Network+ 6th edition chapter 08
-
Upload
jayant-ityalam -
Category
Education
-
view
179 -
download
1
description
Transcript of Network+ 6th edition chapter 08
![Page 1: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/1.jpg)
Network+ Guide to Networks6th Edition
Chapter 8Wireless Networking
![Page 2: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/2.jpg)
Objectives
• Explain how nodes exchange wireless signals• Identify potential obstacles to successful wireless
transmission and their repercussions, such as interference and reflection
• Understand WLAN (wireless LAN) architecture
Network+ Guide to Networks, 6th Edition 2
![Page 3: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/3.jpg)
Objectives (cont’d.)
• Specify the characteristics of popular WLAN transmission methods, including 802.11 a/b/g/n
• Install and configure wireless access points and their clients
• Describe wireless WAN technologies, including 802.16 (WiMAX), HSPA+, LTE, and satellite communications
Network+ Guide to Networks, 6th Edition 3
![Page 4: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/4.jpg)
The Wireless Spectrum
• Continuum of electromagnetic waves– Data, voice communication– Arranged by frequencies
• Lowest to highest– Spans 9 KHz and 300 GHz
• Wireless services associated with one area• FCC oversees United States frequencies• ITU oversees international frequencies
– Air signals propagate across borders
Network+ Guide to Networks, 6th Edition 4
![Page 5: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/5.jpg)
5Network+ Guide to Networks, 6th Edition
Figure 8-1 The wireless spectrum
Courtesy Course Technology/Cengage Learning
![Page 6: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/6.jpg)
Characteristics of Wireless Transmission
• Similarities with wired– Layer 3 and higher protocols– Signal origination
• From electrical current, travel along conductor
• Differences from wired– Signal transmission
• No fixed path, guidance
• Antenna– Signal transmission and reception– Same frequency required on each antenna
Network+ Guide to Networks, 6th Edition 6
![Page 7: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/7.jpg)
7Network+ Guide to Networks, 6th Edition
Figure 8-2 Wireless transmission and reception
Courtesy Course Technology/Cengage Learning
![Page 8: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/8.jpg)
Antennas
• Radiation pattern – Relative strength over three-dimensional area
• Of all electromagnetic energy that antenna sends, receives
• Directional antenna– Issues wireless signals along single direction
• Omnidirectional antenna– Issues, receives wireless signals
• Equal strength, clarity in all directions
• Range– Reachable geographical area
Network+ Guide to Networks, 6th Edition 8
![Page 9: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/9.jpg)
Signal Propagation
• LOS (line-of-sight)– Signal travels in straight line
• Directly from transmitter to receiver
• Obstacles affect signal travel; signals may:– Pass through them– Be absorbed into them– Be subject to three phenomena
• Reflection: bounce back to source• Diffraction: splits into secondary waves• Scattering: diffusion in multiple different directions
Network+ Guide to Networks, 6th Edition 9
![Page 10: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/10.jpg)
Signal Propagation (cont’d.)
• Multipath signals– Wireless signals follow different paths to destination– Caused by reflection, diffraction, scattering– Advantage
• Better chance of reaching destination– Disadvantage
• Signal delay
Network+ Guide to Networks, 6th Edition 10
![Page 11: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/11.jpg)
11Network+ Guide to Networks, 6th Edition
Figure 8-3 Multipath signal propagation
Courtesy Course Technology/Cengage Learning
![Page 12: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/12.jpg)
Signal Degradation
• Fading– Variation in signal strength
• Electromagnetic energy scattered, reflected, diffracted• Attenuation
– Signal weakens• Moving away from transmission antenna
– Correcting signal attenuation• Amplify (analog), repeat (digital)
• Noise– Significant problem
• No wireless conduit, shielding
Network+ Guide to Networks, 6th Edition 12
![Page 13: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/13.jpg)
Frequency Ranges
• 2.4-GHz band (older)– Frequency range: 2.4–2.4835 GHz– 11 unlicensed communications channels– Susceptible to interference
• Unlicensed: no FCC registration required• 5-GHz band (newer)
– Frequency bands• 5.1 GHz, 5.3 GHz, 5.4 GHz, 5.8 GHz
– 24 unlicensed bands, each 20 MHz wide– Used by weather, military radar communications
Network+ Guide to Networks, 6th Edition 13
![Page 14: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/14.jpg)
Narrowband, Broadband, and Spread-Spectrum Signals
• Narrowband– Transmitter concentrates signal energy at single
frequency, very small frequency range• Broadband
– Relatively wide wireless spectrum band– Higher throughputs than narrowband
• Spread-spectrum– Multiple frequencies used to transmit signal– Offers security
Network+ Guide to Networks, 6th Edition 14
![Page 15: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/15.jpg)
Narrowband, Broadband, and Spread-Spectrum Signals (cont’d.)
