6lowpan introduction

6lowpan introduction

• 1.
  6LoWPAN Martin Abraham
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  6LoWPAN   IPv6 overLow Power Wireless Area Networks   Level 2/3 Protocol (OSI)   Enables usage of IPv6 by wireless embedded devices   Described in IETF RFC 4919, 4944
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  Device characteristics   Dedicatedto specific task/ not general purpose like PC Limited hardware resources:   Low processing power (microcontroller/ dsp)   Little memory  Low power Limited networks capabilities:   Short range  Low bitrate  Message-Size
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  Usage scenarios   Buildingautomation   Industrial automation   Logistics   Enviromental Monitoring   Personal/ Health Monitoring   Etc.
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  Personal Monitoring
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  Industrial Automation
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  Home Automation
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  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)
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  Why IPv6?   Long-livedtechnology (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.)
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  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)   Header compression: IPv6 headers (40 bytes) reduce payload 53 byte payload in 127 byte 802.15.4 frame
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  IPv6 Problems   Mobility: NodeMobility and Network Mobility   Review of Transport Layer Protocols: TCP inefficient for wireless embedded devices (wireless packet lost)   Handle offline 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)
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  6LoWPAN
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  Fragmentation   Datagram =Basic transfer unit (header, payload)   3 fragmentation header
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  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!
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  Header compression
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  Compress IPv6 headers  HC1: IP header   HC2: UDP header   Reduce header size by omission Omit headers that...   can be reconstructed from L2 layer headers (redundant)   contain information not needed or used in the context (unnessecary)
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  IPv6 header (6LoWPANheader)
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  HC1 – CompressIPv6 address   IPv6 address: 64bit prefix | 64bit interface id Remove IPv6 address-prefix:   All nodes in a PAN share single prefix   PAN ID maps to IPv6 prefix Remove IPv6 Interface ID (IID) for local communication:   IID generated from EUID64 (L2)
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  6LoWPAN Architecture
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  Mobility   Micro-Mobility: stay insame 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
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  Communication/ Bootstrapping Handle offlinedevices:   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
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  Conclusion 6LoWPAN...   is anopen 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)