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6LoWPAN border router :Internship
Maxime DENIS
UMONS
6 December 2012
Masters : Sebastien DAWANS Director : Pr. Bruno QUOITINLaurent DERU
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 1 / 41
Summary
Outline
1 Introduction
2 Evaluation phase
3 Implementation
4 Using the testbed
5 Contiki on Linux
6 Master thesis
7 Conclusion
8 ReferencesMaxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 2 / 41
Introduction Internship subject
Starting point
CETIC border router prototype
The CETIC border router interconnects a WLAN (IPv6) and a WSN(6LoWPAN) using RPL for routing.
FIGURE 1 : The border router in a typical topology.
ModesRouter, hybrid bridge and full bridge.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 3 / 41
Introduction Internship subject
Phases of the internship
1 Documentation :a state of the art ;b documentation of the current implementation.
2 Evaluation :a scenarios : use cases with sequence diagrams ;b performance ;c mobility ;d etc.
3 Implementation :a optimizations ;b adding functionalities.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 4 / 41
Introduction Internship subject
Platforms
FIGURE 2 : Redwire Econotag [1] and ENC28J60[2] Ethernet controller (left),Crossbow Telos B [3] (right).Configuration
Redwire Econotag running the CETIC BR application and an UDPserver on Contiki ;Crossbow Telos B running a simple webserver (Sky websense)and an UDP sender on Contiki.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 5 / 41
Introduction Internship subject
Testbed
FIGURE 3 : CETIC testbed topology allowing multi-hop routing.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 6 / 41
Introduction Notions
6LoWPAN and RPL
6LoWPAN[4, 5]Constitutes an adaption layer between IPv6 and IEEE 802.15.4. Itintroduces packets fragmentation and reassembly, headercompression and Link layer forwarding (in case of mesh undernetworks).RPL [6, 7]Lightweight distance vectorprotocol destined to WSN. Itbuilds a DODAG [8]representing the network.RPL performs a covering ofthe NDP functionalities(Messages : DIO, DIS, DAO).
FIGURE 4 : Example of RPL DODAG.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 7 / 41
Introduction Notions
ContikiDescriptionReal time operating system [9], for embedded platforms. Contiki madeto use only one interface : introduction of a Packet Filter.What Contiki brings
uIP stack : small IPv6 (or IPv4) compliant stack, few RAM ;Protothreads : light threads stackless (blockable).
FIGURE 5 : Changes between standard IPv6 stack and 6LoWPAN stack.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 8 / 41
Introduction CETIC prototype
Structure and modes
RPL
uIPv6
PacketFilter
ENC28J60 802.15.4
FIGURE 6 : CETIC prototypestructure.
1 Packet filter : differencebetween WSN and ethernetdata ;
2 Full bridge mode : switch,forward and translatingll-addresses ;
3 Hybrid bridge mode : switch,ND proxy and multi-hop (inroute-over) ;
4 Router : Prefix announcement,routing, forwarding (twoseparated subnets).
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 9 / 41
Introduction CETIC prototype
Structure and modes
RPL
uIPv6
PacketFilter
ENC28J60 802.15.4
DataTraffic
Translation
RPLTraffic
FIGURE 6 : CETIC prototypestructure.
1 Packet filter : differencebetween WSN and ethernetdata ;
2 Full bridge mode : switch,forward and translatingll-addresses ;
3 Hybrid bridge mode : switch,ND proxy and multi-hop (inroute-over) ;
4 Router : Prefix announcement,routing, forwarding (twoseparated subnets).
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 9 / 41
Introduction CETIC prototype
Structure and modes
RPL
uIPv6
PacketFilter
ENC28J60 802.15.4
RPLMessages
NDPMessages
DataTraffic
Translation
ND-ProxyMulti-hop
FIGURE 6 : CETIC prototypestructure.
