Wireless TechnologyWireless Technology

Charles R. WolfeCharles R. Wolfe

Network ArchitectNetwork Architect

Georgetown UniversityGeorgetown University

What is Wireless?What is Wireless?(Socially)(Socially)

““The untethering of users from wired The untethering of users from wired connections while providing for the connections while providing for the ability to stay connected to a digital ability to stay connected to a digital world through the use of radio world through the use of radio frequencies”frequencies”

CISCO AIRONET 350 SERIES

WIRELESS ACCESS POINT

SD

ACTPAR

1

ACTPAR

2

ACTPAR

3

ACTPAR

4

ACTPAR

5

ACTPAR

6

ACTPAR

7

ACTPAR

8

ACTPAR

9

ACTPAR

10

ACTPAR

11

ACTPAR

12

ACTPAR

13

ACTPAR

14

ACTPAR

15

ACTPAR

16

ACTPAR

17

ACTPAR

18

ACTPAR

19

ACTPAR

20

TX RX ATTACH

PWR MODE FAULTSTACK

CISCO YSTEMSS

RESET

EIA232

Catalyst 3900

What is Wireless?What is Wireless?(Technically)(Technically)

• Shared Ethernet CharacteristicsShared Ethernet Characteristics• Uses Radio FrequenciesUses Radio Frequencies

2.4Ghz2.4Ghz 5Ghz5Ghz

• Currently 3 VersionsCurrently 3 Versions 802.11b (2.4Ghz)802.11b (2.4Ghz) 802.11g (2.4Ghz)802.11g (2.4Ghz) 802.11a (5Ghz)802.11a (5Ghz)

802.11b802.11b

2.4Ghz2.4Ghz 11Mbps11Mbps

• 6Mbps approximate throughput6Mbps approximate throughput• Range ~160ftRange ~160ft

Distance reduces bandwidthDistance reduces bandwidth 3 Frequency Channels available for 3 Frequency Channels available for

engineeringengineering

802.11g802.11g

2.4Ghz2.4Ghz Backwards compatible with 802.11bBackwards compatible with 802.11b 54Mbps54Mbps

• 22Mbps approximate throughput22Mbps approximate throughput• 8Mbps with 802.11b clients attached8Mbps with 802.11b clients attached• Range ~90ftRange ~90ft

Distance reduces bandwidthDistance reduces bandwidth 3 Frequency Channels available for 3 Frequency Channels available for

engineeringengineering

802.11a802.11a

5Ghz5Ghz 54Mbps54Mbps

• 25Mbps approximate throughput25Mbps approximate throughput• Range ~50ftRange ~50ft

Distance reduces bandwidthDistance reduces bandwidth 12 Frequency Channels available for 12 Frequency Channels available for

engineeringengineering Not compatible with 802.11b/gNot compatible with 802.11b/g

Georgetown University Georgetown University Wireless LAN ProjectWireless LAN Project

Evaluate the state of 802.11 and other wireless LAN Evaluate the state of 802.11 and other wireless LAN technologies and the feasibility of their use at technologies and the feasibility of their use at GeorgetownGeorgetown

Evaluate 802.11 wireless LAN products from leading Evaluate 802.11 wireless LAN products from leading vendors and select one as the standard for a vendors and select one as the standard for a Georgetown university enterprise wireless LANGeorgetown university enterprise wireless LAN

Develop strategies to integrate 802.11 wireless LANs Develop strategies to integrate 802.11 wireless LANs into the Georgetown network infrastructureinto the Georgetown network infrastructure

Assist in the establishment of a wireless LAN policy for Assist in the establishment of a wireless LAN policy for Georgetown UniversityGeorgetown University

Why Use WirelessWhy Use Wireless

Enhance working conditions and Enhance working conditions and productivity for staffproductivity for staff

Access to e-mail when out of the Access to e-mail when out of the officeoffice

Use of network applications while Use of network applications while mobilemobile

Provide network access to visitorsProvide network access to visitors

Reasons for Wireless at GeorgetownReasons for Wireless at Georgetown

Enhance the teaching and learning Enhance the teaching and learning environment at Georgetownenvironment at Georgetown• Classroom wireless applicationsClassroom wireless applications• Mobile wireless labsMobile wireless labs• Network connectivity to the librariesNetwork connectivity to the libraries

Provide network access to areas difficult Provide network access to areas difficult or costly to wireor costly to wire• Not a substitute for wired network.Not a substitute for wired network.

Provide a uniform rolloutProvide a uniform rollout

WhereWhere to use Wireless to use Wireless

Conference RoomsConference Rooms Guest Access AreasGuest Access Areas Hotel LobbiesHotel Lobbies Businesses (Starbucks)Businesses (Starbucks)

Where is Georgetown using Where is Georgetown using WirelessWireless

Conference RoomsConference Rooms Guest Access AreasGuest Access Areas LibrariesLibraries ClassroomsClassrooms Lecture HallsLecture Halls CafeteriasCafeterias Adjunct to wired infrastructureAdjunct to wired infrastructure

Overlapping WirelessOverlapping WirelessCells Provide Cells Provide

Seamless Roaming.Seamless Roaming.

