Table Of ContentUNIVERSITY OF OSLO
Department of Informatics
User Space Socket
Migration for
Mobile Applications
Master Thesis
Håvard Stigen Andersen
13th May 2012
User Space Socket Migration for Mobile
Applications
Håvard Stigen Andersen
13th May2012
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Acknowledgement
Firstofall,Iwouldliketothankmysupervisors, VeraGoebel,HansVatne
Hansen And Francisco Velázquez for their excellent guidance. Clear and
concisefeedbackhasmadeitpossibleformetocompletethisthesis. Great
supervision on the structure of the thesis and guidance on the proper
writingstylehavehelpedalot.
Iwouldalsoliketothankmyfamilyandfriendsfortheirsupport. Espe-
ciallyathankstoyouthoseofwhohavehelpedmeproofreadingthethesis.
HåvardStigenAndersen
UniversityofOslo
May2012
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Abstract
Nowadays, individuals are surrounded by several personal multimedia
capable devices. This can leverage ubiquitous computing. Yet, in
recent years, multimedia applications have increased their popularity and
demand. Thesetwofactorshavebeenthemainmotivationforcestoretake
process migration research. We focus on process migration to enable
ubiquitous computing with multimedia application requirements, such as
bandwidth andtime constrains. We call applicationsdesigned for process
migration mobile applications. This thesis addresses the connection
mobilitychallengesinprocessmigrationbetweennetworkeddevices,while
fulfillingmultimediaapplicationsrequirements.
We present the design, implementation andevaluation of a user-space
socketmigrationsolutioncalledSOCKMAND.SOCKMANDenablesmobile
applications to resume their connections on other remote nodes after a
migration. The work is motivated by research on process migration for
regular consumers within their own Migration Community, an overlay of
personaldevices. SOCKMANDsupportslegacycorrespondinghosts,hosts
which do not include any logic concerning the socket migration. This is
achieved by introducing a Migration Community Access Point (MCAP).
An MCAP acts as a proxy server between the two endpoints of a socket.
SOCKMANDusesIPinUDPtunnelstotransferpacketsbetweenthe node
with the mobile application and the MCAP. We utilize libpcap and raw
sockets to achieve a user-space implementation. Libpcap and raw sockets
can capture and send raw IP packets from user-space. TCP and UDP
are implemented in user-space. UNIX domain sockets provide the inter-
processcommunicationbetweenmobileapplicationsandSOCKMAND.
WedoourevaluationofSOCKMANDbothbyusinganalyticalmodeling
as well as measurements on our implementation. The measurements
are done on heterogeneous devices to determine if these devices are
capable of running SOCKMAND with multimedia applications, like video
conferencing.
Our evaluation shows that SOCKMAND is capable of utilizing the
full bandwidth of various devices given a large enough packet size. We
show that CPU load in MCAP and endpoints correlate to the number of
packets per second, and not the bandwidth. This shows that application
programmersshoulduselargerpacketsizes,whenpossible,toreduceCPU
load. The round-trip time overhead introduced by Migration Community
Access Points is negligible. SOCKMAND is able to support multimedia
applicationsbasedonourrequirements.
