ITTC Resilient and Survivable Networking The University of Kansas EECS 983 Disruption Tolerance

Resilient and Survivable Networking The University of Kansas EECS 983 Disruption Tolerance James P.G. Sterbenz Department of Electrical Engineering & Computer Science Information Technology & Telecommunications Research Center The University of Kansas jpgs@eecs.ku.edu http://www.ittc.ku.edu/~jpgs/courses/rsnets 23 February 2010 rev. 10.0 2002-2010 James P.G. Sterbenz

Resilient and Survivable Networking Disruption Tolerance DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-2

Disruption Tolerance DT.1 Overview and Definitions DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-3

Disruption Tolerance Definition and Scope Disruption tolerance is the ability of a system to tolerate disruptions in connectivity among its components Disruption tolerance includes tolerance of environmental challenges weak and episodic channel connectivity mobility delay tolerance energy and power constraints 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-4

Disruption Tolerance Relationship to Resilience Disciplines Survivability many targetted failures Fault Tolerance (few random) Challenge Tolerance Traffic Tolerance Disruption Tolerance environmental delay energy mobility connectivity Robustness Complexity Trustworthiness Dependability reliability maintainability safety availability integrity confidentiality Security nonrepudiability AAA auditability authorisability authenticity legitimate flash crowd attack DDoS Performability QoS measures 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-5

Disruption Tolerance DT.2 Weak and Episodic Connectivity DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.2.1 Wireless channel connectivity DT.2.2 Eventual stability DT.2.3 Eventual connectivity DT.2.4 End-to-end transport DT.3 Mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-6

Disruption Tolerance Strong Connectivity Strong connectivity: traditional wired networks continuous connectivity (interruption link failure) unvarying capacity (limited only by cross-traffic) symmetric capacity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-7

Disruption Tolerance Connectivity Challenges Strong connectivity: traditional wired networks continuous connectivity (interruption link failure) unvarying capacity (limited only by cross-traffic) symmetric capacity Challenges to strong connectivity wireless links: noise, interference, jamming mobility: attenuation with increasing range delay: unpredictable delays appear as loss of connectivity energy constraints: dead relay nodes reduce connectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-8

Disruption Tolerance Weak and Episodic Connectivity Strong connectivity: traditional wired networks continuous connectivity (interruption link failure) unvarying capacity (limited only by cross-traffic) symmetric capacity Challenges to strong connectivity wireless, mobility, delay, energy Weak connectivity intermittent connectivity due to mobilty and channel fades time-varying capacity due to interference and attenuation asymmetric connectivity due to unbalanced tranceivers 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-9

Disruption Tolerance Weak and Episodic Connectivity Survivability many targetted failures Fault Tolerance (few random) Challenge Tolerance Traffic Tolerance Disruption Tolerance environmental delay energy mobility connectivity Robustness Complexity Trustworthiness Dependability reliability maintainability safety availability integrity confidentiality Security nonrepudiability AAA auditability authorisability authenticity legitimate flash crowd attack DDoS Performability QoS measures 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-10

Weak and Episodic Connectivity DT.2.1 Wireless Channel Connectivity DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.2.1 Wireless channel connectivity DT.2.2 Eventual connectivity DT.2.3 Eventual stability DT.2.4 End-to-end transport DT.3 Mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-11

Wireless Channel Characteristics Open Channel Open channel subject to attack interference jamming and denial of service injection of bogus signalling and control messages eavesdropping network and traffic analysis 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-12

Wireless Channel Characteristics Connectivity Weak, intermittent, and episodic connectivity limited bandwidth of shared medium time-varying available bandwidth noise, weather (latter for free-space laser as well as RF) episodic connectivity channel fades between bit errors & failed links in consequence difficult to achieve routing convergence 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-13

Weak and Intermittent Connectivity Causes Weak, intermittent, and episodic wireless channel Mobility nodes to move in and out of range Delay unpredictably long delay appears to be disconnection Energy constraints reduce transmission power enforce low duty cycles cause node to die 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-14

Network Connectivity Establishment If possible establish and maintain connectivity self-organisation maintenance 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-15

Network Self-Organisation Overview Establishment of network structure and connectivity auto-configuration of fault-tolerant components self-organisation into resilient, survivable network all infrastructure protocols and signalling must be secure and resistant to attack authenticated use infrastructure when available name servers PKI, CA but don t depend on it: take local actions when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-16

