David E. Culler University of California, Berkeley

June 2008 WEI short course - L10 IPv6 1

Wireless Embedded InterNetworking

Foundations of Ubiquitous Sensor Networks

IPv6 Extensions for Low power embedded networks

David E. CullerUniversity of California, Berkeley


Decade of Research w/o an ArchitectureWireless Sensor Networks

LinkLinkLinkLink

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TransportTransportTransportTransport

ApplicationApplicationApplicationApplication

2002 2003 2004 2005 2006 2007

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Sensornet Concepts

• Cross-layer compression

• Cross-layer visibility

• Piggybacking

• Optimization for bidirectional links

• Trickle

• ...

All within an IP frameworkAll within an IP frameworkAll within an IP frameworkAll within an IP framework


PrefixPrefix IIDIID

ICMPv6ICMPv6ICMPv6ICMPv6

IPv6 IPv6 BaseBase

IPv6 IPv6 BaseBase

HbH HbH OptOpt

HbH HbH OptOpt RoutingRoutingRoutingRouting FragmeFragme

ntnt

FragmeFragmentnt Dst OptDst OptDst OptDst Opt

128 bits

And a decade of progress

• Large uninterpreted addresses

• Autoconfiguration and management

• Layer 2 bootstrapping and discovery

• Protocol options framework


IP Link ⇒ Broadcast DomainIP Link ⇒ Broadcast DomainIP Link ⇒ Broadcast DomainIP Link ⇒ Broadcast Domain

Structured DecompositionStructured DecompositionStructured DecompositionStructured Decomposition

Embedded IPv6 in Concept

IP Link ⇒ Always OnIP Link ⇒ Always OnIP Link ⇒ Always OnIP Link ⇒ Always OnRetain illusion even when always off

Retain strict modularitySome key cross-layer visibility

IPv6 can support a semi-broadcast link with few changes

IP Link ⇒ “Reliable”IP Link ⇒ “Reliable”IP Link ⇒ “Reliable”IP Link ⇒ “Reliable”Retain best-effort reliability over unreliable links


Solution by Layers

LinkLinkLinkLink•Sending frames between neighboring nodes

NetworkNetworkNetworkNetwork•Configuring large numbers of interfaces

•Efficient transmission of IPv6 datagrams

•Delivering datagrams over multiple hops

•Selecting bi-directional links and forming routes

TransportTransportTransportTransport•Delivering messages between app endpoints


LinkEnabling Communication Between Neighboring Nodes

Minimize idle listeningMinimize idle listeningMinimize idle listeningMinimize idle listening

•Sampled Listening•DARPA, Aloha-PS, B-MAC, X-MAC•Always-on illusion, transmission overhead

•Scheduled•S-MAC, T-MAC, PEDAMACS, TSMP, FPS•Low power when in sync, node join problem

•Hybrid•WiseMAC, SCP-MAC•Always-on and low power

•Abstractions•SP•Implement mechanisms, not policies

NetworkNetworkNetworkNetwork

AbstractionAbstractionAbstractionAbstraction

LinkLinkLinkLink


NetNetNetNet

Link Media MgmtEnabling Communication Between Neighboring Nodes

PhyPhyPhyPhy

LinkLinkLinkLink

Media Management ControlMedia Management ControlMedia Management ControlMedia Management Control

Remote MediaRemote MediaRemote MediaRemote Media Link StatsLink StatsLink StatsLink StatsNeighbor Table

Addr Period Phase Pending RSSI PRR

Local MediaLocal MediaLocal MediaLocal Media

Sample Period

Sample Phase

DatDataa

DatDataa AckAckAckAck

AbstractionAbstractionAbstractionAbstractionProvide the mechanisms

Upper layers define the policy


Link - reviewEnabling Communication Between Neighboring Nodes

OptimizationsOptimizationsPower – Channel Utilization – Average Latency – ThroughputPower – Channel Utilization – Average Latency – Throughput

OptimizationsOptimizationsPower – Channel Utilization – Average Latency – ThroughputPower – Channel Utilization – Average Latency – Throughput

StreamingStreaming SchedulingScheduling

Repairing 15.4 AcksRepairing 15.4 AcksFalse Positives – Security – PayloadFalse Positives – Security – Payload