1 Packet filter : differencebetween WSN and ethernetdata ;
2 Full bridge mode : switch,forward and translatingll-addresses ;
3 Hybrid bridge mode : switch,ND proxy and multi-hop (inroute-over) ;
4 Router : Prefix announcement,routing, forwarding (twoseparated subnets).
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 9 / 41
Introduction CETIC prototype
Structure and modes
RPL
uIPv6
PacketFilter
ENC28J60 802.15.4
RPLMessages
NDPMessages
DataTraffic
Translation
Multi-hopRoutingTable
FIGURE 6 : CETIC prototypestructure.
1 Packet filter : differencebetween WSN and ethernetdata ;
2 Full bridge mode : switch,forward and translatingll-addresses ;
3 Hybrid bridge mode : switch,ND proxy and multi-hop (inroute-over) ;
4 Router : Prefix announcement,routing, forwarding (twoseparated subnets).
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 9 / 41
Evaluation phase
Outline
1 Introduction
2 Evaluation phaseExample of basic scenarioThe restartSensors mobilityTransparent gateway
3 Implementation
4 Using the testbed
5 Contiki on Linux
6 Master thesis
7 Conclusion
8 References
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 10 / 41
Evaluation phase
Organization of the evaluation phase
FIGURE 7 : Flowcharts of the evaluation phase.
During the phase1 Twelve scenarios defined and explained in documentation,
declined in the three modes of the border router ;2 When a issue was encountered, solutions were designed to
improve prototype.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 11 / 41
Evaluation phase Example of basic scenario
Description
FIGURE 8 : Actors of the scenario.
In a one-sensor topology with border router in hybrid bridge andmanual configuration
1 Wait for the DODAG to be built (typically when a DAO is receivedby the border router) ;
2 Plug the computer to the border router ;3 Start sending pings to the sensor and wait for response.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 12 / 41
Evaluation phase Example of basic scenario
Results
13sbefore
Ethernet
802.15.4BR SkyComputer(router)
User
Echo Request(seq=0)
NA
NS(bbbb::100)
DAD(bbbb::223:dffff:fe97:2492)
DAD(fe80::223:dfff:fe97:2492)RA(bbbb::/64)
Computer connection
DAO
DIO
NA
NS(aaaa::212:7400:1465:f55e)
DIO
DAD(aaaa::250:c2a8:cb76:d81b)
DAD(fe80::250:c2ff:fea8:ced0)
DAD(fe80::250:c2ff:fea8:ced0)
DAD(fe80::250:c2a8:cb76:d81b)
DAD(fe80::250:c2a8:cb76:d81b)
Echo Reply(Seq=0)
Ping to Sky
1
FIGURE 9 : Ping from Computer to Sensor (Sky) through the border router.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 13 / 41
Evaluation phase Example of basic scenario
Results
13sbefore
Ethernet
802.15.4BR SkyComputer(router)
User
Echo Request(seq=0)
NA
NS(bbbb::100)
DAD(bbbb::223:dffff:fe97:2492)
DAD(fe80::223:dfff:fe97:2492)RA(bbbb::/64)
Computer connection
DAO
DIO
NA
NS(aaaa::212:7400:1465:f55e)
DIO
DAD(aaaa::250:c2a8:cb76:d81b)
DAD(fe80::250:c2ff:fea8:ced0)
DAD(fe80::250:c2ff:fea8:ced0)
DAD(fe80::250:c2a8:cb76:d81b)
DAD(fe80::250:c2a8:cb76:d81b)
Echo Reply(Seq=0)
Ping to Sky
2
FIGURE 9 : Ping from Computer to Sensor (Sky) through the border router.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 13 / 41
Evaluation phase Example of basic scenario
Results
13sbefore
Ethernet
802.15.4BR SkyComputer(router)
User
Echo Request(seq=0)
NA
NS(bbbb::100)
DAD(bbbb::223:dffff:fe97:2492)
DAD(fe80::223:dfff:fe97:2492)RA(bbbb::/64)
Computer connection
DAO
DIO
NA
NS(aaaa::212:7400:1465:f55e)
DIO
DAD(aaaa::250:c2a8:cb76:d81b)
DAD(fe80::250:c2ff:fea8:ced0)
DAD(fe80::250:c2ff:fea8:ced0)
DAD(fe80::250:c2a8:cb76:d81b)
DAD(fe80::250:c2a8:cb76:d81b)
Echo Reply(Seq=0)
Ping to Sky
3
FIGURE 9 : Ping from Computer to Sensor (Sky) through the border router.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 13 / 41
Evaluation phase The restart
Bridge in autoconf mode restarting in stable network
Issue encounteredWhen restarting, the border router requests a DODAG (using a DISmessage) and a prefix on the wired network. If it receives a DIO first, itbecomes leaf and root at the same time : loop.