Network Self-Organisation Neighbour Discovery Nodes emit beacons to announce their presence known frequencies and codes used for announcements Establishes set of directly reachable nodes 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-17

Network Self-Organisation Link Formation Pairwise negotiation of link formation interested nodes answer beacons exchange identification, node and link characteristics layer 2 connectivity structure Maintain link adjacencies e.g. keepalive messages 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-18

leaderless cluster abstraction or peer group leader Network Self-Organisation Self-Organisation and Federation Communicating nodes self-organise into federations address acquisition hierarchical cluster formation and leader election based on administrative concerns, security, role/task based bootstrap routing topology 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-19

Network Self-Organisation Network Maintenance On-going operation of network: autonomic self-management self-diagnosis and repair continuing re-optimisation 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-20

Network Self-Organisation Topology Optimisation and Maintenance Topology maintenance of federations merge/split group mobility, dynamic coalitions heal partition 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-21

Network Self-Organisation Topology Optimisation and Maintenance leave then join Topology maintenance of nodes node mobility leave/join from/to federation resolution to identifier vs. topological address reassignment 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-22

Network Connectivity Establishment and LPD Maintain connectivity when practical without sacrificing other requirements won t always be possible [back to that later] Low probability of detection (LPD) low transmission power to limit detection stealthy network is more resistant to attack but stealth makes legitimate communication difficult 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-23

Network Connectivity Topological Connectivity: Transmission Power Transmission Power 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-24 1

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-25 2

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-26 3

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-27 4

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-28 5

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-29 6

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity partitioned islands 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-30 7

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity partitioned islands sufficient connected 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-37 14

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity partitioned islands sufficient connected biconnected 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-39 16

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity partitioned islands sufficient connected biconnected excessive lack of stealth 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-42 19

Network Connectivity Topological Connectivity: Transmission Power Transmission power low: no connectivity partitioned islands sufficient connected biconnected excessive lack of stealth highly connected: self jamming parking lot problem 27 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-50

Network Connectivity Topological Connectivity: Adaptive Power Adaptive transmission power each node adjusts control number of neighbors: degree of connectivity Biconnected graph single link cut avoids partition May be more stealthy in cases of lower transmission power Omnidirectional antennæ 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-51

Network Connectivity Topological Connectivity: Directional Antennæ Directional antennæ focus transmission into sector increase spatial reuse Reduced transmission with better connectivity Increased complexity in: antenna design node discovery MAC protocols (steering) mobility tracking 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-52 1

Network Connectivity Topological Connectivity: Directional Antennæ Directional antennæ focus transmission into sector increase spatial reuse Reduced transmission power with better connectivity Increased complexity in: antenna design node discovery MAC protocols (steering) mobility tracking Increased stealth assuming receiver locations known 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-53 2

Weak and Episodic Connectivity DT.2.2 Eventual Stability DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.2.1 Wireless channel connectivity DT.2.2 Eventual stability DT.2.3 Eventual connectivity DT.2.4 End-to-end transport DT.3 Mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-54

Eventual Stability Routing Convergence and Mobility Current routing algorithms assume eventual stability converge to stable communication paths complete end-to-end path must exist at some point in time link outage treated as failure that must be repaired Moderate mobility is tolerated as a topology change 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-55

Eventual Stability Eventual Stability: Wait for Complete Path destination source Among possible links 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-56 1

Eventual Stability Eventual Stability: Wait for Complete Path Among possible links network is formed biconnected if possible 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-57 2

Eventual Stability Eventual Stability: Wait for Complete Path interference or eavesdropping silent While interference or suspected eavesdropping routing can t converge on a source destination path 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-59 4

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-60 5

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path Routing algorithms recompute and converge 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-61 6

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path Routing algorithms recompute and converge (complete) source destination path exists 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-62 7

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path Routing algorithms recompute and converge (complete) source destination path exists data can be transferred along path (as long as stable) 8 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-63

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path Routing algorithms recompute and converge (complete) source destination path exists data can be transferred along path (as long as stable) 9 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-64

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path Routing algorithms recompute and converge (complete) source destination path exists data can be transferred along path (as long as stable) 10 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-65