Repairing 15.4 AcksRepairing 15.4 AcksFalse Positives – Security – PayloadFalse Positives – Security – Payload

15.4 HDR15.4 HDR15.4 HDR15.4 HDR PANPANPANPAN DSTDSTDSTDST SRCSRCSRCSRC SECSECSECSEC TimingTimingTimingTiming PayloadPayloadPayloadPayload 15.4 FTR15.4 FTR15.4 FTR15.4 FTR

Sampled ListeningSampled ListeningStateless – Low Latency – Always On Abstraction – RobustStateless – Low Latency – Always On Abstraction – Robust

Sampled ListeningSampled ListeningStateless – Low Latency – Always On Abstraction – RobustStateless – Low Latency – Always On Abstraction – Robust


AdaptationEfficient Transmission of IPv6 Datagrams

Problem: Small Link MTU, Large IPv6 Problem: Small Link MTU, Large IPv6 DatagramsDatagrams

Problem: Small Link MTU, Large IPv6 Problem: Small Link MTU, Large IPv6 DatagramsDatagrams

•Adaptation Layers•ATM, FireWire, BNEP•Datagram Segmentation, Subnetwork Forwarding

•Header Compression•Flow-based (IPHC, ROHC)•Stateless, shared context (STHD, HHC)

802.15.4 Link802.15.4 Link802.15.4 Link802.15.4 LinkIPv6 DatagramIPv6 Datagram(up to 1280 bytes)(up to 1280 bytes)

IPv6 DatagramIPv6 Datagram(up to 1280 bytes)(up to 1280 bytes) 127 Byte MTU

250 kbps


AutoconfigurationConfiguring Large Numbers of Interfaces

Cur Hop Limit

Managed Addr Config

Other Config

Router Lifetime

Reachable Time

Prefix Length

Autonomous Config

Valid Lifetime

Preferred Lifetime

Prefix

ICMPv6 HdrICMPv6 HdrICMPv6 HdrICMPv6 Hdr Router AdvRouter AdvRouter AdvRouter Adv Prefix InfoPrefix InfoPrefix InfoPrefix Info

RFC 4861 – Neighbor DiscoveryRFC 4861 – Neighbor DiscoveryRFC 4862 – Stateless Addr RFC 4862 – Stateless Addr AutoconfAutoconfRFC 3315 – DHCPv6RFC 3315 – DHCPv6

Existing Options New Options

Network ID

Sequence Number

Router Hops

Flags

MHop MHop InfoInfo

MHop MHop InfoInfo



StatelessStatelessRFC 4861 + 4862RFC 4861 + 4862

StatelessStatelessRFC 4861 + 4862RFC 4861 + 4862

DHCPv6DHCPv6RFC 3315RFC 3315DHCPv6DHCPv6RFC 3315RFC 3315

L2e 00-17-3B-00-39-12-58-28

L2s 0x0001

L3 2001:abcd::1

L2e 00-17-3B-00-57-17-58-39

L2s 0x0023

L3

L2e 00-17-3B-00-79-49-66-23

L2s 0x0092

L3

L2e 00-17-3B-00-57-17-58-39

L2s

L3

L2e 00-17-3B-00-79-49-66-23

L2s

L3

2001:abcd::230x0023

L2e 00-17-3B-00-39-12-58-28

L2s 0x0001

L3 2001:abcd::1

RequestRequestRequestRequest

ResponsResponsee

ResponsResponsee

RequestRequestRequestRequest

ResponsResponsee

ResponsResponsee

2001:abcd::920x0092

2001:abcd::92

2001:abcd::23



Cur Hop Limit

Managed Addr Config

Other Config

Router Lifetime

Reachable Time

Prefix Length

Autonomous Config

Valid Lifetime

Preferred Lifetime

Prefix

ICMPv6 HdrICMPv6 HdrICMPv6 HdrICMPv6 Hdr Router AdvRouter AdvRouter AdvRouter Adv Prefix InfoPrefix InfoPrefix InfoPrefix Info

RFC 4861 – Neighbor DiscoveryRFC 4861 – Neighbor DiscoveryRFC 4862 – Stateless Addr RFC 4862 – Stateless Addr AutoconfAutoconfRFC 3315 – DHCPv6RFC 3315 – DHCPv6

