Designing Wireless Networks

Transcription

1 Designing Wireless Networks Session 2 Copyright Printed in USA.

2 Why Wireless???? How many in here have used wireless networks? How many use it at work? At home? Now How many would give it up for an Ethernet cable again? 3 A Well Designed WLAN System Properly designed WLANs can provide: Lower overall network costs Increased employee productivity Improved communication Faster adds, moves and changes All of which Means Improved Profitability! 4 Copyright Printed in USA.

3 Session Overview Defining Network Requirements Choosing the Technology Choosing the Proper WLAN Architecture Selecting the Proper Hardware Design Guidance Site Survey Issues Installation Issues 5 Defining Your Technology Requirements Questions to Ask and Answer Present applications BW requirement per user? Density of WLAN users in any given coverage area What future applications are being considered What types of client devices will be used on the WLAN? Client radio vendor single or multiple? AP Placement critical? Aesthetics critical? Any issues with regulations governing use of Building construction interference with the RF signal? 6 Copyright Printed in USA.

4 Retail Usage time Infrequent during regular hours Heavy usage during inventory Coverage for loading docks and trailers Sources of interference Inventory items 2.4 and 5 GHz equipment Co-located stores using WLANs Security 7 Warehousing Multiple users High usage Inventory Inventory types Inventory levels 8 Copyright Printed in USA.

5 Warehousing (Cont.) Keep in mind: Exposure to the elements Freezers Weatherproof enclosures Shelving Antenna mounting Forklift paths 9 Healthcare Multiple floors Numerous rooms Sensitive equipment Cautious implementation Hospital equipment should be built to a standard to avoid RF interference Security 10 Copyright Printed in USA.

6 Hotel/Hospitality Multi-floor construction Numerous rooms Throughput Fewer users per access point 11 Hot Spots Hot Spot Provider Subscribers Survey not so necessary Effective range feet Provide -agnostic network Public areas Coffee shops, restaurants, hotels Airports, convention centers, Marinas, parks Cisco Hot Spot locator link: 12 Copyright Printed in USA.

7 Education Public Areas Children/public are Curious Can be destructive Antennas and access points should be hidden to avoid damage 13 Education (Cont.) Various PC and radio client vendors Wireless users Connections to remote classrooms Workgroup Bridge a possible solution 14 Copyright Printed in USA.

8 Enterprise Office Conference Room 2.4 GHz 4 Access Points 54 Cubes 4 Conference Rooms 54 Cubes 4 Conference Rooms Conference Room Conference Room 5 GHz 16 Access Points Conference Room 120 Feet 120 Feet Conference Room Reception Conference Room Conference Room Reception Conference Room 95 Feet 95 Feet 15 Choosing the Technology 16 Copyright Printed in USA.

9 Wireless Technologies b a Direct Sequence? Ultrawide Band Frequency Hopping g 17 Migrations of the WLAN Technologies Proprietary systems Standards-based systems The demise of FH Today s products 19 Copyright Printed in USA.

10 Proprietary Systems Spread Spectrum Introduced to Commercial market in 1988 by Telesystem (Aironet) 900 MHz Maximum of 1Mb No interoperability among other vendors Bar-code scanners, specialty devices Very little general WLAN usage Became congested in mid-1990s 20 Standard (802.11) Products First Standards were completed in 1997 First products included both Frequency Hopping and Direct Sequence Data rates to 2Mb SOME interoperability: Not guaranteed and many problems Not fast enough for general WLAN deployment 21 Copyright Printed in USA.

11 Faster Products developed standards for.11a and.11b in 1999 First 11Mb 2.4GHz product introduced into market in 1999 by Aironet followed by most other WLAN vendors Wi-Fi Alliance (WECA) was formed and provided interoperability certification with.11b ONLY MS and others announce no support for FH The HomeRF Working Group disbanded January 2003 Proxim attempted to get a 10Mb FH (WBFH) into IEEE, but failed, and product never succeeded a 54Mb product start shipping in 2000 Pre-standard g product start shipping in 2003 ( g recently passed IEEE) 22 What Is Right for Your Application Bandwidth Higher bandwidth may require a or g Deployment issues: Where do the APs have to be mounted? May affect if a or 2.4GHz products are used Security issues Level of security may affect client selection Range/coverage More coverage with lower frequencies Upgradeable 23 Copyright Printed in USA.

