A Comparison of Mechanisms for A Comparison of Mechanisms for Improving Mobile IP Handoff Latency Improving Mobile IP Handoff Latency

for End-to-End TCPfor End-to-End TCP

MobiCom 2003MobiCom 2003Robert Hsieh and Aruna SeneviratneRobert Hsieh and Aruna Seneviratne

School of Electrical Engineering and TelecommunicationsSchool of Electrical Engineering and TelecommunicationsThe University of New South WalesThe University of New South Wales

2626thth February, 2004 February, 2004

Presented by Presented by Sookhyun, YangSookhyun, Yang

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ContentsContents

IntroductionIntroduction

Related WorksRelated Works

Experimental MethodologyExperimental Methodology

Experimental ResultsExperimental Results

ConclusionConclusion

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Mobility Related TerminologyMobility Related Terminology

Mobile node (MN)Mobile node (MN)Handoff (Handover)Handoff (Handover)Layer 2 handoffLayer 2 handoffBeacon messageBeacon message

Access router (AR)Access router (AR)Access network (AN)Access network (AN)

Mobile IP (MIP)Mobile IP (MIP)– Handoff latencyHandoff latency– Home network (HN)Home network (HN)– Foreign (Visited) networkForeign (Visited) network– Home Agent (HA)Home Agent (HA)– Foreign agent (FA)Foreign agent (FA)– Correspondent node (CN)Correspondent node (CN)

INTRODUCTIONINTRODUCTION

Internet draft: http://www.ietf.org/internet-drafts/draft-ietf-seamoby-mobility-terminology-06.txt

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Mobile IP (MIP)Mobile IP (MIP)

When a MN moves and attach itself to When a MN moves and attach itself to another networkanother network– Need to obtain a new IP addressNeed to obtain a new IP address– All existing IP connections to the MN need All existing IP connections to the MN need

to be terminated and then reestablishedto be terminated and then reestablished

Solution to this problem at MIPSolution to this problem at MIP– IndirectionIndirection provided with a set of network provided with a set of network

agentsagents– Handoff latencyHandoff latency

Address reconfigurationAddress reconfiguration procedure procedureHA registrationHA registration process process

– No modification to existing routers or end No modification to existing routers or end correspondent nodescorrespondent nodes

Access point (AP)

Mobile node (MN)

IP

IP’

HA

FACOS

(Care-of-address)

IP

Home network (HN)

Foreign network (FN)

INTRODUCTIONINTRODUCTION

binding

intercept

reconfiguration

tunneling

CN

IP

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MotivationMotivation

Effects of Mobile IP (MIP) handoff latencyEffects of Mobile IP (MIP) handoff latency– Packet lossesPacket losses

– Severe End-to-End TCP performance degradationSevere End-to-End TCP performance degradation

Mitigation of these effects with MIPv6 extensionsMitigation of these effects with MIPv6 extensions– Hierarchical registration managementHierarchical registration management

– Address pre-fetchingAddress pre-fetching

– Local retransmission mechanismLocal retransmission mechanism

No comparative studiesNo comparative studies regarding the relative performance regarding the relative performance amongst MIPv6 extensionsamongst MIPv6 extensions

INTRODUCTIONINTRODUCTION

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OverviewOverview

Evaluate the impact of layer-3 handoff latencyEvaluate the impact of layer-3 handoff latency on End-to-End on End-to-End TCP for various MIPv6 extensionsTCP for various MIPv6 extensions– Hierarchical MIPv6Hierarchical MIPv6

– MIPv6 with Fast-handoverMIPv6 with Fast-handover

– Hierarchical MIPv6 with Fast-handoverHierarchical MIPv6 with Fast-handover

– Simultaneous BindingsSimultaneous Bindings

– Seamless handoff architecture for MIP (S-MIP)Seamless handoff architecture for MIP (S-MIP)

Propose an evaluation modelPropose an evaluation model examining the effect of examining the effect of linearlinear and and ping-pongping-pong movement on handoff latency and TCP goodput movement on handoff latency and TCP goodput

Optimize S-MIPOptimize S-MIP by further eliminating the possibility of packets out by further eliminating the possibility of packets out of orderof order

INTRODUCTIONINTRODUCTION

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Hierarchical Mobile IPv6 (HMIPv6)Hierarchical Mobile IPv6 (HMIPv6)

AR

AR

AP

CN

AP

Minimize HA registration delay!!Minimize HA registration delay!!

