Client Association Storm In Subway Station, hundreds to thousand people can flood in/out Delay should be minimized, and immediate IP address assignment should happen Cisco s Association rate (CPS) 8500 WiSM2 vwlc Open WPA2 (EAP) Cisco DHCP Server(CNR) can assign 47,000 IP address in a seconds 6

7 Link Reliability during the roam Roaming must includes handoff and message exchange between AP-to- Client, between AP-to-AP Cisco Device support Caveats OKC Yes Windows Limited to few Android device Sticky Key Caching (802.11i) Yes Apple, Android Scalability issue r Yes Apple ios 6.0+ Can cause Legacy interoperability CCKM Yes CCX compatible device (eg. Samsung Galaxy S3) Limited support on Mobile device Average Roaming delay 0.5 sec 0.5 sec 0.1 sec 0.1 sec WLAN RF Design Fundamental 7

8 Channel Utilization What Made the Difference? 60% Before 5% After 15 Maximize the Spectrum Leveraging PHY Rate Tuning Size your cells to allow elimination of low rates (i.e., <12mbps) Eliminate 11b rates Recommend NOT disabling any MCS rates due to interoperability issues with some clients Disabling MCS rates, especially 0-7, can cause significant client issues 16 8

9 Cell Size Higher Power Larger Coverage Higher power does not always mean higher SNR Assuming 10% PER Speed Required SNR AP Sensitivity This for data, for voice, add 25 db to SNR 17 Cell Size Depends on Protocol and Rates Data rates decrease with the increase of distance from the radio source and client power will increase Individual throughput (performance) varies with the number of users Performance degrades with radio interference from other sources Critical deployment design goal is to achieve high data rate at cell boundary High signal AND low noise 18 9

10 2.4-GHz Network Design Conclusion: try to design small cells, with clever overlap 19 Designing for Efficient RF Relationships AP to Client How clients hear AP s Client to AP How AP s hear clients AP to AP How AP s hear each other 20 10

11 Channel Coverage Sizing Recommendations Coverage must be designed for your Client Devices Not all clients are created equal!!! 1. Live call test with the actual client to determine its coverage Removing legacy DSSS data rates and slower OFDM data rates from the WLC configuration equals: 1. Less Co-Channel Interference 2. Better throughput in the cell 3. More usage of ClientLink and MRC 4. Smaller coverage cells Smaller Coverage Cell Sizes equals: 1. More cells in a given coverage area 2. More cells equals more call with better voice and video quality 21 Physical AP Placement Tips 11

12 AP Mounting Orientation Incorrect AP Orientation Correct AP Orientation Best Practice Place APs pointing down for APs with internal antenna Internal antenna version Access Points Designed for Horizontal Mounting Internal antenna versions of Access Points work best when mounted horizontally on the ceiling 12

13 AP Antenna Vertical coverage Ceiling RF Radiation is focused to downward direction Installation use case To maximize AP s performance, AP installation location is highly recommended at ceiling mount as exposed. If customer must install AP inside ceiling, customer can consider external antenna model. External Antenna with AP inside ceiling 13

14 Where is the best location to place AP? Bad AP Placement : AP around corner At A the phone is connected to AP 1 A 1 B C 3 2 At B the phone has AP 2 in the neighbor list, AP 3 has not yet been scanned due to the RF shadow caused by the elevator bank At C the phone needs to roam, but AP 2 is the only AP in the neighbor list The phone then needs to rescan and connect to AP B 54 Mbps is sent in 3.7 μs 200 B 24 Mbps is sent in 8.3 μs Rate shifting from 54 Mbps to 24 Mbps can waste 1100 μs 28 14

15 Good AP Placement AP on Intersection A 1 B 2 C At point A the phone is connected to AP 1 At point B the phone has AP 2 in the neighbor list as it was able to scan it while moving down the hall At point C the phone needs to roam and successfully selects AP 2 3 The phone has sufficient time to scan for AP 3 ahead of time 29 Avoid Reflections Highly reflective environments Multipath distortion/fade is a consideration Legacy SISO technologies (802.11a/b/g) are most prone n improvements with MIMO Devices are susceptible Things that reflect RF Irregular metal surfaces Large glass enclosures/walls Lots of polished stone 30 15