• FHSS (frequency hopping spread spectrum)– Signal jumps between several different frequencies
within band– Synchronization pattern known only to channel’s
receiver, transmitter• DSSS (direct-sequence spread spectrum)
– Signal’s bits distributed over entire frequency band at once
– Each bit coded• Receiver reassembles original signal upon receiving
bits
Network+ Guide to Networks, 6th Edition 15
![Page 16: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/16.jpg)
16Network+ Guide to Networks, 6th Edition
Figure 8-4 FHSS (frequency hopping spread spectrum)Courtesy Course Technology/Cengage Learning
![Page 17: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/17.jpg)
17Network+ Guide to Networks, 6th Edition
Figure 8-5 DSSS (direct sequence spread spectrum)
Courtesy Course Technology/Cengage Learning
![Page 18: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/18.jpg)
Fixed versus Mobile
• Fixed communications wireless systems– Transmitter, receiver locations do not move– Transmitting antenna focuses energy directly toward
receiving antenna• Point-to-point link results
– Advantage• No wasted energy issuing signals• More energy used for signal itself
• Mobile communications wireless systems– Receiver located anywhere within transmitter’s range
Network+ Guide to Networks, 6th Edition 18
![Page 19: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/19.jpg)
WLAN (Wireless LAN) Architecture
• Ad hoc WLAN– Wireless nodes transmit directly to each other– Use wireless NICs
• No intervening connectivity device– Poor performance
• Many spread out users, obstacles block signals
• Wireless access point (WAP)– Accepts wireless signals from multiple nodes
• Retransmits signals to network– Base stations, wireless routers, wireless gateways
Network+ Guide to Networks, 6th Edition 19
![Page 20: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/20.jpg)
WLAN Architecture (cont’d.)
• Infrastructure WLAN– Stations communicate with access point
• Not directly with each other– Access point requires sufficient power, strategic
placement• WLAN may include several access points
– Dependent upon number of stations– Maximum number varies: 10-100
Network+ Guide to Networks, 6th Edition 20
![Page 21: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/21.jpg)
21Network+ Guide to Networks, 6th Edition
Figure 8-7 An infrastructure WLAN
Courtesy Course Technology/Cengage Learning
![Page 22: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/22.jpg)
WLAN Architecture (cont’d.)
• Mobile networking allows roaming wireless nodes– Range dependent upon wireless access method,
equipment manufacturer, office environment• Access point range: 300 feet maximum
• Can connect two separate LANs– Fixed link, directional antennas between two access
points• Allows access points 1000 feet apart
• Support for same protocols, operating systems as wired LANs– Ensures compatibility
Network+ Guide to Networks, 6th Edition 22
![Page 23: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/23.jpg)
23Network+ Guide to Networks, 6th Edition
Figure 8-8 Wireless LAN interconnection
Courtesy Course Technology/Cengage Learning
![Page 24: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/24.jpg)
802.11 WLANs
• Wireless technology standards– Describe unique functions
• Physical and Data Link layers– Differences between standards
• Specified signaling methods, geographic ranges, frequency usages
– Most popular: developed by IEEE’s 802.11 committee• Notable Wi-Fi standards
– 802.11b, 802.11a, 802.11g, 802.11n– Share characteristics
• Half-duplexing, access methodNetwork+ Guide to Networks, 6th Edition 24
![Page 25: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/25.jpg)
Access Method
• 802.11 MAC services– Append 48-bit (6-byte) physical addresses to frame
• Identifies source, destination
• Same physical addressing scheme as 802.3– Allows easy combination
• Wireless devices– Not designed to simultaneously transmit and receive– Cannot quickly detect collisions– Use different access method
Network+ Guide to Networks, 6th Edition 25
![Page 26: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/26.jpg)
Access Method (cont’d.)
• CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)– Minimizes collision potential– Uses ACK packets to verify every transmission
• Requires more overhead than 802.3• Real throughput less than theoretical maximum
• RTS/CTS (Request to Send/Clear to Send) protocol– Optional– Ensures packets not inhibited by other transmissions– Efficient for large transmission packets– Further decreases overall 802.11 efficiency
Network+ Guide to Networks, 6th Edition 26
![Page 27: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/27.jpg)
27Network+ Guide to Networks, 6th Edition
Figure 8-9 CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance
Courtesy Course Technology/Cengage Learning
![Page 28: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/28.jpg)
Association
• Packet exchanged between computer and access point– Gain Internet access
• Scanning– Surveys surroundings for access point– Active scanning transmits special frame
• Probe– Passive scanning listens for special signal
• Beacon fame
Network+ Guide to Networks, 6th Edition 28
![Page 29: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/29.jpg)
Association (cont’d.)
