iuwne10 s01 l07
Post on 19-Jun-2015
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- 1. Wireless Fundamentals Examining Wireless Media Access
2. Sending a Frame 3. Sending a Frame (Cont.) 4. Sending a Frame (Cont.) 5. After a Frame Is Sent 6. 802.11 Frame Shape 7. Frame Types
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- Management:
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- Beacon, probe request, probe response
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- Authentication request, authentication response
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- Association request, association response
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- Deauthentication, reassociation request, reassociation response
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- Announcement Traffic Indication Message (ATIM)
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8. Frame Types (Cont.)
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- Control:
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- Request to send (RTS), clear to send (CTS), acknowledgment (ACK),
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- Power Save Poll (PS-Poll),
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- Data:
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- Simple data
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- Null function (empty frame)
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9. 802.11 Frame Speeds 10. Discovering the Network (Mgmt Frames) 11. Connecting (Mgmt Frames) 12. Staying Connected (Mgmt Frames) 13. Control Frames
- ACK is used after each frame.
RTS and CTS are used in 802.11b and g mixed cells and in hidden node situations. 14. WMM Enhancement 15. Power Save Mode 16. Summary
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- Sending a frame requires a timing and acknowledgment system that is based on CSMA/CA.
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- 802.11 frames have a specific shape with headers containing specific information and different parts that are sent at different speeds.
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- Beacons and probes help discover the network.
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- Authentication and association frames are used to join the cell.
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- Some other management frames may be used while the client is connected.
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- Control frames improve the communication framework by allowing special messages in specific cases, such as RTS and CTS or PCF.
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- Some stations may use the power save mode to increase battery time, which means there must be specific exchanges with the AP.
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