RELATED WORKSRELATED WORKS

AR

AR

AR

AR

AR

AP

AR

AR

Access networkAccess network

AR

Internet

HA

Macro mobility

Micro mobility

MAPMAP MAPMAP

Mobility Anchor Point (MAP)

RCOA_1LCOA’

RCOA_1 RCOA_2

RCOA_2LCOA’’

RCOA_1LCOA

binding

binding

Internet draft - http://www.ietf.org/internet-drafts/draft-ietf-mipshop-hmipv6-01.txt

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Local Handoff Latency ReductionLocal Handoff Latency Reduction

Low latency address configurationLow latency address configuration– Reduce address reconfiguration timeReduce address reconfiguration time– Configure an address for MN in an network Configure an address for MN in an network likely to move to before it moveslikely to move to before it moves– UseUse L2 triggerL2 trigger– MethodMethod

Pre-registrationPre-registration– Perform L3 handoff before completion of L2 handoffPerform L3 handoff before completion of L2 handoff

Post-registrationPost-registration– Setup a temporary bi-directional tunnel between oFA and nFASetup a temporary bi-directional tunnel between oFA and nFA– Allow MN to continue using oFA while registration at the time or laterAllow MN to continue using oFA while registration at the time or later

MIPv6 with Fast-HandoverMIPv6 with Fast-Handover– Combined method of pre-registration and post-registrationCombined method of pre-registration and post-registration– Three phasesThree phases

1.1. Handover initiationHandover initiation2.2. Tunnel establishmentTunnel establishment3.3. Packet forwardingPacket forwarding

RELATED WORKSRELATED WORKS

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MIPv6 with Fast-HandoverMIPv6 with Fast-Handover

MN oFA nFA

RtSolPr(Router solicitation proxy)

PrRtAdv(Proxy router advertisement)

F-BU(Fast-binding update)with COA

DisconnectDisconnect

HI(Handover initiation)

ConnectConnectF-NA(Fast neighbor advertisement)

Deliver packets

L2 triggerL2 trigger

F-BAck

Beacon

F-Back(Fast-binding ack)

Hack(Handover ack)

Handoverinitiation

Handoverinitiation

1

TunnelEstablishmentbtw oFA & nFA

TunnelEstablishmentbtw oFA & nFA

2

Forward packets Packet forwardingphase

Packet forwardingphase

3

RELATED WORKSRELATED WORKS

Internet draft - http://www.ietf.org/internet-drafts/draft-ietf-mipshop-fast-mipv6-01.txt

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HMIPv6 with Fast-handoverHMIPv6 with Fast-handover

Combine HMIPv6 with Fast-handoverCombine HMIPv6 with Fast-handover

Reduce latency due to address configuration and HA registrationReduce latency due to address configuration and HA registration

Relocate the forwarding anchor point from oAR to the Relocate the forwarding anchor point from oAR to the MAPMAP

RELATED WORKSRELATED WORKS

nAR

oAR

CN

AR

AR

MAPMAP

AR

AR

AR

nAR

Access networkAccess network

MAPMAP

Internet

HA

ForwardingForwarding

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Simultaneous BindingsSimultaneous Bindings

Reduce packet lossesReduce packet losses

N-casting packets with multiple bindingsN-casting packets with multiple bindings

Forward packets for a short period to the MN’s current location and tForward packets for a short period to the MN’s current location and to n-other locations where the MN is expected move too n-other locations where the MN is expected move to

Forwarding carried by oAR, MAP or HAForwarding carried by oAR, MAP or HA

RELATED WORKSRELATED WORKS

Internet draft- http://www.ietf.org/internet-drafts/draft-elmalki-mobileip-bicasting-v6-05.txt

oAR

nAR1

nAR2

AP (Access point)