12 Determining Bandwidth Needs Based on applications of users: Is a shared 11MB AP enough? How many users per AP? Will ALL users be on the same frequency? Can you split applications across different bands? (VoIP on 2.4, data on 5GHz) What is future BW needs for application? Will you need ability to add dual band, or to upgrade b to g? 24 Deployment Issues Aesthetics AP placement Ceiling, wall, inside ceiling mounting Antenna selection and mounting Physical security Above ceiling, out of sight Metal boxes Local regulation Plenum spaces HVAC restricted areas 25 Copyright Printed in USA.

13 Security Selection What level of security do you need? Is the Wi-Fi Protected adequate? Some APs do not support WPA today Will you require something more extensive May limit client selection to a single vendor 26 Client Selection Who will be deciding what clients are used? If it is not specified by the administrator, likely b will be the prevalent devices Will specialty devices need to be used? CE based devices, bar code scanners, print servers, etc., may not be readily available with support for a 27 Copyright Printed in USA.

14 Choosing the Proper WLAN Architecture 28 Architecture Selection Single or dual radio architecture Receiver desensitization Distributed intelligence Centralized intelligence Switched antenna array architecture MESH networks 29 Copyright Printed in USA.

15 Single Mode One channel, one operating frequency at any given time Simplest form of AP 30 Dual Radio Products 2 radios in same AP on the same RF Band Close proximity causes receiver de-sense Can create problems such as: Retries, Reduced range Lower overall throughput Both Radios Operate on 2.4GHZ 31 Copyright Printed in USA.

16 RF Energy for Dual Band AP 32 Dual Mode Products Access Point Main Processor Dual band access points are available Provides access and coverage for both 2.4 and 5Ghz clients simultaneously Can be used to increase aggregate bandwidth per cell AP needs to be designedfor higher speed radio products 33 Copyright Printed in USA.

17 Dual Mode Coverage 5GHz different coverage areas Mixing technologies will require a good up front design Provides migration path and increased throughput Design the 2.4ghz cell size to compliment future 5GHz deployment Ghz Ghz 34 Distributed Intelligence Architecture Local encryption/decryption Local authentication Faster roaming Less network traffic Higher cost of AP Lower cost of network components More secure 35 Copyright Printed in USA.

18 Centralized Intelligence Architecture Single point for authentication All traffic must hit the network Lower cost of AP Higher cost of network components More network components Less secure Single point of failure 36 Switched Antenna Array APs Phased array antenna provide higher gain, narrower beamwidths Switched Packet arrays such as Vivato utilize a large number of antenna elements (as many as 120), as well as multiple radio modules (13 in this case) Provides 3 channels (2.4Ghz) of operation with 100 degree of total beamwidth High cost ($9000 per AP) Physically large (47 x 25 ) Antenna Element 37 Copyright Printed in USA.

19 MESH Networks Relies on ad-hoc connections Routing is done below the IP layer Relies on the intelligence at the client devices Security is non-existent 38 Selecting the Hardware 39 Copyright Printed in USA.

20 What Do You Really Need? Low end or high end AP? What client devices are required? Required WLAN Service VLANs Quality of Service IP Subnet Roaming Load Balancing Security Performance Range Throughput Antenna capabilities Network Si Trunk Si Trunk VLAN 10 VLAN Why Not a Low Cost AP? Will one AP cover the entire facility? SOHO and Home APs do not concentrate on things like roaming and handoffs Do you need more than simple WPA for security? Most SOHO and home APs are not set up for many of the higher security schemes needed by industry Will you need management capabilities? While many advertise SNMP support, some only include a handful of manageable variables VoIP support? Many lower end APs utilize a low cost processor, and therefore have trouble handling the small size, yet large volume of packets required by VoIP applications VLAN, PMIP, 100mW, remote antennas, etc. OR 41 Copyright Printed in USA.

21 Various Client Devices Hundreds of clients available Wide variety of form factors available Not all are interoperable with all desired features 42 Other Issues for Comparing b/a/g Power consumption a is typically much higher in power consumption Much shorter battery life on portable devices Interface architecture 54Mb requires higher buss speeds PCMCIA not adequate PCI or card buss slots required Antenna style Limits range and performance Versatile antenna systems helps Compaq ipaq PCMCIA Slot Limited Battery Life 43 Copyright Printed in USA.

22 WLAN Design Guidance 44 Wireless Local Area Network (WLAN) Ethernet Access Point Internet Remember: An Access Point Is a SHARED Device and Has Similar Performance to a SHARED Ethernet HUB 45 Copyright Printed in USA.