16 AP Placement in Hallways Incorrect AP Placement Correct AP Placement Best Practice Place APs within the Room AP Placement in Multi-story Building Incorrect AP Placement Correct AP Placement Best Practice Place APs in Zig-Zag on Alternate Floors 16

17 WiFi Best Practices General RF Recommendations Lower 2.4 speeds not turned off -1,2,5.5,6,9 Meg Enable 2.4 GHz and 5 GHz bands Guest & Admin on separate SSIDs and VLANs n throughout most of the property ac in spaces with high device density 17

18 Wired-Wireless Integration for HD WiFi One Network: Wireless Deployment Modes Autonomous FlexConnect Centralized Converged Access WAN Standalone APs Traffic Distributed at AP Traffic Centralized at Controller Traffic Distributed at Switch Target Positioning Purchase Decision Benefit Key considerations Small Wireless Network Branch Campus Branch and Campus Wireless only Wireless only Wireless only Wired and Wireless Simple and cost-effective Enterprise Class AP quality Provides Bridge functionality Limited features First step to Controller based Highly scalable for large number of branches No controller at branch L2 roaming only Branch with WAN bw and latency requirements Most feature rich solution Wireless Traffic visibility at the controller Top Performance and Scalability Wired & Wireless common operations One Enforcement Point One OS (IOS) Traffic visibility at every network layer Performance optimized for 11ac Access layer refresh (3650/3850) 18

19 Campus Design: Centralized, Controller-based Components Wireless LAN controllers Aironet Access Points Management (Prime Infrastructure) Mobility Service Engine (MSE) Principles Overlay Architecture Based on AireOS software AP must have CAPWAP connectivity with WLC Configuration downloaded to AP by WLC All Wi-Fi traffic is forwarded to the WLC MSE Campus Network Cisco Prime Infrastructure Wireless LAN Controller Aironet Access Point Converged Access Deployment Overview Mobility Domain MO ISE PI Mobility Group MC MC Sub-Domain #1 Sub-Domain #2 SPG SPG MA MA MA MA MA MA 19

20 Working towards architectural integration Cisco ONE Architecture ISE, Prime, APIC Cisco Enterprise Aironet Catalyst ISR / ASA Cisco Cloud Managed MR MS MX Flexibility Simplicity Cloud and on-premise deployment configurations Optimized for Ease of Management Hybrid Optimized for Flexibility and Control Cisco Enterprise Core / Datacenter Cisco Enterprise Campus & WAN Cisco Cloud Managed Cisco Cloud Managed Edge Cisco Cloud Managed Branch Cisco Enterprise Mid-Market Business Enterprise and Mid-Market Business 20

21 HD Wi-Fi -- Best Practices Solid RF Design Constrain RF Directional Antennas, Down-Tilt Good RF Layout/Design: Channels, Tx Power Eliminate Interference Rogues and Non-Wi-Fi Interference Basic Tuning Minimize SSIDs Disable Low Data Rates Helps with Sticky Clients, Improves capacity Band Select Push dual-band clients to 5 GHz RF Profiles Advanced Rx-SOP Tuning Greatly improves capacity by reducing cochannel impact Also reduces sticky clients Optimized Multicast Video 21

22 Backup Slides Below or Above Ceiling? AP Inside Ceiling Mount WAP Lot of interferences AP s RRM tends to reduce Tx power as it see AP LoS WAP When Signal went through ceiling tile, Signal level is lowered from attenuation Automatic RF Power Control (TPC) can give less power then required Higher Co-Channel Interference between AP-to-AP Reduced Speed, Lowered Location accuracy Exposed Ceiling Mount RF Signal from AP s back panel is reduced from ceiling s attenuation. No impact on performance WAP WAP AP s RF coverage is as site surveyed. Coverage & performance is getting mostly close its intended one. No attenuation 22

23 Comparisons per AP s installed area Above Ceiling Performance Lower Higher Interference between APs Higher Below ceiling lower RF Signal Strength Reduced to 50% (3dB) Maintain RF coverage and strength as it s planned Custom enclosure and Locker Possible Possible Location Accuracy Lower High Maintenance Higher Lower Installation Cost Higher ( Possibly, separate bracket or enclosure) Lower (Mount kit is included w/ 0$) 23