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ECE 424 Embedded Systems Design

ECE 424 Embedded Systems Design. Networking Connectivity Chapter 12 Ning Weng. Networking Overview. Goal: key concepts and system details to integrate network connectivity into embedded systems. Global Internet Bandwidth. UDP Packet Sender. UDP Packet Sender in C. Socket API.

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ECE 424 Embedded Systems Design

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  1. ECE 424 Embedded Systems Design Networking Connectivity Chapter 12 NingWeng

  2. Networking Overview • Goal: key concepts and system details to integrate network connectivity into embedded systems ECE 424

  3. Global Internet Bandwidth ECE 424

  4. UDP Packet Sender ECE 424

  5. UDP Packet Sender in C ECE 424

  6. Socket API ECE 424

  7. Protocol Layers ECE 424

  8. IP Layer Packet Headers ECE 424

  9. Comparison: IPv4&6 header

  10. Transport Layer Headers ECE 424

  11. TCP connections • This diagram shows the start of a TCP connection. A sends packet X with SYN. “Hello I would like to talk”. B sends a SYN, ACK pair “I got your message. I would also like to talk” A sends an ACK (and some data) “I got your message, here is some data.”

  12. TCP Window Increase/Decrease Congestion window The initial doubling of the window size is called “slow start”. Timeout Threshold Threshold Transmission no

  13. Encapsulation ECE 424

  14. Example of Switched Ethernet LAN ECE 424

  15. Ethernet Frame Format ECE 424

  16. Ethernet Controller ECE 424

  17. WI-FI • Short of wireless fidelity • Dominant wireless LAN technologies • Relying on availability of unlicensed radio frequency • High f -> affected by various medium • Security: dos, unauthorized access and etc. • Wireless medium access control ECE 424

  18. IEEE 802.11 Data Frame ECE 424

  19. Basic Security Strategies • Block your Service Set Identifier (SSID) from being broadcast. • Wireless beacon so PCs can easily find the access point. • Change the default network name in the access point. • Change the default access point password. • Center the access point in the middle of the building/house.

  20. Media Access Control (MAC) Filtering • Every network device has a unique MAC address • Allocated by the manufacturer. • MAC Filtering only allows certain addresses access. • Mostly for home use. • Tedious to implement on a large scale

  21. Wired Equivalency Protocol (WEP) • Basic encryption technology. • Uses an RC4 stream cipher. • Pseudo-random bytes. • Two versions: 64-bit and 128-bit versions. • Built into Wi-Fi certified equipment. • Implemented at the MAC level. • Protects radio signal between device and access point. • Does not protect data beyond the access point. • Uses static encryption keys. • Easy to crack. • Still better then nothing.

  22. Wi-Fi Protected Access (WPA) • Designed to replace WEP. • Firmware update. • 128-bit Temporal Key Integrity Protocol (TKIP) encryption. • Uses a master key that is regularly changed. • User authentication. • Data Integrity. • Protects radio signal between device and access point. • Built into Wi-Fi certified equipment. • Implemented at the MAC level. • Available in two versions: • WPA2 Personal. • WPA2 Enterprise.

  23. Wi-Fi Protected Access 2 (WPA2) • Designed to replace WEP. • 128-bit Advanced Encryption Standard (AES). • Based on the IEEE 802.11i standard. • Provides government level security. • Also available in two versions: • WPA2 Personal. • WPA2 Enterprise.

  24. Wireless Media Access Control • MAC protocol: shared media scheduling • maximize number of communications • Ensure fairness among all transmitters • CSMA – carrier sensing multiple access • CD – collision detection • If (Transmitted_Signal != Sensed_Signal)  Sender knows it’s a Collision  ABORT • Wireless problem • Can not send and listen • Signal not same at same ECE 424

  25. Bluetooth Overview • Bluetooth is a global, RF-based (ISM band: 2.4 GHz), short-range, connectivity solution for portable, personal devices • it is not just a radio, it is an end-to-end solution • The Bluetooth spec comprises • a HW & SW protocol specification • usage case scenario profiles and interoperability requirements • IEEE 802.15.1 is working on standardizing the PHY and MAC layers in Bluetooth • More Info: • http://www.bluetooth.org • http://ieee802.org/15/pub/TG1.html

  26. Bluetooth - Piconet • A collection of devices connected via Bluetooth technology in an ad hoc fashion. • A piconet starts with two connected devices, and may grow to eight connected devices. • All Bluetooth devices are peer units and have identical implementations. However, when establishing a piconet, one unit will act as a Master and the other(s) as slave(s) for the duration of the piconet connection.

  27. The Bluetooth protocols Applications • A hardware/software description • An application framework Other TCS RFCOMM SDP Application Framework and Support Data Control Host Controller Interface Audio L2CAP Link Manager and L2CAP Link Manager Baseband Radio & Baseband RF

  28. Linux Networking • Networking utilities • Ipcofig • Netstat • Socket implementations • Networking kernel structures ECE 424

  29. Linux Network Stack ECE 424

  30. StructSK_buff ECE 424

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