FIGURE 10 : DODAG representation of the network before and afterrestarting.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 14 / 41
Evaluation phase The restart
Solution
Changes to implementation
Increment the version number of the DODAG : the incrementednumber makes the network restarting ;Construct a prefixless DODAG (using link-local address asDODAG ID instead of global address) in autoconfiguration mode ;When a prefix is received from the wired network, add it to theDIO (in Prefix Information Option) and propagate it.
Changes to Contiki
The prefix treatment in a sensor already in a DODAG was defectiveand had to be modified to handle new prefix announced.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 15 / 41
Evaluation phase Sensors mobility
Loss in wireless sensors networks
How can a loss occur ?Sensor problem, interferences, collisions ;Moving topology.
FIGURE 11 : DODAG representation of the network before and after a sensorloss.
Deal with lossesLosses in WSN can occur a lot of time : ETX metric used in RPL.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 16 / 41
Evaluation phase Sensors mobility
Loss in wireless sensors networks
How can a loss occur ?Sensor problem, interferences, collisions ;Moving topology.
FIGURE 11 : DODAG representation of the network before and after a sensorloss.
Deal with lossesLosses in WSN can occur a lot of time : ETX metric used in RPL.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 16 / 41
Evaluation phase Sensors mobility
Loss in wireless sensors networks
How can a loss occur ?Sensor problem, interferences, collisions ;Moving topology.
FIGURE 11 : DODAG representation of the network before and after a sensorloss.
Deal with lossesLosses in WSN can occur a lot of time : ETX metric used in RPL.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 16 / 41
Evaluation phase Sensors mobility
Dealing with lost destinations
Before implementationThe lifetime attribute of the route is used. When lifetime expires, theassociated route is tested and can be removed from the table. Thismechanism prevent any kind of quick mobility among several subnets.
ProposalUse the ETX for descending routes, and remove routes when somecondition are encountered :
The ETX of the neighbor becomes greater than a threshold value ;No-ack penalties are encountered.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 17 / 41
Evaluation phase Transparent gateway
Bridge mode to simplify subnets
FIGURE 12 : Several subnets visible as one subnet with bridge.
Issue encountered with full bridge
On-link prefix announced as off-link, and poorly propagated.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 18 / 41
Implementation
Outline
1 Introduction
2 Evaluation phase
3 Implementation
4 Using the testbed
5 Contiki on Linux
6 Master thesis
7 Conclusion
8 ReferencesMaxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 19 / 41
Implementation
Features added
1 On-link prefix management and propagation (bit set and correctlymanaged by the sensor) ;
2 Incremented DODAG version number correctly managed by thesensors when restart ;
3 Prefix Information Option propagation and management by thesensors ;
4 Route Information Option management by the border router.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 20 / 41
Implementation
Route Information Option management
Option of NDP’s RA message[10] used to set routes in routing tables.
Type Length Pref Len R RP
Route lifetime
Prefix (variable length)
FIGURE 13 : Route Information Option message format as specified in [10].
Before implementationBorder router managing RA but ignoring RIOs.