23 Typical WLAN Topologies Wireless Cell Wireless Cell Channel 1 Channel 6 LAN Backbone Access Point Overlapping 10-15% Access Point Wireless Clients Wireless Clients 46 Wireless Repeater Topology Channel 1 Wireless Repeater Cell LAN Backbone Access Point Channel 1 Access Point Wireless Clients 47 Copyright Printed in USA.

24 Load Balancing Active Active Change Channel Best for high-performance requirements Requires 2 Access Points to use load balancing Provides seamless and transparent load balancing between up to three active units 48 Cables Issues Antenna need to go where USERS are! Location of antennas are not necessarily close to Switch or computer room Cable runs can be 100 or more feet to antenna location 49 Copyright Printed in USA.

25 Cable Issues A 100 foot cable can reduce distance by 30% A 30% reduction in range is approx. 50% reduction in coverage area (sq. ft.) Coverage with No Cable Coverage with 100 foot Antenna Cable 50 Interference Specialty devices can cause interference SpectraLink phone systems are common Telemetry equipment Industrial Equipment Microwave Ovens 51 Copyright Printed in USA.

26 Site Survey Issues 52 Indoor Range Comparisons 2.4 GHz/100 mw 11 Mbps 130 Ft 5.5 Mbps 180 Ft 2 Mbps 250 Ft 1 Mbps 350 Ft 5 GHz/40 mw Ft Radius Ft Ft Ft Ft Ft Ft Ft Omni 2.2 dbi 2.4 GHz and Omni 5 dbi 5 GHz AP antennas Omni 0 dbi 2.4 GHz client and Patch 5 dbi 5 GHz client Distances very greatly because of building layouts 53 Copyright Printed in USA.

27 Channel Reuse for b Indoor Site Survey Concepts Evaluate Possible Problem Areas File/Supply Room - Large Filing or Metal Cabinets Elevator Shafts Test lab Break Room- Microwave Ovens Stairwells (Reinforced Building area) 55 Copyright Printed in USA.

28 Preliminary Coverage Density Test Start with a test to see general coverage area Determine if you need small or larger cell sizes Smaller cells= lower power Larger cells = better antennas This Cell Size = Too Many Users per Cell Reduce Power to 20mW 56 Indoor Site Survey Concepts from the outside Looking in A Place Access Point at A Measure maximum range (inside building) Move AP to center of that arc (point B ) Test to ensure coverage to corner of building B 57 Copyright Printed in USA.

29 Indoor Site Survey Concepts from the outside Looking in Continue with other 4 corners Next fill in the center areas CH 1 CH 6 CH Enterprise Office Area b cell sized reduced by reducing TX power and using dipole antennas b used for normal network connection 140 users per floor 6 AP = 66Mb aggregate datarate per floor CH 1 CH 6 CH Copyright Printed in USA.

30 Increase Performance with Dual Band APs Please higher bandwidth users on 5Ghz May decide to reduce cell size a bit more Fewer users per AP More closely match 5Ghz 54Mb coverage cells 54= 324Mb 11 = 66Mb Total BW= 390Mb! Using Dual Band Client Cards Will Improve Performance Even More! 60 Healthcare Facility Survey was based on 11Mb Antennas are diversity ceiling mount omni (blends in well) except courtyard Works well except Radiology! 6dBi Patch Antenna All Antennas Are Ceiling Mount Diversity, Omni Antennas Except Courtyard Antenna Radiology Courtyard Antenna Locations Channel 1 Channel 6 Channel Copyright Printed in USA.

31 Healthcare Facility 5GHz cell All Antennas Are Ceiling Mount Diversity, Omni Antennas Except Courtyard Antenna Add Dual Band APs for Radiology b 2.4Ghz devices usable everywhere a provides higher datarates for Radiology room 6dBi Patch Antenna Radiology Courtyard Antenna Locations Channel 1 Channel 6 Channel Manufacturing Aircraft manufacturing floor (802.11b) Normal network connectivity Med BW Barcoding limited BW Printing invoices limited BW (802.11b) Video images for inspection, troubleshooting High Bandwidth (802.11a) IP Phone limited use, med bandwidth (802.11b) 6 Dual Band APs, Provide b Coverage 6 Dual Band APs, Plus 6 Other 5GHz Only APs Provide a Coverage 63 Copyright Printed in USA.

