6lowpan final


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6lowpan final

  1. 1. 6LoWPAN Martin Abraham
  2. 2. 6LoWPAN  IPv6 over Low Power Wireless Area Networks  Level 2/3 Protocol (OSI)  Enables usage of IPv6 by wireless embedded devices  Described in IETF RFC 4919, 4944
  3. 3. Device characteristics  Dedicated to specific task/ not general purpose like PCLimited hardware resources:  Low processing power (microcontroller/ dsp)  Little memory  Low powerLimited networks capabilities:  Short range  Low bitrate  Message-Size
  4. 4. Usage scenarios  Building automation  Industrial automation  Logistics  Enviromental Monitoring  Personal/ Health Monitoring  Etc.
  5. 5. Personal Monitoring
  6. 6. Industrial Automation
  7. 7. Home Automation
  8. 8. Protocol history  1980s: Cabled networking - not everthing can be cabled - expensive  Mid 1990s: ~ 20 proprietary solutions (Z-Wave) - scalibility - no interoperability (vendor lock) - bound to specific data-link layer  2003+: ZigBee (IEEE 802.15.4 based) + first wireless standard - scalability (small scale isolated ad hoc networking) - bound to specific data-link layer - not long-lived (quick changes)
  9. 9. Why IPv6?  Long-lived technology (20 years+)  Ability to connect heterogeneous networks  Existing worldwide free-to-use infrastructure  Global scalability  2^128 Bit (16 Byte) Addressing = Enough for Internet of Things  Great number of tools (diagnostic, management etc.)
  10. 10. IPv6 Problems  Bandwidthand Energy efficiency Standard protocol: IEEE 802.15.4 L1/L2 (low bandwidth: 250 kbps, low power: 1mW)  Fragmentation: IPv6 minimum frame size (MTU) = 1280 bytes IEEE 802.15.4 frame size (MTU) = 127 byte (higher bit error rate, failure proneness)  Headercompression: IPv6 headers (40 bytes) reduce payload 53 byte payload in 127 byte 802.15.4 frame
  11. 11. IPv6 Problems  Mobility: Node Mobility and Network Mobility  Reviewof Transport Layer Protocols: TCP inefficient for wireless embedded devices (wireless packet lost)  Handleoffline devices: IP assumes devices are always on, but embedded devices may not (power and duty cycles)  Multicast support: IEEE 802.15.4 & other radios do not support Multicast (expensive)
  12. 12. 6LoWPAN
  13. 13. Fragmentation  Datagram = Basic transfer unit (header, payload)  3 fragmentation header
  14. 14. Fragmentation  Datagram-size: 11bit = 2047 > 1280byte (mininmal IP MTU) Transmitted in every fragment. Destination can reserve memory on first arrival for the whole message  Datagram-tag: 16 bit Sufficient for limited link speed (min. 4 min for repeat)  Datagram-offset:8 bit Offset addressed in 8byte units  2047bytes addressable by 8 bit  Longer messages? Fragmentation handled by standard ip fragmentation (L3)  awsome!
  15. 15. Header compression
  16. 16. Compress IPv6 headers  HC1: IP header  HC2: UDP header  Reduce header size by omissionOmit headers that...  can be reconstructed from L2 layer headers (redundant)  contain information not needed or used in the context (unnessecary)
  17. 17. IPv6 header (6LoWPAN header)
  18. 18. HC1 – Compress IPv6 address  IPv6 address: 64bit prefix | 64bit interface idRemove IPv6 address-prefix:  All nodes in a PAN share single prefix  PAN ID maps to IPv6 prefixRemove IPv6 Interface ID (IID) for local communication:  IID generated from EUID64 (L2)
  19. 19. 6LoWPAN Architecture
  20. 20. Mobility  Micro-Mobility: stay in same ip-domain e.g. switch edge router inside extended 6LoWPAN network  Node-Mobility: Node moves physically between different 6LoWPAN networks e.g. attached to a parcel  Network-Mobility: Full 6LoWPAN networks switches backhaul link handled by edge router
  21. 21. Communication/ BootstrappingHandle offline devices:  Node-initiated communication (to deal with sleep cycles etc.)Bootstrapping/ Multicast/ device constraints:  Roles: Router, Nodes, NEW: Edge Router (take load of devices)  Node Registration/ Node Confirmation replaces Multicast  Duplicate Address Detection done by Edge Router
  22. 22. Conclusion6LoWPAN...  is an open standard  provides an adapter between IEEE 802.15.4 (L1/2) and IPv6 (L3)  enables interoperability between wireless embedded devices (and common Internet devices) using standard protocols  fosters standardization of communication in scope of wireless embedded devices  provides an important foundation for the Internet of Things (IoT)