• SSID (service set identifier)– Unique character string identifying access point
• In beacon frame information– Configured in access point– Better security, easier network management
• BSS (basic service set)– Station groups sharing access point – BSSID (basic service set identifier)
• Station group identifier
Network+ Guide to Networks, 6th Edition 29
![Page 30: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/30.jpg)
Association (cont’d.)
• ESS (extended service set)– Access point group connecting same LAN
• Share ESSID (extended service set identifier)– Allows roaming
• Station moving from one BSS to another without losing connectivity
• Several access points detected– Select strongest signal, lowest error rate– Poses security risk
• Powerful, rogue access point
Network+ Guide to Networks, 6th Edition 30
![Page 31: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/31.jpg)
31Network+ Guide to Networks, 6th Edition
Figure 8-10 A network with a single BSS
Courtesy Course Technology/Cengage Learning
![Page 32: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/32.jpg)
32Network+ Guide to Networks, 6th Edition
Figure 8-11 A network with multiple BSSs forming an ESS
Courtesy Course Technology/Cengage Learning
![Page 33: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/33.jpg)
Association (cont’d.)
• ESS with several authorized access points– Must allow station association with any access point
• While maintaining network connectivity
• Reassociation– Mobile user moves from one access point’s range into
another’s range– Occurs by simply moving; high error rate
• Stations’ scanning feature– Used to automatically balance transmission loads
• Between access points
Network+ Guide to Networks, 6th Edition 33
![Page 34: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/34.jpg)
Frames
• 802.11 networks overhead– ACKs, probes, and beacons
• 802.11 specifies MAC sublayer frame type• Multiple frame type groups
– Control: medium access and data delivery• ACK and RTS/CTS frames
– Management: association and reassociation– Data: carry data sent between stations
Network+ Guide to Networks, 6th Edition 34
![Page 35: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/35.jpg)
35Network+ Guide to Networks, 6th Edition
Figure 8-12 Basic 802.11 data frame compared with an 802.3 (Ethernet) frameCourtesy Course Technology/Cengage Learning
![Page 36: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/36.jpg)
Frames (cont’d.)
• 802.11 data frame overhead– Four address fields
• Source address, transmitter address, receiver address, and destination address
– Sequence Control field• How large packet fragmented
– Frame Control field• Wi-Fi share MAC sublayer characteristics• Wi-Fi differ in modulation methods, frequency
usage, and range
Network+ Guide to Networks, 6th Edition 36
![Page 37: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/37.jpg)
802.11b
• 2.4-GHz band– Separated into 22-MHz channels
• Throughput– 11-Mbps theoretical– 5-Mbps actual
• 100 meters node limit• Oldest, least expensive• Being replaced by 802.11g
Network+ Guide to Networks, 6th Edition 37
![Page 38: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/38.jpg)
802.11a
• Released after 802.11b• 5-GHz band
– Not congested like 2.4-GHz band• Lower interference, requires more transmit power
• Throughput– 54 Mbps theoretical– 11 and 18 Mbps effective
• 20 meter node limit• Requires additional access points• Rarely preferred
Network+ Guide to Networks, 6th Edition 38
![Page 39: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/39.jpg)
802.11g
• Affordable as 802.11b• Throughput
– 54 Mbps theoretical– 20 to 25 Mbps effective
• 100 meter node range• 2.4-GHz frequency band
– Compatible with 802.11b networks
Network+ Guide to Networks, 6th Edition 39
![Page 40: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/40.jpg)
802.11n
• Standard ratified in 2009• Primary goal
– Wireless standard providing much higher effective throughput
• Maximum throughput: 600 Mbps– Threat to Fast Ethernet
• Backward compatible with 802.11a, b, g standards
Network+ Guide to Networks, 6th Edition 40
![Page 41: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/41.jpg)
802.11n (cont’d.)
• 2.4-GHz or 5-GHz frequency range• Compared with 802.11a, 802.11g
– Same data modulation techniques• Compared with three 802.11 standards
– Manages frames, channels, and encoding differently• Allows high throughput
Network+ Guide to Networks, 6th Edition 41
![Page 42: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/42.jpg)
802.11n (cont’d.)