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path Routing algorithms recompute and converge (complete) source destination path exists data can be transferred along path (as long as stable) 11 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-66

Eventual Stability Eventual Stability: Wait for Complete Path While interference or suspected eavesdropping routing can t converge on a source destination path Routing algorithms recompute and converge (complete) source destination path exists data can be transferred along path (as long as stable) 12 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-67

Weak and Episodic Connectivity DT.2.3 Eventual Connectivity DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.2.1 Wireless channel connectivity DT.2.2 Eventual stability DT.2.3 Eventual connectivity DT.2.4 End-to-end transport DT.3 Mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-68

Survivable Communication Routing Convergence Need to assume weak and episodic connectivity routine occurrence for which network is designed Resilient communication: eventual connectivity communicate as far as possible, whenever possible hold data when necessary (store-and-forward) deflection when necessary (buffer limitations) schedule transmission for optimum LPI/LPD and energy optimise for eventual stability when possible avoid store-and forward when stable path is available cut-through switches 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-69

interference Eventual Connectivity Eventual Connectivity directional xmit only silent source omni xmit Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-70 1

interference Eventual Connectivity Eventual Connectivity Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-71 2

interference Eventual Connectivity Eventual Connectivity Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible store-and-forward when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-72 3

Eventual Connectivity Eventual Connectivity interference interference silent Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible store-and-forward when necessary directional xmit only 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-73 4

Eventual Connectivity Eventual Connectivity interference Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible store-and-forward when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-74 5

Eventual Connectivity Eventual Connectivity interference interference Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible store-and-forward when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-79 10

interference Eventual Connectivity Eventual Connectivity Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible store-and-forward when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-80 11

interference Eventual Connectivity Eventual Connectivity Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible store-and-forward when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-81 12

interference Eventual Connectivity Eventual Connectivity Multiple interferences or suspected eavesdroppers prevent an end-to-end path from ever existing transfer data as far as possible store-and-forward when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-82 13

Weak and Episodic Connectivity DT.2.4 End-to-End Transport DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.2.1 Wireless channel connectivity DT.2.2 Eventual stability DT.2.3 Eventual connectivity DT.2.4 End-to-end transport DT.3 Mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-85

End-to-End Transport Asymmetric Paths Asymmetric channels result from asymmetric transmission power intentional (LPD) or available power antenna characteristics and directionality terrain and location Unidirectional channels result from asymmetric transmission power radio silence Path connectivity may be episodic Asymmetric and unidirectional E2E concatenation of channels forward and reverse may follow different paths 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-86

End-to-End Transport Asymmetric End-to-End Paths strong symmetric strong asymmetric weak symmetric episodic symmetric episodic asymmetric Asymmetric end-to-end path challenges how to find best paths through network how to characterise entire path strong unidirectional episodic unidirectional 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-87

End-to-End Transport Bidirectional Paths Bidirectional path required for pairwise synchronisation signalling messages bidirectional data communication application issue closed-loop feedback control ACKs for reliable data transfer even if data transfer unidirectional 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-88

End-to-End Transport Open Loop Control Resilience with asymmetric channels needs: open-loop control with feedback only when necessary Open-loop rate control congestion feedback from network only when necessary 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-89

End-to-End Transport Open Loop Error Control Open-loop error control: FEC unreliable transfer optional per link FEC quasi-reliable transfer FEC for probabilistic reliability reliable transfer requires bi-directional path infrequent adaptive selective ACKs distinct from: flow control (E2E) congestion control note: SCTP does none of this 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-90

Flow control End-to-End Transport End-to-End Transport Mechanisms rate that receiver can accept purely end-to-end Congestion control rate that network can accept without congesting network feedback to end systems Error control retransmission of corrupt and lost packets link and network-based error characteristics application-dependent reliability requirements 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-91

End-to-End Transport Explicit Loss/Congestion/Delay Discrimination Absence of expected packet or ACK arrival three distinct and unrelated causes: 1. Congestion: packet dropped in network congestion control: queue overflow (tail drop) congestion avoidance: intentional packet drop 2. Corruption: packet lost or delivered corrupted channel error causing bit errors 3. Delay: packet arrival later than expected store-and-forward delays in disruption tolerant network long path speed-of-light delay in delay-tolerant network very long path around disruption 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-92