32 In-Building Design Warehouse Example, (Cont.) Maximum Coverage Autorate Negotiation Cabling Only Available at Front Yagi Antennas and Dipole Installations Issues 65 Copyright Printed in USA.

33 Antenna Splitters vs. Diversity WRONG! Freezer OK OK 2.4 GHz Technology 66 Aesthetics Antennas are unsightly Patch antenna Diversity Patch Omni Paint antenna 67 Copyright Printed in USA.

34 Plenum A compartment or chamber to which one or more air ducts are connected Forms part of the air distribution system Cat 5 cable available in plenum and non-plenum Non-plenum sheath is PVC and gives off toxic fumes when melted 68 Plenum (Cont.) Cat 5 available Plenum Non-Plenum Plenum areas Egg crate ceiling tiles No insulation Firewalls Non-plenum areas use ducting in plenum for air return 69 Copyright Printed in USA.

35 802.11a Mounting Issues Integrated antennas limit mounting locations May not be able to provide out of sight locations 5GHz Antenna 2.4GHz Antennas Typical Above Ceiling Obstacles Floor/Roof support Heat/Air Conditioning ducts Lightning Fixtures Drop Ceiling 70 NEMA Enclosures (Cont.) Mounting Plate with Standoffs Electrical Workbox Bulkhead Extender External Antenna Connector 71 Copyright Printed in USA.

36 Comparison of Technologies Coverage and Bandwidth vs. Cost Distributed Intelligence AP(Cisco AP 1100)= $800 Radius Server= $5,000 Management platform= $5,000 Centralized Intelligence AP (Symbol Mobius) = $249 Controller (24 AP per)= Management Platform= $5,000 Switched Antenna Array System AP (Vivato) = $9,000 Management Platform = $5, Centralized Intelligence 4 corporate sites 10 buildings per site, 3 floors each (6 APs per floor) Approx 180 APs per site (720 total) Max. 18 APs per switch (+ redundancy) 20 switches per site 80 total 73 Copyright Printed in USA.

37 Enterprise AP1100 Deployment 4 corporate sites 10 buildings per site, 3 floors each (6 APs per floor) Approx 180 APs per site (720 total) Heavy traffic Redundant WAN ACS servers If 1 AP fails, only small percentage of users off line 74 Switched Antenna Array AP 4 corporate sites 10 buildings per site, 3 floors each 2 AP per floor, (utilize 3 channels each) 60 APs per site (240 total) Heavy traffic Redundant WAN ACS servers Security server included in AP If 1 AP fails, 50% of users per floor are off line Total Bandwidth per floor 66Mb 75 Copyright Printed in USA.

38 Architecture Comparison for Enterprise # APS Central Intelligence 720 District Intelligence 720 Sw. Ant Array 60 Cost Per AP ,000 Total AP Cost 179, , ,000 # Switched Switch Cost 5, Total Switch Cost 400, Security Server Total Security Server Cost 0 10,000 0 Total Cost 579, , , Design Steps: Determine what you need Applications, services, clients Determine the architecture for WLAN needs Determine technology for WLAN needs Design network, based on pre-survey results Perform survey Edit design Install Document 77 Copyright Printed in USA.

39 Questions? 78 A Well Designed WLAN System Properly designed WLANs can provide: Lower overall network costs Increased employee productivity Improved communication Faster adds, moves and changes All of Which Means Improved Profitability! 79 Copyright Printed in USA.

40 For More Wireless Information Other Networkers Breakout Sessions on Wireless: ACC-1010: Introduction to Wireless Networks ACC-2011: Securing Wireless Networks ACC-2012: Managing and Diagnosing Wireless LANs ACC-2013: Design and Deployment of Outdoor Bridging Networks ACC-4010: Advanced Designs for Voice enabled Enterprise Roaming PWR-5002: Developing and Implementing an Wireless Network 80 Recommended Reading Wireless Local-Area Network Fundamentals ISBN: Available in Sept 2003 Internetworking Technologies Handbook, Third Ed. ISBN: Available on-site at the Cisco Company Store 81 Copyright Printed in USA.

41 Recommended Reading Internetworking Technologies Handbook, Fourth Ed. ISBN: Available in fall 2003 Wireless Communications ISBN: Wireless Internet Applications and Architectures ISBN: Available on-site at the Cisco Company Store 82 Please Complete Your Evaluation Form Session 83 Copyright Printed in USA.

42 84 Copyright Printed in USA.