After implementationWhen a RIO is received from an IPv6 router, announced prefixes areadded to the routing table of the border router, and not spread to theWSN.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 21 / 41
Using the testbed
Outline
1 Introduction
2 Evaluation phase
3 Implementation
4 Using the testbedApplicationEvaluation
5 Contiki on Linux
6 Master thesis
7 Conclusion
8 References
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 22 / 41
Using the testbed Application
Scenario
Two applications1 UDP client running on the sensors, and sending to a server
frequent messages identifying them (each 15s) ;2 UDP server running on the border router, sending an
acknowledgment when receiving a message from a node.
FIGURE 14 : Testbed topology used for the scenario.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 23 / 41
Using the testbed Evaluation
Metrics
What is measured ?PRR from testbed to server : the amount of messages (UDPpackets) sent is compared to the amount of messages received atthe UDP server (running on the border router) ;PRR from server to testbed : the amount of messagesAcknowledgment sent by the server compared to the amount ofmessages received on the sensors ;TCPIP forwarding : the amount of forwards done at each sensor ;CSMA : the amount of CSMA errors encountered at each sensorand through time.
How ?The packet trip is observable using traces all along the stacks (in theapplication, in the uIP stack and in CSMA).
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 24 / 41
Using the testbed Evaluation
Results
FIGURE 15 : Metrics.Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 25 / 41
Using the testbed Evaluation
Results
FIGURE 15 : Metrics.Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 25 / 41
Using the testbed Evaluation
Results
FIGURE 15 : Metrics.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 25 / 41
Using the testbed Evaluation
Analysis
PRRs
Metric Average valuePRRTB→S 99.75%PRRS→TB 98.01%
TABLE 1 : Average results of metrics.
RPL is optimized for collecting data (ascendant traffic).
TCPIP forwardingNodes T2 and T3 used for forwarding by T8 and sometimes by T5.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 26 / 41
Using the testbed Evaluation
RPL routing
RPL is an asymmetric routing protocol which relies on a sink systemfor ascendant traffic and on routes for descendant traffic.
From sensor to border routerThe current implementationuses the default router toforward the packet.
From border router to sensorA lookup is performed to findthe best route to forward thepacket.
FIGURE 16 : Example of traffic on a RPLDODAG.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 27 / 41
Using the testbed Evaluation
RPL routing
RPL is an asymmetric routing protocol which relies on a sink systemfor ascendant traffic and on routes for descendant traffic.
From sensor to border routerThe current implementationuses the default router toforward the packet.
From border router to sensorA lookup is performed to findthe best route to forward thepacket.
FIGURE 16 : Example of traffic on a RPLDODAG.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 27 / 41
Using the testbed Evaluation
RPL routing
RPL is an asymmetric routing protocol which relies on a sink systemfor ascendant traffic and on routes for descendant traffic.
From sensor to border routerThe current implementationuses the default router toforward the packet.
From border router to sensorA lookup is performed to findthe best route to forward thepacket.
FIGURE 16 : Example of traffic on a RPLDODAG.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 27 / 41
Contiki on Linux
Outline
1 Introduction
2 Evaluation phase
3 Implementation
4 Using the testbed
5 Contiki on Linux
6 Master thesis
7 Conclusion
8 ReferencesMaxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 28 / 41
Contiki on Linux
Successful portage of the Contiki’s app to Linux
PlatformBeaglebone using a 700Mhz ARM Cortex A8 [11], relying on theAngstrom distribution [12].
Linux Server
IP Tables
BR
SLIPTAP
RAWEth
RADVDRPL....
802.15.4 Raw or Ctrl (MAC, channel, Ack...)
Telos EthBeaglebone
FIGURE 17 : Linux portage and platform structure.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 29 / 41
Master thesis
Outline
1 Introduction
2 Evaluation phase
3 Implementation
4 Using the testbed
5 Contiki on Linux
6 Master thesisSubjectConcrete applications
7 Conclusion
8 References
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 30 / 41
Master thesis Subject
Subject
What ?Multiple border router problematic : maintain a state betweenseveral border router ;Make border router more simple : using on an higher root(outside the RPL network, in WPAN).