End-to-End Transport Discrimination and Explicit Notification Discrimination and proper response essential: congestion back off corruption retransmit delay wait or retransmit via lower delay path Explicit notification ECN: explicit congestion notification ELN: explicit loss notification (due to corruption) ELN cannot be determined from ECN (and vice versa) packet that first causes congestion may then be corrupted EDN: explicit delay notification 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-93

Disruption Tolerance DT.3 Mobility Tolerance and Exploitation DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility DT.3.1 Mobility impacts DT.3.2 Mobility tolerance DT.3.3 Exploiting mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-94

Disruption Tolerance Mobility Survivability many targetted failures Fault Tolerance (few random) Challenge Tolerance Traffic Tolerance Disruption Tolerance environmental delay energy mobility connectivity Robustness Complexity Trustworthiness Dependability reliability maintainability safety availability integrity confidentiality Security nonrepudiability AAA auditability authorisability authenticity legitimate flash crowd attack DDoS Performability QoS measures 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-95

Mobility Tolerance DT.3.1 Mobility Impacts DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility tolerance DT.3.1 Mobility impacts DT.3.2 Mobility tolerance DT.3.3 Exploiting mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-96

Mobility Impact of Mobility 1 Dynamic nodes and topologies changing links, clustering, and federation topology difficult to achieve routing convergence Control loop delay mobility may exceed ability of control loops to react QOS 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-97 1

Mobility Impact of Mobility 2 Dynamic nodes and topologies changing links, clustering, and federation topology difficult to achieve routing convergence Control loop delay mobility may exceed ability of control loops to react Impacts QOS changes in inter-node distance requires power adaptation changes density and impacts degree of connectivity latency issues (routing optimisations temporary) 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-98 2

Mobility Impact of Mobility 3 Dynamic nodes and topologies changing links, clustering, and federation topology difficult to achieve routing convergence Control loop delay mobility may exceed ability of control loops to react Impacts QOS changes in inter-node distance requires power adaptation changes density and impacts degree of connectivity latency issues (routing optimisations temporary) 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-99 3

Mobility Tolerance DT.3.2 Mobility Tolerance DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility tolerance DT.3.1 Mobility impacts DT.3.2 Mobility tolerance DT.3.3 Exploiting mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-100

Mobility Tolerance MANETs MANETs: mobile ad hoc networks EECS 882 MWN-MR alternatives proactive vs. reactive table-driven vs. on-demand tradeoffs overhead of precomputing paths vs. delay of computing path discovery for non-cached path Sufficient for high mobility? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-101

Mobility Tolerance MANETs MANETs: mobile ad hoc networks EECS 882 MWN-MR proactive vs. reactive table-driven vs. on-demand Insufficient for high mobility why? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-102

Mobility Tolerance MANETs MANETs: mobile ad hoc networks EECS 882 MWN-MR proactive vs. reactive table-driven vs. on-demand Insufficient for high mobility: assume moderate mobility network not generally partitioned route discovery can overcome 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-103

Mobility Tolerance Expect Mobility Routing and forwarding expect high mobility use location and trajectory information when available direct information to expected location 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-104

destination Mobility Tolerance Expect Mobility source Routing and forwarding expect mobility Use location/trajectory information where available unicast when predictable (e.g. planetary or racetrack UAV) 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-105 1

destination Mobility Tolerance Expect Mobility source Routing and forwarding expect mobility Use location/trajectory information where available unicast when predictable (e.g. planetary or racetrack UAV) multicast to area of expected location (spray routing) 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-107 3

destination Mobility Tolerance Expect Mobility source Routing and forwarding expect mobility Use location/trajectory information where available unicast when predictable (e.g. planetary or racetrack UAV) multicast to area of expected location (spray routing) 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-108 4

destination Mobility Tolerance Expect Mobility source Routing and forwarding expect mobility Use location/trajectory information where available unicast when predictable (e.g. planetary or racetrack UAV) multicast to area of expected location (spray routing) cluster may have inherent broadcast or epidemic routing 5 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-109

Mobility Tolerance DT.3.3 Exploiting Mobility DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility tolerance DT.3.1 Mobility impacts DT.3.2 Mobility tolerance DT.3.3 Exploiting mobility DT.4 Delay tolerance and DTN DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-110

