The document discusses the evolution and implementation of IPv6 in IoT systems, particularly focusing on low-power and low-rate wireless technologies like IEEE 802.15.4. It highlights key mechanisms such as 6LoWPAN for header compression and issues related to packet size constraints in IoT environments. The emphasis is placed on the shift towards established IP/TCP protocols and the development of a modern IoT gateway blueprint using these technologies.

1. SFSCon 2021
The Rise of IPv6 in IoT
Stefan Schmidt <stefan.schmidt@huawei.com>
Principal Solutions Architect, Huawei OSTC

2. Scope
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Only a glimpse at history and current state of technology in a lightning talk
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Focus for IPv6 enabling in MCU based systems, IPv6 on Linux is a given :-)
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Low-power and low-rate wireless systems

3. History
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Initially only home-grown network protocols, TCP/IP was deemed to wasteful
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Interoperability only through proxy applications, or not at all
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Focus on vertical stacks and isolated sub-networks (no end-to-end)
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IP stacks for microcontroller, e.g. µIP, has been in development for a long time (2003)
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Focused on getting the network stack fit in memory, instead of an optimized frame size
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IEEE 802.15.4 standard released in 2003 as kick-off to explore IP on low-rate and low-power wireless
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IETF started from 2007 onwards to specify IPv6 encapsulation and header compression mechanisms
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6lowpan started with IEEE 802.15.4 and was adopted for many more down the road: Bluetooth, NFC,
PLC, etc
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Key factors are eliding the IPv6 address fields by re-using the L2 addresses and other header
compression techniques

4. 6lowpaninanutshell
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Encapsulation:
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The 6LoWPAN adaptation layer sits between data-link and original network layer
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IPv6 allows for a maximum packet size of 1280 bytes
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Impossible to handle in the 127 byte MTU of IEEE 802.15.4
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Therefore 6lowpan brings back a fragmentation scheme
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But fragmentation can still lead to bad performance in loosy networks, best to avoid
Header Compression:
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Removing information found elsewhere in the frame/packet
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Reduce size by giving up some flexibility
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A few iterations: HC1 & HC2, IPHC, NHC and GHC

5. HeaderSizeProblem
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Worst-case scenario calculations
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Maximum frame size in IEEE 802.15.4: 127 byte
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Reduced by the max. frame header (25 byte): 102 byte
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Reduced by highest link-layer security (21 byte): 81 byte
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Reduced by standard IPv6 header (40 byte): 41 byte
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Reduced by standard UDP header (8 byte): 33 byte
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This leaves only 33 byte for actual payload
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The rest of the space is used by headers
Frame header (25) Llsec (21) IPv6 header (40) UDP Payload (33)
127 Byte

6. 6lowpanHeaderCompression
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IP Header Compression (IPHC) is a core part of 6lowpan
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Defining some default values in IPv6 header
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E.g. version = 6, traffic class & flow-label = 0, hop-limit only well-known values (1, 64 or 255)
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Remove the payload length (available in 6lowpan fragment header or data-link header)
Biggest saving is re-usage of the L2 address for IPv6
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Eliding the IPv6 prefix (global known by network, link-local defined by compression)
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Using the EUI-64 L2 address

7. HeaderSizeSolution
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Calculations with plain 6lowpan usage for optimal case
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IPv6 with link-local and UDP on top
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IPHC with NHC for UDP
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The 48 byte IPv6 + UDP header could in the best cases be reduced to 6 bytes
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Double initial payload
Frame header (25) Llsec (21) IPHC Payload (75)
127 Byte
Dispatch (1) LOWPAN_IPHC (1) LOWPAN_NHC (1) UDP Ports (1)
UDP ports (1) UDP check-sum (2)

8. 6lowpanMiscTips
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Design application protocols and payload to fit into frames and avoid fragmentation
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Enable reliability features in phy and mac layers (IEEE 802.15.4 allows ack/retransmit)
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One lost frame in a bigger packet can have a serious performance impact
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UDP with DTLS to avoid 3 way handshake latencies for TLS connections
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IETF also specifies RFC’s for routing (RPL) and application protocol (CoAP) to fit with
6lowpan

9. Deployments
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Trend to move to established IP/TCP. Known, and proven technology
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Bigger developer base and existing applications
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We already see IPv6-only datacenters with translation at the edge
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Allows IPv6 end-to-end connectivity (or device-to-cloud)
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Already big deployment in isolated deployments, e.g. smart meters
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Push towards smart-homes as well, slowed down due to heterogeneous environments
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Likely to see IPv6-only subnet e.g. a Thread mesh network

10. IoTGatewayBlueprint
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Oniro blueprint to design an IoT Gateway with
modern technology
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Current demo with OpenThread and 6lowpan over IEEE 802.15.4
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Demo video at Huawei booth here at SFSCon
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Work in progress on Matter (former CHIP)
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Zigbee now pushing with Matter and even renamed to CSA
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Possible 6lowpan over BLE use cases

11. IoTGatewayBlueprint
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CoAP
MQTT MQTT
WiFi
Bluetooth Low Energy
OpenThread
OpenThread
WiFi

12. JOIN ONIROPROJECT
Thank you!
Join us @
Huawei booth, SFSCon
oniroproject.org
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