Existing Options New Options

Network ID

Sequence Number

Router Hops

Flags

MHop MHop InfoInfo

MHop MHop InfoInfo

Trickle



LinkLinkLinkLink

NetNetNetNet

TranTranTranTran

AppAppAppApp





Sample Period

Sample Phase

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

StatelesStatelesss

AutoconAutoconff

StatelesStatelesss

AutoconAutoconff

AutoconAutoconff

AutoconAutoconff

DHCPv6DHCPv6DHCPv6DHCPv6

ICMPvICMPv66

ICMPvICMPv66

DatDataa



Routing & Forwarding

NetNetNetNet

RouterRouterRouterRouterRouting Routing ProtocolProtocol

Routing Routing ProtocolProtocol

Routing Routing TableTable

Routing Routing TableTablePrefix Next

ICMPvICMPv66

ICMPvICMPv66

LinkLinkLinkLink

Media Management ControlMedia Management ControlMedia Management ControlMedia Management ControlRemote MediaRemote MediaRemote MediaRemote Media Link StatsLink StatsLink StatsLink Stats

Neighbor Table



Sample Period

Sample Phase

DatDataa


ForwarderForwarderForwarderForwarderMulticastMulticastMulticastMulticast

Send Send ManageManage

rr


rr

BufferBufferBufferBufferUnicastUnicastUnicastUnicast

QueueQueueQueueQueue Forwarding Forwarding TableTable

Forwarding Forwarding TableTablePrefix Next

Default


rr


rr

Delivering datagrams over multiple hopsDelivering datagrams over multiple hopsDelivering datagrams over multiple hopsDelivering datagrams over multiple hops


ForwardingDelivering Datagrams Over Multiple Hops

Minimize energy of reliable delivery to Minimize energy of reliable delivery to next hopnext hop

Minimize energy of reliable delivery to Minimize energy of reliable delivery to next hopnext hop

•Reliability & Rate Control•PSFQ, RMST, Fusion, IFRC, Flush•Hop-by-hop for reliability and control•None with goal of minimizing energy•All assume snooping or broadcast



Hop-by-Hop RecoveryHop-by-Hop RecoveryHop-by-Hop RecoveryHop-by-Hop Recovery

Piggyback L3 Information on L2 AcksPiggyback L3 Information on L2 AcksPiggyback L3 Information on L2 AcksPiggyback L3 Information on L2 Acks

15.4 HDR15.4 HDR15.4 HDR15.4 HDR PANPANPANPAN DSTDSTDSTDST SRCSRCSRCSRC SECSECSECSEC TimingTimingTimingTiming Network InfoNetwork InfoNetwork InfoNetwork Info 15.4 FTR15.4 FTR15.4 FTR15.4 FTR

L3 custody transfer ⇒ fewer msg dropsL3 custody transfer ⇒ fewer msg dropsLower power, lower latency, spatial diversityLower power, lower latency, spatial diversity

1) lookup next hop2) transmit message3) if ack, dequeue, goto 54) backoff5) goto 1



Hop-by-Hop Congestion ControlHop-by-Hop Congestion ControlHop-by-Hop Congestion ControlHop-by-Hop Congestion Control

Less contention ⇒ lower powerLess contention ⇒ lower powerNo snooping or added control overheadNo snooping or added control overhead

1) lookup next hop2) transmit message3) if ack3.1) if not queue full, dequeue, goto 63.2) AIMD backoff, goto 65) backoff6) goto 1

1) lookup next hop2) transmit message3) if ack3.1) if not queue full, dequeue, goto 63.2) AIMD backoff, goto 65) backoff6) goto 1



StreamingStreamingStreamingStreaming Quality of ServiceQuality of ServiceQuality of ServiceQuality of Service

Queue ReservationsQueue Reservations

Latency Tolerant vs. UrgentLatency Tolerant vs. Urgent

IPv6IPv6IPv6IPv6 UrgentUrgentUrgentUrgent PayloaPayloadd

PayloaPayloaddIPv6IPv6IPv6IPv6 PayloaPayloa

dd

PayloaPayloadd

•Disable streaming delays•Reduce backoffs•Disable streaming delays•Reduce backoffs