Mobility Tolerance Exploit Mobility Position node/antenna for survivability use trajectory information when available exert control on movement of other nodes Node can carry data as they move store-and-haul data without radiating transmissions transit areas of no channel connectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-111

interference Mobility Tolerance Exploit Mobility interference source Multiple interferences or suspected eavesdroppers 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-112 1

interference Mobility Tolerance Exploit Mobility interference Multiple interferences or suspected eavesdroppers 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-113 2

interference Mobility Tolerance Exploit Mobility interference Multiple interferences or suspected eavesdroppers 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-114 3

Mobility Tolerance Exploit Mobility interference interference steer move Multiple interferences or suspected eavesdroppers Move nodes and steer antenna around interference 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-115 4

Mobility Tolerance Exploit Mobility interference interference Multiple interferences or suspected eavesdroppers Move nodes and steer antenna around interference 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-117 6

Mobility Tolerance Exploit Mobility interference interference Multiple interferences or suspected eavesdroppers Move nodes and steer antenna around interference Mobile nodes haul data without radiating interference and adversary node avoidance transit disconnectivity store-and-haul 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-124 12

Mobility Tolerance Exploit Mobility interference interference Multiple interferences or suspected eavesdroppers Move nodes and steer antenna around interference Mobile nodes haul data without radiating interference and adversary node avoidance transit disconnectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-126 14

Mobility Tolerance Exploit Mobility interference interference Multiple interferences or suspected eavesdroppers Move nodes and steer antenna around interference Mobile nodes haul data without radiating interference and adversary node avoidance transit disconnectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-127 15

Mobility Tolerance Exploit Mobility interference interference Multiple interferences or suspected eavesdroppers Move nodes and steer antenna around interference Mobile nodes haul data without radiating interference and adversary node avoidance transit disconnectivity 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-128 16

Resilient Communication Adjust Data Transfer to Knowledge Opportunistic epidemic routing protocols transfer data when links are available and nodes reachable but scoped and scheduled to: reduce load while maintaining probability of delivery reduce offered load to network while maintaining goodput Exert control on: node and subnetwork movement protocol and parameter choices layer 2 connectivity and layer 3 federation topology Opportunistic worst case bound; exploit knowledge to improve 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-129

Resilient Communication Adjust Data Transfer to Environment Cut-through (when stable path available) lowest latency for nodes that are capable exploit traditional physical layer techniques Store-and-forward immediate when link available to next node & empty queues move data burst to other nodes for load balancing Store and forward with scheduled transfer wait until link available to next node new physical layer opportunities for burst transfer Store-and-haul data Design for eventual connectivity, optimize for eventual stability 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-130

Disruption Tolerance DT.4 Delay Tolerance DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility DT.4 Delay tolerance and DTN DT.4.1 Delay impacts DT.4.2 IPN and DTNrg evolution DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-131

Disruption Tolerance Unpredictably Long Delay Survivability many targetted failures Fault Tolerance (few random) Challenge Tolerance Traffic Tolerance Disruption Tolerance environmental delay energy mobility connectivity Robustness Complexity Trustworthiness Dependability reliability maintainability safety availability integrity confidentiality Security nonrepudiability AAA auditability authorisability authenticity legitimate flash crowd attack DDoS Performability QoS measures 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-132

Delay Tolerance DT.4.1 Delay Impacts DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility DT.4 Delay tolerance and DTN DT.4.1 Delay impacts DT.4.2 IPN and DTNrg evolution DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-133

Unpredictably Long Delay Impacts 1 Long inter-application delay appears to be disruption long path (c) store-and-forward queueing due to episodic connectivity latency masking techniques mitigate: caching, prefetching but don t always help 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-134

Unpredictably Long Delay Impacts 2 Long inter-application delay appears to be disruption Severely impacts transport and network protocols signalling latencies dominate at high data rates very long control loops long delays may cause data transfer to stall (window-based) wrapped sequence number spaces high-bandwidth- -delay products real-time reaction to many bits in flight difficult or impossible massive buffering required for error control 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-135

Delay Tolerance DT.4.1 IPN and DTNrg Evolution DT.1 Overview and definitions DT.2 Weak and episodic connectivity DT.3 Mobility DT.4 Delay tolerance and DTN DT.4.1 Delay impacts DT.4.2 IPN and DTNrg evolution DT.5 Energy constraints and power management 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-136