MAP

Simultaneousbinding

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Seamless Handoff for MIP (S-MIP)Seamless Handoff for MIP (S-MIP)

Provide a different approach to solve the timing ambiguity problemProvide a different approach to solve the timing ambiguity problem

Build on HMIPv6 with Fast-HandoverBuild on HMIPv6 with Fast-Handover

Use Use MN locationMN location and and movement patternmovement pattern to instruct MN when and to instruct MN when and how handoff is initiatedhow handoff is initiated

Decision engine (DE)Decision engine (DE)– Store the history of MN locationsStore the history of MN locations

– Determine movement patternDetermine movement pattern

– Make “handoff decision” for MNMake “handoff decision” for MN

MAP

MN

oAR

nAR2

nAR1

DE

RELATED WORKSRELATED WORKS

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Decision EngineDecision Engine

HandoffDecision

StochasticLinear

MN locationTracking

Handoff mechanism

<- Signal strength

Stationary near the center

RELATED WORKSRELATED WORKS

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Handoff MechanismHandoff Mechanism

MAP

DE

oAR nAR

MN

S-bufferS-buffer

F-bufferF-buffer

F-packet

S-packet

< SPS mechanism >

Linear movementLinear movement– Synchronized packet simulcasting (SPS)Synchronized packet simulcasting (SPS)– Optimized S-MIPOptimized S-MIP

Stochastical mannerStochastical manner– oAR and nAR are anticipation-modeoAR and nAR are anticipation-mode– Maintain MN’s binding with oAR, nARMaintain MN’s binding with oAR, nAR before before F-NAF-NA– Reduce unnecessary re-setupReduce unnecessary re-setup

Stationary state near the centerStationary state near the center– Establish multiple bindings with ARsEstablish multiple bindings with ARs– MN uses more than one COAs MN uses more than one COAs

RELATED WORKSRELATED WORKS

optimization

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Optimized S-MIPOptimized S-MIP

Elimination of the possibility of packets out of orderElimination of the possibility of packets out of order– Upon sending the Upon sending the F-BUF-BU to the oAR, to the oAR, MNMN must immediately switch to the must immediately switch to the

nARnAR

– After receiving After receiving F-BUF-BU, , oARoAR must immediately forward packets to the nAR must immediately forward packets to the nAR

– oAR oAR only needs to send the only needs to send the FBAckFBAck to the nAR to the nAR

IP packet filtering mechanism at nARIP packet filtering mechanism at nAR– oAR incorrectly forwards IP packets with the S-bit set as f-packetsoAR incorrectly forwards IP packets with the S-bit set as f-packets

– Compare IP packets within the s-buffer and f-buffer at nARCompare IP packets within the s-buffer and f-buffer at nAR

– Discard identical packets in s-bufferDiscard identical packets in s-buffer

– [optimized] Examine 16 bit identification, fragment offset, and flag fields [optimized] Examine 16 bit identification, fragment offset, and flag fields in IP headerin IP header

RELATED WORKSRELATED WORKS

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ImplementationImplementation

SimulatorSimulator– Network Simulator version 2 (ns-allinone2.1b6a)Network Simulator version 2 (ns-allinone2.1b6a)

PatchPatch with the with the nsns wireless extension module allowing basic MIPv4 wireless extension module allowing basic MIPv4

ExtensionExtension to the to the ns-2ns-2– Mobile IPv6 protocolMobile IPv6 protocol– Hierarchical Mobile IPv6 protocol Hierarchical Mobile IPv6 protocol – Fast-handover protocolFast-handover protocol– Simultaneous bindings protocolSimultaneous bindings protocol– Optimized S-MIP protocolOptimized S-MIP protocol

ModificationModification– Infrastructure mode: WaveLan with connection monitor (CMon)Infrastructure mode: WaveLan with connection monitor (CMon)– Additional handoff algorithm: Midway handoffAdditional handoff algorithm: Midway handoff

