无线网络教学资料-r-ch3--pd_思科无线网络设计-ppt课件

1、 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID1无线网络设计及部署无线网络设计及部署 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID2模块内容模块内容 部署方法 部署需求 Protocol Comparison 企业无线网 Coverage & capacity 确定AP数量和位置 Z factor design Site Survey 验证无线网部署 2006 Ci

2、sco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID3Determine Deployment RequirementsAssessDetermine AP Count & PlacementDeployPlace Access PointsSurvey WLANVerifyPlanningToolsSite SurveyZ Factor部署方法部署方法 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentat

3、ion_ID4 Protocol requirements 802.11b/g 802.11a Client devices WNIC PDA Phone Client density Typical Peak Expected throughput 802.11b is typically 2 Mbps 802.11g is typically 11-14 Mbps 802.11g is typically 2-4 Mbps with 802.11b clients presents 802.11a is typically 11-14 Mbps部署需求部署需求容量思索容量思索 2006 C

4、isco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID5协议比较协议比较 The standards that must be supported by an enterprise WLAN are usually dictated by the devices that require support. Currently 802.11b clients are predominant but what is right answer for your enterprise WLAN solution?

5、 802.11b Pro: Highest market penetration Con: More interference & noise may be found in the 2.4GHz band Con: Only provides 3 non-overlapping channels Con: Can suffer from multipath issues Con: Client driver quality (consumer versus enterprise) 802.11g Pro: Higher throughput Pro: OFDM technology

6、reduces multipath issues Con: More interference & noise may be found in the 2.4GHz band Con: Only provides 3 non-overlapping channels Con: Throughput degraded in the presence of 802.11b clients 802.11a Pro: Higher throughput Pro: OFDM technology reduces multipath issues Pro: Provides FCC 24 non-

7、overlapping channels Con: Lower market penetration 802.11n Pro: MIMO/Channel combined/Packet Aggregation provide More Stable connection, higher performance and longer distance Con: Not finalized yet Con: Need more power 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID6

8、Coverage Areas Full or partial Coverage Hole Goal 0% - 10% (Typically 2% 5%) Building Construction Type Typical Offices (cubes and walled offices) Walled Offices (drywall office only) Walled Offices (brick and concrete walled offices) Other (example arenas, stock exchange, convention center, large w

9、arehouse) Building Characteristics Homogeneous same construction type throughout Cubes and walled offices throughout and/or floor to floor Heterogeneous mixed construction types Drywall office area with shipping warehouse in back部署需求部署需求覆盖覆盖 2006 Cisco Systems, Inc. All rights reserved.Cisco Confide

10、ntialPresentation_ID7部署需求部署需求妨碍物思索妨碍物思索Normal construction provides a myriad of wireless obstaclesDistant cornersWalled officeareaBreak roomwith microwaveConcrete walls with iron rebarHigh mounting positionsMeeting roomwith high peak usersElevator shaft andstair wells 2006 Cisco Systems, Inc. All ri

11、ghts reserved.Cisco ConfidentialPresentation_ID8部署需求部署需求提问提问 How many access points do I need? Purchase more AP than determined AP count At best case, will allow over-deployment to ensure seamless coverage and higher capacity allowing Cisco Airespace controller to compensate for overlap At worst cas

12、e, will cover unforeseen coverage hole Where should I place the access points? Place AP where WLAN clients will be located Do place AP in a meeting room as opposed to an adjacent hallway Do place AP in a central location which can cover several walled offices Do not place APs in a wiring closet Plac

13、e AP in the middle of coverage areas How many controllers will I need? Provide enough controllers to perform the suggested high availability schemes available to provide enterprise reliability Where should I place the controllers? Place the controllers in different wiring closet to reduce power loss

14、 issues 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID9部署需求部署需求AP摆放摆放Over cubicles outside of officesIn meeting roomwith high peak usersInside load bearing wallsPositioned to cover 2 rooms with non-load bearing walls 2006 Cisco Systems, Inc. All rights reserved.Cisco

15、ConfidentialPresentation_ID10企业无线网企业无线网覆盖和容量覆盖和容量80 ftBasic coverage, low costEnterprise coverage & capacity60 ft802.11a:11-14 Mbps802.11g:11-14 Mbps802.11b/g:2 / 2-4 Mbps802.11b:2 MbpsGraphic is using only 3 channels for interference avoidance 2006 Cisco Systems, Inc. All rights reserved.Cisco

16、ConfidentialPresentation_ID11企业无线网企业无线网战略战略 Smaller, overlapping cells Increased average capacity 802.11a can provide more channels to reduce interference Provides higher availability in the event of an AP failure APs should not be placed too close together since clients will still transmit at norma