•Guaranteed service for different classes

•Guaranteed service for different classes

•Reduce power•Increase

throughput

•Reduce power•Increase

throughput


RoutingSelecting Bi-Directional Links and Forming Routes

Problem: Inferring a connectivity graphProblem: Inferring a connectivity graphProblem: Inferring a connectivity graphProblem: Inferring a connectivity graph

•MANET•DSDV, AODV, DYMO, OLSR, TBRPF•Any-to-any, shortest path•Distance vector and link state

•Sensornets•Any-to-any (GPSR, NoGeo, GEM, BVR, S4)•Collection (MintRoute, CTP, MultihopLQI)

•Link Discovery vs. Link Estimation•MANET: assume high mobility•Sensornet: assume a more static network



ForwarderForwarderForwarderForwarderMulticastMulticastMulticastMulticast

Send Send ManagerManager


BufferBufferBufferBuffer

UnicastUnicastUnicastUnicast

QueueQueueQueueQueue Forwarding TableForwarding TableForwarding TableForwarding Table

Prefix Next

Default



RouterRouterRouterRouterRouting Routing ProtocolProtocol


Routing TableRouting TableRouting TableRouting Table

Prefix Next



Default RoutesDefault RoutesDefault RoutesDefault Routes

Discovering LinksDiscovering LinksDiscovering LinksDiscovering LinksICMPv6 HdrICMPv6 HdrICMPv6 HdrICMPv6 Hdr Router AdvRouter AdvRouter AdvRouter Adv MHop InfoMHop InfoMHop InfoMHop Info

Inferring a Connectivity GraphInferring a Connectivity GraphInferring a Connectivity GraphInferring a Connectivity GraphRouting Routing TableTable


Low Routing CostLow Routing Cost

High Routing CostHigh Routing Cost

High ConfidenceHigh Confidence

Low ConfidenceLow Confidence

Selecting a Default RouteSelecting a Default RouteSelecting a Default RouteSelecting a Default RouteRouting Routing TableTable


Forwarding Forwarding TableTable

Forwarding Forwarding TableTablePrefix Next

Default

•Top candidateTop candidate•Dynamic re-Dynamic re-routingrouting•Increasing Increasing confidenceconfidence



IPv6IPv6IPv6IPv6PayloadPayloadPayloadPayload



Supported Supported CommunicationCommunication

Supported Supported CommunicationCommunication

•Sensornet → External IP•External IP → Sensornet•Sensornet → Sensornet•Direct single hop

Most commonMost commonpatterns in sensornetspatterns in sensornets

Most commonMost commonpatterns in sensornetspatterns in sensornets


Routing & ForwardingSelecting Links and Forming Routes

LinkLinkLinkLink

NetNetNetNet

TranTranTranTran

AppAppAppApp





Sample Period

Sample Phase

StatelesStatelesss

AutoconAutoconff

StatelesStatelesss

AutoconAutoconff

AutoconAutoconff

AutoconAutoconff


6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

ICMPvICMPv66

ICMPvICMPv66

DatDataa


ForwarderForwarderForwarderForwarder

MulticastMulticastMulticastMulticast


rr


rr




Prefix Next

Default


rr


rr

RouterRouterRouterRouter






TransportCommunication Between Application Endpoints

LinkLinkLinkLink

NetNetNetNet

TranTranTranTran

AppAppAppApp





Sample Period

Sample Phase






StatelesStatelesss

AutoconAutoconff

StatelesStatelesss

AutoconAutoconff

AutoconAutoconff

AutoconAutoconff


UDPUDPUDPUDP TCPTCPTCPTCP

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

ICMPvICMPv66

ICMPvICMPv66

DatDataa





rr


rr




Prefix Next

Default


rr


rr


Programming Interface

BSD Sockets ⇒ Event based UDPBSD Sockets ⇒ Event based UDPBSD Sockets ⇒ Event based UDPBSD Sockets ⇒ Event based UDP