EXPERIMENTAL METHODOLOGYEXPERIMENTAL METHODOLOGY

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Simulation Network TopologySimulation Network TopologyEXPERIMENTAL METHODOLOGYEXPERIMENTAL METHODOLOGY

Micro mobilityLinear / ping-ping

< Performance focus >• Handoff delay• TCP goodput• CN’s Congestion window

Overall handoff delay (D) =time(first-transmitted~retransmitted)+time(CN->MN)

Max num of packets

recei

ved

by the r

eceive

r in se

quence

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MIPv6 & HMIPv6MIPv6 & HMIPv6EXPERIMENTAL RESULT – Handoff delayEXPERIMENTAL RESULT – Handoff delay

Sender (CN)’s view

Time(seconds)

TCP sequence number

• a: MIPv6 (resolution time 100ms)• b~e: HMIPv6 (resolution time 100ms)• f~I: HMIPv6 (resolution time 200ms)

L2handoff

addressresolution

BUat MAP

Out-of-sequencepacket

• MIP’s D = 814ms• HMIPv6’s D = 326ms

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Fast-HandoverFast-HandoverEXPERIMENTAL RESULT – Handoff delayEXPERIMENTAL RESULT – Handoff delay

Time(seconds)

TCP sequence number

Sender (CN)’s view

• f ~ i : fast-handover (resolution time 100ms)

L2handoff

BU

RtSolPr~PrRtAdv

Proportional to distance (FA~HA)

• D = 358ms• Even though forwarding mechanism, MN is unable to receive packets until the binding update is completed

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HMIPv6 with Fast-HandoverHMIPv6 with Fast-HandoverEXPERIMENTAL RESULT – Handoff delayEXPERIMENTAL RESULT – Handoff delay

TCP sequence number

Time (seconds)

Packet loss due to L2 handoff

Packet forwarding

Out-of-sequence packet

send (ack)

receive (data)

< CN’s cwnd >

D = 270msD = 270ms

Receiver (MN)’s view

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S-MIPS-MIPEXPERIMENTAL RESULT – Handoff delayEXPERIMENTAL RESULT – Handoff delay

Hand off = 100msNo packet loss

No out-of-sequence packet

TCP sequence numberSender (CN)’s view

Time (seconds)

Time (seconds)

TCP sequence number

No packet lossOut-of-sequence packet

<- Optimized S-MIP

Non optimized S-MIP ->

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Handoff DelayHandoff DelayEXPERIMENTAL RESULTEXPERIMENTAL RESULT

MIPMIP

HMIPv6HMIPv6

MIPv6 withFast-handover

MIPv6 withFast-handover

HMIPv6 withFast-handoverHMIPv6 withFast-handover

SimultaneousBindings

SimultaneousBindings

S-MIP (nonop)S-MIP (nonop)

S-MIPS-MIP

814ms814ms

326ms326ms

358ms358ms

270ms270ms

268ms268ms

0ms0ms

0ms0ms

< Linear case > < Ping-pong case >

• Completely break down• Completely break down

• Affected to a lesser extent• Severe throttling

• Affected to a lesser extent• Severe throttling

• Excellent resilience• Excellent resilience

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TCP GoodputTCP GoodputEXPERIMENTAL RESULTEXPERIMENTAL RESULT

MN is stationary near the PAR

Linear : 1.447s

PP: 14.23s

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Congestion WindowCongestion WindowEXPERIMENTAL RESULTEXPERIMENTAL RESULT

Linear movement Ping-ping movement

S-MIPS-MIP

SimultaneousBinding

SimultaneousBinding

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ConclusionConclusion

Analyze various handoff latency reduction frameworkAnalyze various handoff latency reduction framework

Show the possibility of significantly reducing the latency by Show the possibility of significantly reducing the latency by S-MIPS-MIP

Optimize the S-MIP scheme Optimize the S-MIP scheme

Future worksFuture works– S-MIP under multiple connection scenariosS-MIP under multiple connection scenarios

– Scalability of the Decision Engine (DE)Scalability of the Decision Engine (DE)

– Design more sophisticated positioning schemes for S-MIPDesign more sophisticated positioning schemes for S-MIP