17、l power output Clients can cause interference issues with other APS and clientsEnterprise coverage & capacity60 ft802.11a:11-14 Mbps802.11g:11-14 Mbps802.11b/g:2 / 2-4 Mbps802.11b:2 MbpsGraphic is using only 3 channels to show option to avoid interference 2006 Cisco Systems, Inc. All rights rese

18、rved.Cisco ConfidentialPresentation_ID12确定确定AP数量和位置数量和位置Z Factor Z factor allows conversion of an AP coverage area to square footage Together with the building type and average desired user performance, the Z factor calculation can quickly estimate the number of required APs 2006 Cisco Systems, Inc.

19、 All rights reserved.Cisco ConfidentialPresentation_ID13 Increased signal strength means greater throughput limited by signal standard 802.11a will have increased throughput over a wider range than 802.11bUser Throughput vs. Signal Strength0510152025-95-90-85-80-75-70-65-60-55-50Signal Strength (dBm

20、)User Throughput (Mbps)802.11b802.11aZ FactorPremiseAverage Signal 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID14Z FactorBuilding Reference 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID15Z FactorAP 数量数量 Next define the coverage area

21、for each floor in the building Divide into rectangles, then calculate APs needed by dividing the area of each rectangle by the Z factor squaredExample is for a typical office building with a desired average user throughput of 5 MbpsDue to the gain of an Cisco 1000 series AP, 10% more AP should be ad

22、ded from a given calculation 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID16Z FactorAP 位置位置 Place the AP in the center of the coverage areasExample is for omni directional antennaDue to the gain of an Cisco 1000 series AP, AP should be staggered to accommodate covera

23、ge area shape 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID17确定确定AP数量和位置数量和位置Site Survey More rigorous method to determine AP count and placement Z Factor calculation can be used to determine AP count while Site Survey can be used for actual AP placement Requires mea

24、surement of actual coverage areas to determine correct placement 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID18Site SurveyOverview Cisco 1000 series APs are configured for site survey mode First AP is placed at a zero/zero coordinate and then the Ekahau Site Survey

25、Tool is used to determine coverage boundary Then place AP on coverage boundary in the middle of the coverage area Then use Ekahau Site Survey Tool to determine new coverage boundary Then place additional AP with RF coverage areas adjacent to placed AP Then use Ekahau Site Survey Tool again to determ

26、ine additional coverage boundaries A single set of Cisco 1000 series APs can be moved to different locations on the building floor until all AP placement is defined Ekahau Site Survey tool should be used to verify the final AP placement and document the WLAN 2006 Cisco Systems, Inc. All rights reser

27、ved.Cisco ConfidentialPresentation_ID19Site SurveyCisco 1000 series AP Site Survey Mode Requires opening of Cisco 1000 series AP and setting of internal jumper Requires powering of Cisco 1000 series AP In site survey mode, the Cisco 1000 series AP is beacon only device and will not support data or m

28、onitoring services In site survey mode, the Cisco 1000 series AP Transmit power is 18 dBm for 802.11a on channel 52 Transmit power is 19 dBm for 802.11b on channel 11 In site survey mode, the Cisco 1000 series AP power LED will flash green Site survey mode will not support external antenna Site surv

29、ey mode is used exclusively for site surveys or troubleshooting 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID20Site SurveyCisco 10 xx series AP Site Survey Mode (continued)You must first open the cover by removing the screws at the base of Side A with a T-10 security

30、 TorxCisco 1000 series AP Site Survey Mode requires a physical configurationThen you must open the cover and jumper the Site Survey pins 1 & 2 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID21Site SurveyCisco 10 xx series AP Site Survey Mode (continued) Cisco 1000

31、series AP Site Survey Mode requires a power source 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID22Site SurveyAP 数量和位置数量和位置Place the AP at 0:0 coordinate of a coverage area (1).Perform a site survey to determine the signal strength of the coverage area. Mark where the

32、 rate falls to the minimum acceptable value until you have traced a semi-circular pattern on the floor which will determine the coverage boundary.Move the original AP to a centrally located position on the coverage boundary (2) to create the first coverage area. 2006 Cisco Systems, Inc. All rights r

33、eserved.Cisco ConfidentialPresentation_ID23Site SurveyAP 数量和位置数量和位置 (continued) Perform a site survey to determine the signal strength of the new coverage area. Mark where the rate falls to the minimum acceptable value until you have traced a circular pattern on the floor which will determine the coverage boundary. Note: Be sure to orientate the Ekahau site survey laptop in multiple directions to insure t