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

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 orks (6Lo LoWPAN) WPAN) Chaiporn Jaikaeo chaiporn.j@ku.ac.th Department of Computer Engineering Kasetsart University

Out Outline line 6LoWPAN  IPv6 overview  Header compression tecniques  Routing  JenNet-IP  The 6lo Working Group  2

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

Ex Example ample 6Lo LoWPAN WPAN Sys yste tems ms 4

IP IPv6 6 Ov Overv rvie iew Larger address space compared to IPv6   2 32 vs. 2 128 Autoconfiguration   Supporting both stateful (DHCPv6) and stateless operations Simplified headers   Fixed header with optional daisy-chained headers Mandatory security  5

IPv6 IP 6 He Heade ader Minimum header size = 40 bytes   Header compression mechanism is needed Bit 0 4 8 12 16 20 24 28 0 Ver Flow Label Traffic Class 32 Payload Length Next Header Hop Limit 64 96 Source Address 128 160 192 224 Destination Address 256 288 6

IP IPv6 v6 Ex Exte tended nded He Heade aders rs More flexible than IPv4 ’s option fields  Example 1: no extended header  Next header = 6 (TCP) TCP hdr + payload Example 2: with a routing header  Next header = 6 (TCP) TCP hdr + payload Next header = 43 (routing) 7

IP IPv6 6 Add Addre ressing ing Global unicast addresses   Start with 001 Prefix provided by 001 Host ID Subnet ID service provider 48 16 64  Host ID usually incorporates MAC address 8

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 0 Interface ID 1111 1110 10 96 db c9 FF FE 00 16 fe 10 bits xxxxxxUx U = 0: not unique U = 1: unique 94 db c9 00 16 fe For Ethernet addresses: U=0 Global, U=1: Local 9 See http://upload.wikimedia.org/wikipedia/commons/9/94/MAC-48_Address.svg

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) 10

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 11

6Lo LowPAN wPAN He Heade ader r Sta tack ck 12

He Heade ader r Di Dispat patch ch By Byte te 13

Me Mesh h Add Addre ress He Heade ader r (1) Used with mesh-under routing approach   Only performed by FFDs 14

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  802.15.4 Mesh 802.15.4 Mesh Header Header Header Header B A A D Data D C A D Data Dst Src Orig Final Dst Src Orig Final Originator Final A B C D 15

Mesh sh-unde under r vs. s. Ro Route te-over over Ro Routi ting ng Application Application Transport Transport Network (IPv6) Network (IPv6) Routing 6LoWPAN Adaptation 6LoWPAN Adaptation 802.15.4 MAC 802.15.4 MAC 802.15.4 PHY 802.15.4 PHY Mesh-under routing Route-over routing 16

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  (in 8-byte units) 17

IP IPv6 6 He Heade ader r Comp mpre ress ssion ion Can be either stateless or stateful  Independent of flows  18

HC HC1 1 Comp mpre ression ssion (1) Optimized for link-local addresses  Ver Traffic Class Flow Label Payload Length Next Header Hop Limit Source Address Destination Address 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

HC HC1 1 Comp mpre ression ssion (2) 20

HC2 HC 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 21

HC HC1 1 + HC HC2 2 Comp mpre ression sion 22

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 23

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

IPHC’s Context Identifier Can be used to derive source and  destination addresses Not specified how contexts are stored or  maintained 25

RP RPL L – Ro Routi uting ng Prot otocol ocol for or Low Low-power power an and Lo Lossy Net etworks orks

Lo Low-power power an and d Lo Lossy Ne Netw twor orks ks Abbr. LLN  Packet drops and link Packet delivery ratio  failures are frequent Routing protocol  should not over-react to failures Not only applied to  wireless networks  E.g., power-line communication 27

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  28

LLN LLN Ex Exam ample ple 29

Di Diffe ffere rent nt Obj Objectiv ctive e Fu Func nctions tions - Minimize low and fair quality links - Minimize latency - Avoid non-encrypted links - Avoid poor quality links and battery-powered node 30

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

RPL RP L Ope Opera ratio tions ns DODAG (Destination Oriented Directed Acyclic Graph) is  created Based on the objective function  LBR LBR 1 1 11 12 13 11 12 13 21 22 23 24 21 22 23 24 31 32 33 34 35 31 32 33 34 35 41 42 43 44 45 46 41 42 43 44 45 46 32

Mu Multip ltiple le DOD DODAG AGs (1) Provide alternate routes for different  requirements 33

Mu Multip ltiple le DOD DODAG AGs (2) - High reliability - Low latency (no battery-powered node) 34

Je JenNe nNet IP IP Jennic’s implementation of 6LoWPAN  Supports tree topology  Routing is performed over a tree  35

The 6lo Th 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/ 36

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. 37