Delay Tolerance Satellite and Space Networking Evolution TCP/IP TCP LFN SACK TCPsat SCPS IPN DTN TCP enhancements high performance (LFN long fat networks) [RFC 1323] selective acknowledgements SACK [RFC 2018] TCP over satellite links [RFC 2488, 2760] SCPS: space communication protocol specifications www.scps.org Interplanetary Internet Delay tolerant networking [RFC 4838] bundle protocol [RFC 5050], LTP [RFC 5325 27] 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-137

Delay Tolerance TCP Extensions TCP extensions for long fat networks EECS 881 HSN-TL high bandwidth- -delay paths [RFC 1323] based on earlier [RFC 1072, 1085] Set of TCP extensions implemented as options negotiated to be backward compatible TCP window scale option RTTM: round trip time measurement PAWS: protect against wrapped sequence numbers SACK: selective acknowledgements [RFC 2018] 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-138

LFN TCP Extensions TCP Window Problem on high bandwidth- -delay product path? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-139

LFN TCP Extensions TCP Window Problem on high bandwidth- -delay product path 16 b window size field limits window size to 64 kb much less than bandwidth- -delay product TCP unable to fill pipe, even after slow start Solution? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-140

LFN TCP Extensions TCP Window Scale Option Problem on high bandwidth- -delay product path 16 b window size field limits window size to 64 kb much less than bandwidth- -delay product TCP unable to fill pipe, even after slow start TCP window scale option window scale option (kind = 3, len = 3) 32 bit send and receive window maintained by TCP enables 1 GB windows option offered and accepted in SYN scale factor fixed over connection duration shift.cnt: number of bits to left-shift 16-bit window field 3 3 shift.cnt 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-141

LFN TCP Extensions TCP Round Trip Time Estimate Problem on high bandwidth- -delay product path? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-142

LFN TCP Extensions TCP Round Trip Time Estimate Problem on high bandwidth- -delay product path? one RTT estimate / window not fine-grained enough can cause instability due to aliasing of incorrect samples worse when retransmissions occur Solution? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-143

LFN TCP Extensions TCP Round Trip Time Measurement Problem on high bandwidth- -delay product path? one RTT estimate / window not fine-grained enough can cause instability due to aliasing of incorrect samples worse when retransmissions occur TCP RTTM: round trip time measurement timestamp opt. (kind = 8, len = 10) negotiated in SYN, used in every segment sender inserts current timestamp clock value into TSval receiver puts received TSval into TSecr echo reply of ACK sender 8 10 TSval TSecr 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-144

LFN TCP Extensions TCP Sequence Numbers Problem on high bandwidth- -delay product path? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-145

LFN TCP Extensions TCP Sequence Numbers Problem on high bandwidth- -delay product path 32-bit sequence number can wrap in given flow valid sequence number arrives but from previous flow requirement: 2 31 / B > MSL B [Byte/s], MSL (maximum segment lifetime) [s] example: MSL = 17 s at B = 1 Gb/s Solution? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-146

LFN TCP Extensions TCP Protection Against Wrapped Sequence Problem on high bandwidth- -delay product path 32-bit sequence number can wrap in given flow valid sequence number arrives but from previous flow requirement: 2 31 / B > MSL B [Byte/s], MSL (maximum segment lifetime) [s] example: MSL = 17 s at B = 1 Gb/s TCP PAWS: protection against wrapped sequence # requirement: TCP timestamps option assumption: timestamps monotonically increasing discard segment if timestamp < recently arrived segment 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-147

LFN TCP Extensions TCP Error Control Problem on high bandwidth- -delay product path? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-148

LFN TCP Extensions TCP Error Control Problem on high bandwidth- -delay product path? ARQ penalty and impact of errors increases Solution? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-149

LFN TCP Extensions TCP Selective Acknowledgements Problem on high bandwidth- -delay product path? ARQ penalty and impact of errors increases TCP SACK: selective acknowledgements SACK option negotiated in SYN (kind = 4, len = 2) cumulative ACK behaviour unchanged SACK option (kind = 5, len = 8n+2) for n 3 used when non-contiguous segments rcv indicates byte ranges received positive SACK also useful for wireless links with limited BER 5 8n+2 seq# 1st Byte seq# after last Byte 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-150