• MIMO (multiple input-multiple output)– Multiple access point antennas may issue signal to
one or more receivers– Increases network’s throughput, access point’s range
Network+ Guide to Networks, 6th Edition 42
Figure 8-13 802.11n access point with three antennas
Courtesy Cisco Systems, Inc.
![Page 43: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/43.jpg)
802.11n (cont’d.)
• Channel bonding– Two adjacent 20-MHz channels bonded to make 40-
MHz channel• Doubles the bandwidth available in single 20-MHz
channel• Bandwidth reserved as buffers assigned to carry data
• Higher modulation rates– Single channel subdivided into multiple, smaller
channels• More efficient use of smaller channels• Different encoding methods
Network+ Guide to Networks, 6th Edition 43
![Page 44: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/44.jpg)
802.11n (cont’d.)
• Frame aggregation– Combine multiple frames into one larger frame– Advantage: reduces overhead
Network+ Guide to Networks, 6th Edition 44
Figure 8-15 Aggregated 802.11n frame
Courtesy Course Technology/Cengage Learning
![Page 45: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/45.jpg)
802.11n (cont’d.)
• Maximum throughput dependencies– Number and type of strategies used– 2.4-GHz or 5-GHz band– Actual throughput: 65 to 600 Mbps
• Backward compatible– Not all 802.11n features work
• Recommendation– Use 802.11n-compatible devices
Network+ Guide to Networks, 6th Edition 45
![Page 46: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/46.jpg)
46Network+ Guide to Networks, 6th Edition
Table 8-1 Wireless standards
Courtesy Course Technology/Cengage Learning
![Page 47: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/47.jpg)
Implementing a WLAN
• Designing a small WLAN– Home, small office
• Formation of larger, enterprise-wide WANs• Installing and configuring access points and clients• Implementation pitfalls
Network+ Guide to Networks, 6th Edition 47
![Page 48: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/48.jpg)
Determining the Design
• One access point– Combine with switching, routing functions– Connects wireless clients to LAN– Acts as Internet gateway
• Access point WLAN placement considerations– Typical distances between access point and client– Obstacles
• Type and number of, between access point and clients
Network+ Guide to Networks, 6th Edition 48
![Page 49: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/49.jpg)
49Network+ Guide to Networks, 6th Edition
Figure 8-16 Home or small office WLAN arrangementCourtesy Course Technology/Cengage Learning
![Page 50: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/50.jpg)
Determining the Design (cont’d.)
• Larger WLANs– Systematic approach to access point placement
• Site survey– Assesses client requirements, facility characteristics,
coverage areas– Determines access point arrangement ensuring
reliable wireless connectivity• Within given area
– Proposes access point testing• Test wireless access from farthest corners
Network+ Guide to Networks, 6th Edition 50
![Page 51: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/51.jpg)
Determining the Design (cont’d.)
• Install access points– Must belong to same ESS, share ESSID
• Enterprise-wide WLAN design considerations– How wireless LAN portions will integrate with wired
portions
Network+ Guide to Networks, 6th Edition 51
![Page 52: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/52.jpg)
52Network+ Guide to Networks, 6th Edition
Figure 8-17 Enterprise-wide WLAN
Courtesy Course Technology/Cengage Learning
![Page 53: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/53.jpg)
Configuring Wireless Connectivity Devices
• Access point CD-ROM or DVD– Guides through setup process
• Variables set during installation– Administrator password– SSID– Whether or not DHCP is used– Whether or not the SSID is broadcast– Security options
Network+ Guide to Networks, 6th Edition 53
![Page 54: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/54.jpg)
Configuring Wireless Clients
• Configuration varies from one client type to another• Linux and UNIX clients wireless interface
configuration– Use graphical interface– iwconfig command-line function
• View, set wireless interface parameters
Network+ Guide to Networks, 6th Edition 54
![Page 55: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/55.jpg)
55Network+ Guide to Networks, 6th Edition
Figure 8-18 Output from iwconfig commandCourtesy Course Technology/Cengage Learning
![Page 56: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/56.jpg)
Avoiding Pitfalls
• Access point versus client configurations– SSID mismatch– Incorrect encryption– Incorrect channel, frequency– Standard mismatch (802.11 a/b/g/n)
• Incorrect antenna placement– Verify client within 330 feet
• Interference– Check for EMI sources
Network+ Guide to Networks, 6th Edition 56
![Page 57: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/57.jpg)
Wireless WANs
• Wireless broadband– Latest wireless WAN technologies– Specifically designed for:
• High-throughput; long-distance digital data exchange
Network+ Guide to Networks, 6th Edition 57
![Page 58: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/58.jpg)
802.16 (WiMAX)
• WiMAX (Worldwide Interoperability for Microwave Access)– Most popular version: 802.16e (2005)– Improved WiMAX version: 802.16m (2011)– Functions in 2-11 or 11-66 GHz range– Licensed or nonlicensed frequencies
• Ability to transmit and receive signals up to 30 miles– With fixed antennas– About 10 miles when antennas are mobile
Network+ Guide to Networks, 6th Edition 58
![Page 59: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/59.jpg)
802.16 (WiMAX) (cont’d.)