Why ?Redundancy or Traffic engineering ;Run several QoS ;Invisible sink changes (mobility).
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 31 / 41
Master thesis Concrete applications
Redundancy paths and traffic engineering
Load balancing, robustness, etc.
FIGURE 18 : One QoS on same subnet : one instance and several DODAGs.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 32 / 41
Master thesis Concrete applications
Redundancy paths and traffic engineering
Load balancing, robustness, etc.
FIGURE 18 : One QoS on same subnet : one instance and several DODAGs.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 32 / 41
Master thesis Concrete applications
Several QoS
Collecting data, request data, energy-saving paths, etc., on samenetwork
FIGURE 19 : Two QoS on same subnet : several instances.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 33 / 41
Master thesis Concrete applications
Several QoS
Collecting data, request data, energy-saving paths, etc., on samenetwork
FIGURE 19 : Two QoS on same subnet : several instances.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 33 / 41
Master thesis Concrete applications
Invisible sink changes
Same QoS on two separated subnets.
FIGURE 20 : Invisible mobility.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 34 / 41
Master thesis Concrete applications
Invisible sink changes
Same QoS on two separated subnets.
FIGURE 20 : Invisible mobility.Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 34 / 41
Conclusion
Outline
1 Introduction
2 Evaluation phase
3 Implementation
4 Using the testbed
5 Contiki on Linux
6 Master thesis
7 Conclusion
8 ReferencesMaxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 35 / 41
Conclusion
Internship achievements1 Increased border router stability : some optimizations and
bugfixes ;2 Paper :
State of the art (the border router solutions) ;Complete description of the border router and scenarios detailed.
3 Features added :Border router more easily deployable ;Autoconfiguration ;Stability increased.
Master thesis perspectives1 RPL root outside WSN ;2 Mobility, redundancy, traffic engineering.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 36 / 41
Conclusion
Questions ?
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 37 / 41
Conclusion
Demonstration
FIGURE 21 : Configuration.
SummaryBorder router web interface, pings, etc.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 38 / 41
References
[1] “Redwire Econotag.”http://redwirellc.com/store/node/1 (last access :26/09/12).
[2] “ENC28J60.” http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en022889 (last access : 26/09/12).
[3] Crossbow, “Telos b.”http://www.xbow.jp/TelosbCatalog.pdf (last access :1/10/12).
[4] “6LoWPAN Backbone Router.” http://tools.ietf.org/html/draft-thubert-6lowpan-backbone-router-02(last access : 2/10/12).
[5] L. M. Ara, “Neighbor Discovery Proxy-Gateway for6LoWPAN-based Wireless Sensor Networks.” KTM Informationand Communication Technology.
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 39 / 41
References
[6] “RFC 6550 : RPL : IPv6 Routing Protocol for Low-Power andLossy Networks.”https://datatracker.ietf.org/doc/rfc6550/ (lastaccess : 2/10/12).
[7] J.-P. Vasseur and A. Dunkels, Interconnecting smart objects withIP.Morgan Kauffman, 2012.
[8] S. Kuryla, “RPL : IPv6 Routing Protocol for Low power and LossyNetworks.” http://cnds.eecs.jacobs-university.de/courses/nds-2010/kuryla-rpl.pdf (last access :20/09/12), 2010.
[9] “Contiki 2.6 Doxygen.”http://contiki.sourceforge.net/docs/2.6/ (lastaccess : 17/09/12).
Maxime DENIS (UMONS) 6LoWPAN border router : Internship 6 December 2012 40 / 41
References
[10] “RFC 4191 : Default Router Preferences and More-SpecificRoutes.” https://datatracker.ietf.org/doc/rfc4191/(last access : 11/10/12).
[11] “Beaglebone flyer.”http://beagleboard.org/static/flyer_latest.pdf(last access : 3/12/12).
[12] “Angstrom distribution.”http://linuxtogo.org/gowiki/AngstromManual (lastaccess : 3/12/12).
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