(01 0120 20442 4423) ) IPv6 6 ov over er Lo Low-Power Power - - PowerPoint PPT Presentation

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(01 0120 20442 4423) ) IPv6 6 ov over er Lo Low-Power Power - - PowerPoint PPT Presentation

Sep 26, 2022 454 likes •843 views

Net etwork work Ke Kernel el Ar Archit hitectu ectures res and Imp an mplementat ementation ion (01 0120 20442 4423) ) IPv6 6 ov over er Lo Low-Power Power Wi Wireles eless s Per ersonal sonal Ar Area ea Net etworks

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SLIDE 1

Net etwork work Ke Kernel el Ar Archit hitectu ectures res an and Imp mplementat ementation ion (01 0120 20442 4423) ) IPv6 6 ov

  • ver

er Lo Low-Power Power Wi Wireles eless s Per ersonal sonal Ar Area ea Net etworks

  • rks

(6Lo LoWPAN) WPAN)

Chaiporn Jaikaeo chaiporn.j@ku.ac.th Department of Computer Engineering Kasetsart University

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SLIDE 2

Out Outline line

6LoWPAN

IPv6 overview

Header compression tecniques

Routing

JenNet-IP

The 6lo Working Group

2

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SLIDE 3

6Lo LoWPAN WPAN

IPv6 over Lo Low-power Wireless Personal Area Networks

Nodes communicate using IPv6 packets

An IPv6 packet is carried in the payload of IEEE 802.15.4 data frames

3

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SLIDE 4

Ex Example ample 6Lo LoWPAN WPAN Sys yste tems ms

4

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SLIDE 5

IP IPv6 6 Ov Overv rvie iew

Larger address space compared to IPv6

  • 232 vs. 2128

Autoconfiguration

  • Supporting both stateful (DHCPv6) and

stateless operations

Simplified headers

  • Fixed header with optional daisy-chained

headers

Mandatory security

5

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SLIDE 6

IP IPv6 6 He Heade ader

Minimum header size = 40 bytes

  • Header compression mechanism is needed

6 Ver

Bit 0

4 8 12 16 20 24 28

Traffic Class

Flow Label Payload Length

Next Header Hop Limit

Source Address Destination Address 32 64 96 128 160 192 224 256 288

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SLIDE 7

IP IPv6 v6 Ex Exte tended nded He Heade aders rs

More flexible than IPv4’s option fields

Example 1: no extended header

Example 2: with a routing header

7 Next header = 6 (TCP) TCP hdr + payload

Next header = 43 (routing)

TCP hdr + payload Next header = 6 (TCP)

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SLIDE 8

IP IPv6 6 Add Addre ressing ing

Global unicast addresses

  • Start with 001
  • Host ID usually incorporates MAC address

8 Prefix provided by service provider

Subnet ID 48 16

Host ID 001

64

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SLIDE 9

IP IPv6 6 Add Addre ress Sco cope pes

Global addresses

  • Globally routable

Link-local addresses

  • Only used within directly attached network
  • Belonging to FE80::/10 block

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Interface ID

1111 1110 10

10 bits

96 db c9 FF FE 00 16 fe 94 db c9 00 16 fe

U = 0: not unique U = 1: unique

xxxxxxUx For Ethernet addresses: U=0 Global, U=1: Local See http://upload.wikimedia.org/wikipedia/commons/9/94/MAC-48_Address.svg

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SLIDE 10

IE IEEE EE 802 802.15 15.4 4 Re Revis isite ited

Allows 127 bytes MTU

  • Good for buffering cost and low packet error

rate

Supports both 16-bit and 64-bit addresses

Supports both star and mesh topologies

Usually operates in an ad hoc fashion with unreliable links

IEEE 802.15.4 networks are considered Low-power and Lossy Networks (LLN)

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SLIDE 11

6Lo LoWPAN WPAN Ada Adapt ptat ation ion Lay Layer

Needs to make IEEE 802.15.4 comply with IPv6’s MTU size of 1280 bytes

  • IEEE 802.15.4’s MTU is 127 bytes
  • MAC header: ≤ 25 bytes
  • Optional security header: ≤ 21 bytes

Provides three main services

  • Packet fragmentation and reassembly
  • Header compression
  • Link-layer forwarding

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SLIDE 12

6Lo LowPAN wPAN He Heade ader r Sta tack ck

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SLIDE 13

He Heade ader r Di Dispat patch ch By Byte te

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SLIDE 14

Me Mesh h Add Addre ress He Heade ader r (1)

Used with mesh-under routing approach

  • Only performed by FFDs

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SLIDE 15

Me Mesh h Add Addre ress He Heade ader r (2)

Hop left field is decremented by one every hop

  • Frame is discarded when hop left is 0

Address fields are unchanged

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A B C

Originator Final

802.15.4 Header Mesh Header

B

Orig Final Dst Src

A A D Data D

802.15.4 Header Mesh Header

D

Orig Final Dst Src

C A D Data

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SLIDE 16

Mesh sh-unde under r vs.

