Troubleshooting

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Troubleshooting

• Chapter 13
• Lecture 2 Notes

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DSL Internet Access

• Uses std. phone line
• Limited service area

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ADSL

• Asymmetric DSL
• Most common
• Different channels on one line
• One POTS (analog)
• One uploads 1 Mbps
• One downloads 8 Mbps

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SDSL

• Same speed up and down 1.5 Mbps
• Good for web hosting, intranets, e-commerce
• Cannot share phone line

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IDSL

• ISDN DSL
• Symmetric
• Used where SDSL and ADSL arent available
• Rate 144 Kbps

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RADSL VHDSL

• Two variations of asymmetric DSL
• Rate Adaptive DSL
• Modem modifies transmission speeds based on
  signal quality
• Uploads max 1 Mbps
• Downloads max 7 Mbps
• Very High Bit DSL
• Uses two wire pairs
• Uploads 1.6 Mbps
• Downloads 13 Mbps

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DSL Quality Factors

• Location (distance from provider)
• Security
• Always on

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Troubleshooting DSL

• Physical cables
• NIC (LED)
• Drivers (NIC)
• Protocol configuration
• DSL LED
• Call DSL provider

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Cable Access

• Always on
• Shares TV digital cable line
• Requires cable modem
• Coax connection ? provider
• UTP connection ? PC/hub/switch

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Cable Troubleshooting

• Physical cables, hub
• Switches, routers
• Protocol configuration
• Modem LED
• Unplug/plug power to modem
• Call cable provider

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One-way Home Satellite

• Requires satellite card and dish
• Outgoing - phone line
• Incoming satellite link
• Asymmetric

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Two-way Home Satellite

• Requires satellite card and dish
• Outgoing satellite link
• Incoming satellite link
• Asymmetric

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Satellite Factors

• Atmospheric conditions significantly affect
  performance.
• Propagation time .5 5 seconds
• Line of site
• Configuration is very precise
• Troubleshooting
• Call tech support

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Wireless Internet Access

• Requirements
• WAP
• Service provider

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Wireless Factors

• Environmental conditions
• Fog
• Electrical interference

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Troubleshooting - Wireless

• Check configuration of wireless interface
• Drivers
• Protocols
• Check the access area for dead spots
• Check w/other users
• Contact wireless provider

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POTS Access

• Most popular method
• Requirements
• Modem
• ISP

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Troubleshooting POTS

• Physical cables
• Check for dial tone
• Check the phone number to the ISP
• Call the ISP
• Check for busy signal
• Check username and password
• Check connection settings
• IP address (DHCP)
• Has user exceeded allotted minutes?
• Try connecting at lower speed
• Disable call-waiting
• Test with AT commands

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AT Commands

• ATA sets modem to auto-answer
• ATH hangs up
• ATD dials number
• ATZ resets modem
• ATI3 displays modem name and model

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