event void Boot.booted() {call Udp.bind( 7 ); }event void Boot.booted() {call Udp.bind( 7 ); } event void Udp.recvfrom( void *buf, uint16_t len, event void Udp.recvfrom( void *buf, uint16_t len, sockaddr_in6_t *from, sockaddr_in6_t *from, link_metadata_t link_metadata_t *linkmsg ) { *linkmsg ) { call Udp.sendto( buf, len, from ); }call Udp.sendto( buf, len, from ); }

event void Boot.booted() {call Udp.bind( 7 ); }event void Boot.booted() {call Udp.bind( 7 ); } event void Udp.recvfrom( void *buf, uint16_t len, event void Udp.recvfrom( void *buf, uint16_t len, sockaddr_in6_t *from, sockaddr_in6_t *from, link_metadata_t link_metadata_t *linkmsg ) { *linkmsg ) { call Udp.sendto( buf, len, from ); }call Udp.sendto( buf, len, from ); }


Programming Interface

BSD Sockets ⇒ Event based TCPBSD Sockets ⇒ Event based TCPBSD Sockets ⇒ Event based TCPBSD Sockets ⇒ Event based TCP

uint8_t m_buf[ BUF_SIZE ]; uint8_t m_buf[ BUF_SIZE ]; event void Boot.booted() { event void Boot.booted() {

call Tcp.bind( 7 );call Tcp.bind( 7 ); call Tcp.listen(); } call Tcp.listen(); } event bool Tcp.accept( sockaddr_in6_t *to, void **sendbuf, event bool Tcp.accept( sockaddr_in6_t *to, void **sendbuf,

uint16_t *sendbuf_size ) { uint16_t *sendbuf_size ) { *sendbuf = m_buf;*sendbuf = m_buf;

*sendbuf_size = sizeof(m_buf);*sendbuf_size = sizeof(m_buf); return TRUE; } return TRUE; } event void Tcp.connected() {} event void Tcp.connected() {} event uint16_t Tcp.recv( void *buf, uint16_t len ) { event uint16_t Tcp.recv( void *buf, uint16_t len ) {

return call Tcp.send( buf, len ) == SUCCESS ? len : 0; } return call Tcp.send( buf, len ) == SUCCESS ? len : 0; } event void Tcp.acked() {} event void Tcp.acked() {} event void Tcp.closed() { signal Boot.booted(); }event void Tcp.closed() { signal Boot.booted(); }

uint8_t m_buf[ BUF_SIZE ]; uint8_t m_buf[ BUF_SIZE ]; event void Boot.booted() { event void Boot.booted() {

call Tcp.bind( 7 );call Tcp.bind( 7 ); call Tcp.listen(); } call Tcp.listen(); } event bool Tcp.accept( sockaddr_in6_t *to, void **sendbuf, event bool Tcp.accept( sockaddr_in6_t *to, void **sendbuf,

uint16_t *sendbuf_size ) { uint16_t *sendbuf_size ) { *sendbuf = m_buf;*sendbuf = m_buf;

*sendbuf_size = sizeof(m_buf);*sendbuf_size = sizeof(m_buf); return TRUE; } return TRUE; } event void Tcp.connected() {} event void Tcp.connected() {} event uint16_t Tcp.recv( void *buf, uint16_t len ) { event uint16_t Tcp.recv( void *buf, uint16_t len ) {

return call Tcp.send( buf, len ) == SUCCESS ? len : 0; } return call Tcp.send( buf, len ) == SUCCESS ? len : 0; } event void Tcp.acked() {} event void Tcp.acked() {} event void Tcp.closed() { signal Boot.booted(); }event void Tcp.closed() { signal Boot.booted(); }


Stack Architecture

LinkLinkLinkLink

NetNetNetNet

TranTranTranTran

AppAppAppApp





Sample Period

Sample Phase






StatelesStatelesss

AutoconAutoconff

StatelesStatelesss

AutoconAutoconff

AutoconAutoconff

AutoconAutoconff


UDPUDPUDPUDP TCPTCPTCPTCP

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

6Lo

WPA

N A

dap

tati

on

ICMPvICMPv66

ICMPvICMPv66

DatDataa


????????????

HTTPHTTPHTTPHTTP TelnetTelnetTelnetTelnet SNMPSNMPSNMPSNMP DNSDNSDNSDNS ????????????




rr


rr




Prefix Next

Default


rr


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Documents

David E. Culler University of California, Berkeley