• 802.16m – Positioned to compete favorably with cellular data
services– Backwards compatible with 802.16e equipment
• Maximum throughput – Downlink: 120Mbps– Uplink: 60Mbps– Future improvements could take to 1Gbps
Network+ Guide to Networks, 6th Edition 59
![Page 60: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/60.jpg)
60Network+ Guide to Networks, 6th Edition
Figure 8-19 WiMAX network
Courtesy Course Technology/Cengage Learning
![Page 61: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/61.jpg)
61Network+ Guide to Networks, 6th Edition
Figure 8-20 WiMAX residential antenna
Courtesy of Laird Technologies
![Page 62: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/62.jpg)
Cellular
• Initially designed for analog telephone service– Today deliver data and voice
• Cellular technology generations– 1G: analog– 2G: digital transmission up to 240Kbps– 3G: data rates up to 384Kbps
• Data communications use packet switching– 4G: all-IP, packet switched network for data and voice
Network+ Guide to Networks, 6th Edition 62
![Page 63: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/63.jpg)
Cellular (cont’d.)
• Network infrastructure– Cells served by antenna and base station– Controller assigns mobile clients frequencies
• Cell size depends on:– Network’s access method– Region topology– Population– Amount of cellular traffic
Network+ Guide to Networks, 6th Edition 63
![Page 64: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/64.jpg)
64Network+ Guide to Networks, 6th Edition
Figure 8-22 Cellular network
Courtesy Course Technology/Cengage Learning
![Page 65: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/65.jpg)
Cellular (cont’d.)
• Basic infrastructure– HSPA+ (High Speed Packet Access Plus)
• 3G technology– LTE (Long Term Evolution)
• 4G technology
Network+ Guide to Networks, 6th Edition 65
Table 8-2 Characteristics of some wireless WAN servicesCourtesy Course Technology/Cengage Learning
![Page 66: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/66.jpg)
Satellite
• Used to deliver:– Digital television and radio signals– Voice and video signals– Cellular and paging signals– Data services to mobile clients in remote locations
• Most popular satellite orbit– Geosynchronous Earth orbit (GEO)
• Satellites orbit at same rate Earth turns
Network+ Guide to Networks, 6th Edition 66
![Page 67: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/67.jpg)
Satellite (cont’d.)
• Downlink– Satellite transponder transmits signal to Earth-based
receiver• Typical satellite
– 24 to 32 transponders– Unique downlink frequencies
Network+ Guide to Networks, 6th Edition 67
![Page 68: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/68.jpg)
Satellite (cont’d.)
• Satellite frequency bands– L-band—1.5–2.7 GHz– S-band—2.7–3.5 GHz– C-band—3.4–6.7 GHz– Ku-band—12–18 GHz– Ka-band—18–40 GHz
• Within bands– Uplink, downlink transmissions differ
Network+ Guide to Networks, 6th Edition 68
![Page 69: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/69.jpg)
Satellite (cont’d.)
• Satellite Internet services– Subscriber uses small satellite dish antenna, receiver– Exchanges signals with provider’s satellite network– Typically asymmetrical– Bandwidth shared among many subscribers– Throughput controlled by service provider– Slower, more latency than other wireless WAN
options
Network+ Guide to Networks, 6th Edition 69
![Page 70: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/70.jpg)
70Network+ Guide to Networks, 6th Edition
Figure 8-23 Satellite communication
Courtesy Course Technology/Cengage Learning
![Page 71: Network+ 6th edition chapter 08](https://reader033.fdocuments.net/reader033/viewer/2022061214/549a088ab47959002c8b4728/html5/thumbnails/71.jpg)
Summary
• Wireless spectrum used for data and voice communications– Each type of service associated with specific
frequency band• Wireless communication: fixed or mobile• Standards vary by frequency, signal method, and
range– Notable wireless standards include 802.11 a/b/g/n
• WiMAX 2: specified in IEEE’s 802.16m standard• Satellites can provide wireless data services
Network+ Guide to Networks, 6th Edition 71