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Contents
1 Introduction 17
1.1 BackgroundandMotivation . . . . . . . . . . . . . . . . . . . . . 17
1.2 ProblemStatement . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.3 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2 Background 19
2.1 MobileApplications . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2 TheTRAMPProject . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2.1 TRAMPReal-timeApplicationMobilityPlatform . . . 20
2.2.2 MigrationCommunities . . . . . . . . . . . . . . . . . . . 21
2.2.3 Real-TimeMultimediaApplications . . . . . . . . . . . 21
2.3 OperatingSystemAbstractions . . . . . . . . . . . . . . . . . . . 22
2.4 UserDatagramProtocol . . . . . . . . . . . . . . . . . . . . . . . 24
2.5 TransmissionControlProtocol . . . . . . . . . . . . . . . . . . . 24
2.6 IPFragmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.7 ConnectionHandover . . . . . . . . . . . . . . . . . . . . . . . . 26
2.8 RequirementAnalysisofBackgroundKnowledge . . . . . . . . 26
3 RelatedWork 29
3.1 SocketMigration . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.1.1 MIGSOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.1.2 SockMi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.1.3 MigratoryTCP . . . . . . . . . . . . . . . . . . . . . . . . 30
3.1.4 ReliableSockets. . . . . . . . . . . . . . . . . . . . . . . . 30
3.1.5 SocketlessTCP . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2 TransportLayerMobility . . . . . . . . . . . . . . . . . . . . . . 31
3.2.1 UPMT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2.2 TCP-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.3 Emerald . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.4 AnalysisofRelatedWork . . . . . . . . . . . . . . . . . . . . . . 32
4 Design 35
4.1 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2 SOCKMAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2.1 MigrationCommunityAccessPoint. . . . . . . . . . . . 36
4.2.2 IPinUDPTunnels . . . . . . . . . . . . . . . . . . . . . . 37
4.2.3 SOCKMANDArchitecture . . . . . . . . . . . . . . . . . 37
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4.2.4 DifferentPacketFlowsThroughSOCKMAND . . . . . 39
4.3 UUIDofaSocket . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.4 MigratingaSocket . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.5 MessagePassingDuringMigration . . . . . . . . . . . . . . . . 41
4.6 IPFragmentationandSOCKMAND . . . . . . . . . . . . . . . . 42
4.7 DetailedDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.7.1 SOCKMANDAPI . . . . . . . . . . . . . . . . . . . . . . . 44
4.7.2 SOCKMANDLibrary . . . . . . . . . . . . . . . . . . . . . 45
4.7.3 UDPController . . . . . . . . . . . . . . . . . . . . . . . . 47
4.7.4 TCPController . . . . . . . . . . . . . . . . . . . . . . . . 47
4.7.5 IPController. . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.7.6 SOCKMANDCore . . . . . . . . . . . . . . . . . . . . . . 48
4.7.7 LibpcapHandler . . . . . . . . . . . . . . . . . . . . . . . 48
4.7.8 RawsocketHandler . . . . . . . . . . . . . . . . . . . . . 48
4.7.9 TunnelHandler . . . . . . . . . . . . . . . . . . . . . . . . 49
4.7.10 SignalHandler . . . . . . . . . . . . . . . . . . . . . . . . 49
4.7.11 MigratorAPI . . . . . . . . . . . . . . . . . . . . . . . . . 49
5 Implementation 51
5.1 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.3 SOCKMANDcomponents . . . . . . . . . . . . . . . . . . . . . . 51
5.3.1 EventHandler. . . . . . . . . . . . . . . . . . . . . . . . . 52
5.3.2 SOCKMANDCore . . . . . . . . . . . . . . . . . . . . . . 53
5.3.3 SOCKMANDAPI . . . . . . . . . . . . . . . . . . . . . . . 58
5.3.4 Libsockmand . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.3.5 UDPController . . . . . . . . . . . . . . . . . . . . . . . . 61
5.3.6 TCPController . . . . . . . . . . . . . . . . . . . . . . . . 65
5.3.7 LibpcapHandler . . . . . . . . . . . . . . . . . . . . . . . 67
5.3.8 MigratorAPI . . . . . . . . . . . . . . . . . . . . . . . . . 68
6 Evaluation 69
6.1 EvaluationGoals. . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
6.2 AnalysisApproach. . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6.3 EvaluationMetrics . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.3.1 CPULoad . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.3.2 Round-TripTime . . . . . . . . . . . . . . . . . . . . . . . 72
6.3.3 SocketMigrationTime . . . . . . . . . . . . . . . . . . . 72
6.3.4 PacketLossintheMCAP . . . . . . . . . . . . . . . . . . 72
6.4 EvaluationFactors . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.4.1 PacketSizes . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.4.2 PacketsperSecond . . . . . . . . . . . . . . . . . . . . . . 73
6.4.3 NodeSpecifications . . . . . . . . . . . . . . . . . . . . . 73
6.4.4 PacketDirectionThroughtheMCAP . . . . . . . . . . . 73
6.5 EvaluationSetups . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
6.5.1 CPULoadofSOCKMANDandMobileApplication . . 74
6.5.2 CPULoadandPacketLossonMCAP . . . . . . . . . . . 76
6.5.3 SocketMigrationTime . . . . . . . . . . . . . . . . . . . 77
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Description:achieved by introducing a Migration Community Access Point (MCAP). can capture and send raw IP packets from user-space. user experience acceptable end to end delay when using video conferencing is 100 ms [2]. of such abstractions are file system management, memory access, inter-.