CurrentCurrent Use Statistics Use Statistics

DailyDaily

YearYear

How is it being UsedHow is it being Used

Staying in contact with Friends and FamilyStaying in contact with Friends and Family• E-mailE-mail• Instant MessagingInstant Messaging

Collaborative studying among groupsCollaborative studying among groups On the spot access to research material on On the spot access to research material on

the webthe web Web SurfingWeb Surfing Learning and Teaching tool enhancerLearning and Teaching tool enhancer

• PACE SystemPACE System

Patient and Clinical Encounter Patient and Clinical Encounter (PACE)(PACE)

• Medical Students log patient encounters Medical Students log patient encounters in real time during clinical clerkship in real time during clinical clerkship

• Information is entered on the PDA/WebInformation is entered on the PDA/Web• Replaces traditional paper methods of Replaces traditional paper methods of

collecting datacollecting data• Provides timely faculty/student feedbackProvides timely faculty/student feedback• Insures consistencyInsures consistency• Aggregated report data can later be Aggregated report data can later be

viewed and analyzedviewed and analyzed

Impact on Traditional ITImpact on Traditional IT

Tracking of misbehaving users difficultTracking of misbehaving users difficult BandwidthBandwidth Network ManagementNetwork Management Wireless LAN deployment is more of an art Wireless LAN deployment is more of an art

than a sciencethan a science• Site surveysSite surveys

InterferenceInterference• MicrowavesMicrowaves• Cordless PhonesCordless Phones

Wireless IssuesWireless Issues SecuritySecurity

• Wired Equivalent Privacy (WEP)Wired Equivalent Privacy (WEP)• Wi-Fi Protected Access (WPA)Wi-Fi Protected Access (WPA)• (802.11i)(802.11i)

Quality of Service (QoS)Quality of Service (QoS)• IssuesIssues• Distributed Coordination Function (DCF)Distributed Coordination Function (DCF)• (802.11e)(802.11e)

Bandwidth Bandwidth • (802.11n)(802.11n)

Original 802.11 Security FeaturesOriginal 802.11 Security Features

The Service Set Identifier (SSID)The Service Set Identifier (SSID)

Media Access Control (MAC) address filteringMedia Access Control (MAC) address filtering

Wired Equivalent Privacy (WEP) encryptionWired Equivalent Privacy (WEP) encryption• Easy to CrackEasy to Crack

Encryption Key easy to recoverEncryption Key easy to recover• Could be strengthenedCould be strengthened

Virtual Private Networks (VPN)Virtual Private Networks (VPN) 802.1x authentication802.1x authentication

Industry demanded better optionIndustry demanded better option

Wi-Fi Protected Access Wi-Fi Protected Access (WPA)(WPA)

Improved Data EncryptionImproved Data Encryption• Temporal Key Integrity Protocol (TKIP)Temporal Key Integrity Protocol (TKIP)

Per-packet mixing functionPer-packet mixing function Message Integrity Check (MIC/Michael)Message Integrity Check (MIC/Michael) Extended Initialization Vector (IVR)Extended Initialization Vector (IVR)

User AuthenticationUser Authentication• 802.1x802.1x• Extensible Authentication Protocol (EAP)Extensible Authentication Protocol (EAP)

Multiple Options (TLS, TTLS, PEAP …)Multiple Options (TLS, TTLS, PEAP …) Greenfield implementations easierGreenfield implementations easier

802.11i 802.11i

Wi-Fi Protected Access 2 (WPA2)Wi-Fi Protected Access 2 (WPA2) Advanced Encryption Standard Advanced Encryption Standard

(AES)(AES) Backwards compatible with WPABackwards compatible with WPA Federal Information Processing Federal Information Processing

Standards (FIPS) compliantStandards (FIPS) compliant

QoS IssuesQoS Issues

Latency/DelayLatency/Delay• Time to deliver a packetTime to deliver a packet

Variable – CongestionVariable – Congestion Fixed – Packet encoding/decodingFixed – Packet encoding/decoding

JitterJitter• End-to-End latency differenceEnd-to-End latency difference

LossLoss• Packet dropsPacket drops

Original 802.11 QoSOriginal 802.11 QoS Carrier Sense Multiple Access with Collision Carrier Sense Multiple Access with Collision

Avoidance (CSMA/CA)Avoidance (CSMA/CA)• ““Listen before talking”Listen before talking”

Distributed Coordination Function (DCF)Distributed Coordination Function (DCF)• Clear Channel AssessmentClear Channel Assessment• Interframe SpaceInterframe Space• Contention Window (Random backoff)Contention Window (Random backoff)

Point Coordination Function (PCF)Point Coordination Function (PCF)• AccessPoint (AP) is “traffic cop”AccessPoint (AP) is “traffic cop”• Stations Transmit only when polledStations Transmit only when polled• No ContentionNo Contention• Not widely implementedNot widely implemented

802.11e802.11e

Hybrid Coordination Function (HCF)Hybrid Coordination Function (HCF)• 2 modes2 modes

Enhanced Distributed Channel Access Enhanced Distributed Channel Access (EDCA)(EDCA)

HCF Controlled Channel Access (HCCA)HCF Controlled Channel Access (HCCA)

Eight priority levelsEight priority levels Varying backoff timesVarying backoff times

802.11e Uses802.11e Uses

VideoVideo Multimedia StreamingMultimedia Streaming Voice over WirelessVoice over Wireless

802.11n802.11n

Increased bandwidth ~100MbpsIncreased bandwidth ~100Mbps 2 competing groups2 competing groups

• Task Group N (TGn)Task Group N (TGn) 5Ghz Spectrum/40Mhz Channels5Ghz Spectrum/40Mhz Channels

• World Wide Spectrum Efficiency (WWiSE)World Wide Spectrum Efficiency (WWiSE) 2.4GHz Spectrum/20MHz Channels2.4GHz Spectrum/20MHz Channels

Multiple Input Multiple Output (MIMO)Multiple Input Multiple Output (MIMO)• Additional antenna’sAdditional antenna’s• Greater increase in bandwidthGreater increase in bandwidth