Delay Tolerance Satellite Networking Satellite Networking Environment delay long delay for GEO (~280 ms one way uplink+downlink) highly variable delay for MEO and LEO large bandwidth- -delay product limited on-board buffering poor SNR lossy channel with high BER limited and asymmetric bandwidth intermittent connectivity individual satellites not part of switched constellation long burst errors during handoff 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-151

Satellite Networking TCP Applicability TCP/IP TCP LFN SACK TCPsat SCPS IPN DTN TCP over satellite channels TCPsat IETF working group guidelines using standard mechanisms [RFC 2488] use FEC use path MTU discovery carefully due to delay use TCP congestion control + fast retransmit and recovery use window scaling, PAWS, and RTTM use SACK proposed changes and enhancements [RFC 2760] 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-152

Space networking earth station spacecraft spacecraft spacecraft Delay Tolerance Space Networking distances may be much longer than satellite links Problem? 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-153

Space networking earth station spacecraft spacecraft spacecraft Delay Tolerance Space Networking distances may be much longer than satellite links Problem: space links even more challenged 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-154

Space environment Space Networking Environment and Issues high delay due to long distances error-prone links highly asymmetric channels earth spacecraft link may be 2000:1 frequently opposite to application need (e.g. imagery) limited link capacity due to limited energy on spacecraft solar panel generation reduces with distance 2 from sun worse intermittent connectivity long silence periods when occulted (e.g. dark side of moon) schedules for DSN (deep space network) earth stations 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-155

Space Networking Design Goals Delay- and disruption tolerance operate even when not strongly connected tolerate long delays Error tolerance expect and tolerate lossy channels Reduce or eliminate dependence on feedback control avoid stalling while waiting for feedback Minimise round-trips avoid chatty protocols 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-156

Space Networking SCPS Protocol Suite TCP/IP TCP LFN SACK TCPsat SCPS IPN DTN SCPS: space communication protocol specifications CCDS recommendations (Consultative Committee for Space Data Systems) Protocol suite based on Internet protocols SCPS-FP: file transfer protocol SCPS-TP: transport protocol interoperable with TCP SCPS-SP: security protocol SCPS-NP: network protocol SCPS-FP SCPS-TP SCPS-SP SCPS-NP FTP TCP IPsec IP 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-157

SCPS Protocol Suite SCPS-FP SCPS-FP: file transfer protocol standard FTP with enhancements interoperable with standard FTP defaults for space links 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-158

SCPS Protocol Suite SCPS-TP SCPS-TP: transport protocol standard TCP with specified enhancements and options additional SCPS-TP enhancements interoperable with standard FTP SCPT-TP mechanisms congestion control: conventional, Vegas, or rate-based SNACK: selective negative ACK explicit corruption and link outage response loss-tolerant header compression partial reliability record boundary marking 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-159

SCPS Protocol Suite SCPS-NP and SCMP SCPS-NP: network protocol IP like network layer, but not interoperable SCPS-NP/IP gateways required at boundary 32 B header + options IP addresses routing algorithm selectable per packet 8191 B MTU with no fragmentation allowed demux to only 16 transport protocols TOS and 16 precedence layers SCMP control protocol explicit congestion, corruption, and link outage signalling 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-160

Delay Tolerance Interplanetary Networking TCP/IP TCP LFN SACK TCPsat SCPS IPN DTN IPN: Interplanetary Internet architecture developed for interplanetary missions SCPS insufficient for delays O (10 min) 8 40 min RTT to Mars, 2 hr RTT to Jupiter, 20 hr RTT to Pluto ISOC IPN Special Interest Group www.ipnsig.org split into planetary Internets gateways between planetary systems late binding of DNS names custody transfer quasi-reliable transfer without end-to-end ACKs 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-161

Delay Tolerance DTNs TCP/IP TCP LFN SACK TCPsat SCPS IPN DTN DTN: disruption-tolerant network or delay-tolerant network generalisation of IPN concepts and protocol architecture DTNrg from IRTG DTN Research Group www.dtnrg.org discipline of disruption tolerance 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-162

DTNrg Architecture Bundling and Custody Transfer Bundles transferred between gateways Custody transfer between regions no E2E ACKs [BHT+2003] 23 February 2010 KU EECS 983 Resilent & Survivable Nets Disruption RSN-DT-163