  • s. Ro

Route te-over

  • ver Ro

Routi ting ng

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Application Transport Network (IPv6) 6LoWPAN Adaptation 802.15.4 MAC 802.15.4 PHY Application Transport Network (IPv6) 6LoWPAN Adaptation 802.15.4 MAC 802.15.4 PHY Mesh-under routing Route-over routing

Routing

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SLIDE 17

Fr Fragm agment ent He Heade ader

Fragmentation is required when IPv6 payload size exceeds that of IEEE 802.15.4 payload limit

All fragments are in units of 8 bytes

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(in 8-byte units)

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SLIDE 18

IP IPv6 6 He Heade ader r Comp mpre ress ssion ion

Can be either stateless or stateful

Independent of flows

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SLIDE 19

HC HC1 1 Comp mpre ression ssion (1)

Optimized for link-local addresses

Based on the following observations

  • Version is always 6
  • IPv6 address’s interface ID can be inferred from MAC

address

  • Packet length can be inferred from frame length
  • TC and flow label are commonly 0
  • Next header is TCP, UDP, or ICMP

19 Ver Traffic Class Flow Label Payload Length

Next Header Hop Limit

Source Address Destination Address

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SLIDE 20

HC HC1 1 Comp mpre ression ssion (2)

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SLIDE 21

HC HC2 2 Comp mpre ression ssion

Compress UDP header

Length field can be inferred from frame length

Source and destination ports are shortened into 4 bits each

  • Given that ports fall in the well-known range of

61616 – 61631

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SLIDE 22

HC HC1 1 + HC HC2 2 Comp mpre ression sion

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SLIDE 23

IP IPHC HC Comp mpre ression sion (1)

HC1 and HC2 are only optimized for link- local addresses

  • Globally routable addresses must be carried

non-compressed

IPHC will be the main compression technique for 6LoWPAN

  • HC1 and HC2 will likely be deprecated

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SLIDE 24

IP IPHC HC Comp mpre ression sion (2)

TF: Traffic class and flow label

NH: Next header

HLIM: Hop limit (0NC, 11,264,3255)

CID: Context Identifier

SAC/DAC: Src/Dst address (stateful or stateless)

SAM/DAM: Src/Dst mode

24

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SLIDE 25

IPHC’s Context Identifier

Can be used to derive source and destination addresses

Not specified how contexts are stored or maintained

25

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SLIDE 26

RP RPL L – Ro Routi uting ng Prot

  • tocol
  • col for
  • r

Low Low-power power an and Lo Lossy Net etworks

  • rks
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SLIDE 27

Lo Low-power power an and d Lo Lossy Ne Netw twor

  • rks

ks

  • Abbr. LLN

Packet drops and link failures are frequent

Routing protocol should not over-react to failures

Not only applied to wireless networks

  • E.g., power-line

communication

27 Packet delivery ratio

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SLIDE 28

Ro Routing uting Re Requ quire irements ments

IETF formed a working group in 2008, called ROLL (Routing over Low-power and Lossy Networks) to make routing requirements

Major requirements include

  • Unicast/multicast/anycast
  • Adaptive routing
  • Contraint-based routing
  • Traffic characteristics
  • Scalability
  • Auto-configuration and management
  • Security

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SLIDE 29

LLN LLN Ex Exam ample ple

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SLIDE 30

Di Diffe ffere rent nt Obj Objectiv ctive e Fu Func nctions tions

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  • Minimize low and fair quality links
  • Avoid non-encrypted links
  • Minimize latency
  • Avoid poor quality links and

battery-powered node

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SLIDE 31

RP RPL L Pro rotocol tocol

IPv6 Routing Protocol for Low-power and Lossy Networks

Designed to be highly modular for flexibility

Employing distance vector mechanism

31

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SLIDE 32

DODAG (Destination Oriented Directed Acyclic Graph) is created

  • Based on the objective function

RP RPL L Ope Opera ratio tions ns

32 1 12 11 23 24 13 21 22 35 34 33 32 31 42 41 44 43 45 46

LBR

1 12 11 23 24 13 21 22 35 34 33 32 31 42 41 44 43 45 46

LBR

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SLIDE 33

Mu Multip ltiple le DOD DODAG AGs (1)

Provide alternate routes for different requirements

33

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SLIDE 34

Mu Multip ltiple le DOD DODAG AGs (2)

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  • Low latency
  • High reliability

(no battery-powered node)

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SLIDE 35

Je JenNe nNet IP IP

Jennic’s implementation of 6LoWPAN

Supports tree topology

Routing is performed over a tree

35

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SLIDE 36

Th The 6lo lo Wo Work rking ing Gr Group up

Works on IPv6 over networks of constrained nodes, such as

  • IEEE 802.15.4
  • ITU-T G.9959
  • Bluetooth LE

https://datatracker.ietf.org/wg/6lo/charter/

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SLIDE 37

Re Refe fere rences nces

  • G. Montenegro, N. Kushalnagar, J. Hui, and D.
  • Culler. Transmission of IPv6 Packets over IEEE

802.15.4 Networks, RFC 4494, September 2007.

NXP Laboratories. JenNet-IP WPAN Stack User Guide (JN-UG-3080 v1.3). 2013.

Jean-Philippe Vasseur and Adam Dunkels. Interconnecting Smart Objects with IP: The Next

  • Internet. Morgan Kaufmann. 2010.

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