This document discusses delay tolerant networks (DTNs) and social-aware routing protocols for DTNs. It begins with an overview of DTNs and their characteristics like intermittent connectivity and lack of end-to-end paths. It then describes the DTN architecture including the bundle layer and bundle protocol. Several categories of DTN routing schemes are presented, including message ferry-based, opportunity-based, and prediction-based. Social-aware routing protocols leverage the social ties between nodes to determine message forwarding. Examples discussed include Epidemic Routing, Spray and Wait, and PROPHET. Performance metrics and the ONE simulator are also summarized.

2. Agenda:
 Internet Assumptions
 Delay Tolerant Network (DTNs)
 DTN Architecture
 Bundle Protocol (BP)
 Functions of BP
 Routing in DTN
 Categories of DTN Routing Schemes
 Social – Aware Routing
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3. Internet Assumptions
 The internet depends upon on some important assumptions:[1]
 Continuous, Bidirectional End-to-end path
 Short Round-Trips
 Symmetric Data Rates
 Low Error Rates
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4. Delay Tolerant Network (DTN)
 Definition
 DTN is an intermittent and also a heterogeneous network, in which
same and different protocols are used for sending and receiving
messages between nodes [2].
 DTN Characteristics:
 Intermittent Connection
 Long/High Delays
 Asymmetric data rate
 High Error Rates
 Lack of End-to-End connectivity
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5. Layered Architecture of DTN [3]
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6. Bundle Layer
 DTN introduces new layer called bundle layer on top of
TCP/IP layer. This layer is responsible for node to node
reliability [3].

7. Bundle Protocol [4]
 Discovered by internet pioneer vint cerf in 2003
 Used as a communication protocol for the purpose of
interplanetary internet.
 The DTN architecture implements store-and-forward message
switching by overlaying a new transmission protocol called the
bundle protocol
 Works on top of lower-layer protocols such as the Internet
protocols .
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8. Function of Bundle Protocol [5]
 Custody Transfer
 Bundle Prioritization
 Bundle Fragmentation
 Bundle Reassembly

9. Custody Transfer [6]

10. Routing in DTN [7]
 On the Internet, the TCP and IP protocols are used throughout
the network.
 In a DTN, all nodes implement both the bundle protocol and a
lower-layer transport protocol.
 Most of the DTN routing methods share a similar pattern, the
“store and forward” fashion.

11. Categories of DTNs routing scheme [8]
 Zhang et.at work on a wide variety of older DTN routing
schemes, and were divided it into two categories.
1. Deterministic case
Future movements, connections and message transmissions
scheduling are completely known in advance.
2. Stochastic case
Future movements, connections and message transmissions
scheduling are completely unknown in advance.
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12. Categories of DTNs routing protocols [9]
From 2003 to 2009, the previous categories were categorized
into three categories which were:
1. Message – ferry – based:
 For message transmission some nodes are used as ferries.
 Used store and forward technique.
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13. Categories of DTNs routing protocols
2. Opportunity – based:
 Message delivered randomly hop by hop.
 Used flooding technique
3. Prediction – based:
 Message delivered on history of observed contacts.
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14. Categories of DTNs routing protocols [10]
Cao et.at works on DTNs routing protocols and divide it into
 Unicast scheme:
Used to deliver message from one source to their destination.
 Multicast scheme:
Used to deliver message from one source to a group of their
interested destinations.
 Any cast scheme:
It is like multicast scheme but the any cast destination is
Any one of the node within the group.
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15. Social Aware Routing Protocol
 The protocols which have the ability of social ties between the
nodes.
 These protocols are used to determine when and where
forward the message.
 These protocols were commonly called social aware or social-
based routing protocols.
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16. Why we need social – aware routing? [11]
 Due to the following problems in DTN we need to use social
aware routing
 Restricted resources
 Unpredictable mobility in DTN
 Used store-carry-forward strategy, the difficulty of this strategy is how
to choose the best relay node and the best time to forward the messages
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17. Social Aware Routing Protocols
1. Epidemic Routing Protocol [12]
 Based on flooding technique
 Multiple copies of the message is created by nodes and
forward the messages to a newly discovered contact with a
hope that it will reach the destination

18. Social Aware Routing Protocols
2. Spray and Wait Routing Protocol [13]
Two phases are involved
 Spray phase
 In this phase, L copies of the message are created by source
node and transfer these messages to L nodes which already do
not have a copy of message.
 If the destination is not found in these L nodes then the schemes
turn to the wait phase .
 Wait phase
 In this phase, the L nodes wait for the destination.
 Once the destination is arrived the message is delivered directly.

19. Social Aware Routing Protocols
3. PROPHET Routing Protocol [14]
 Probabilistic Protocol using History of Encounters and
Transitivity (PROPHET) observed the mobility of the
nodes.
 If a node delivers a message to another node more than
one time, the probability of the transmission of the next
message will be increased to that node

20. Performance Metrics
 Delivery Ratio:
It represents the number of successful message transfers.
 Overhead Ratio:
The number of message transmissions performed for each created
message is called overhead ratio.
 Average latency:
The amount of time taken by the message from source to
destination is called latency.
 Number of hops utilizes / Hop count:
It shows that how many hops are utilized by the protocol.

21. One Simulator [9]
The (Opportunistic Network Environment) ONE is a simulation
environment that is capable of
 Generating node movement using different movement models
 Routing messages between nodes with various DTN routing
algorithms and sender and receiver types

22. Simulation Parameters (Setup Information)
 Simulation time = 5000 s
 Number of host groups = 3,10,20,50,100
 Buffer size = 5 Mb
 Transmit speed = 10 kbps
 Transmit range = 10 m
 Message TTL = 300 minutes

23. Delivery Ratio

24. Delivery Ratio

25. Average Latency

26. Average Latency

27. Overhead Ratio

28. Overhead Ratio

29. Hop Count / Number of Hops Utilized

30. Hop Count / Number of Hops Utilized

31. References:
[1] The Internet Research Task Force’s Delay-Tolerant Networking Research Group
(DTNRG), http://www.dtnrg.org.
[2] Suvarna Patil et al Int “Delay Tolerant Network-Survey Paper” journal of
engineering research and application ISSN:2248-9622,vol.4,issue 2 (version
2)feb,2014, pp. 21-25
[3] 2011Vasco N. G. J. Soares “A layered architecture for Vehicular Delay-Tolerant
Networks”
[4] Adrian Rumpold, Dr. Nils Kammenhuber “Transmission Protocols for Delay-
Tolerant Networks” Seminar FI & IITM SS 2011.
[5] Mukhtar, Omar, “Design and implementation of Bundle protocol stack for Delay-
Tolerant Networking” 2011
[6] http://blog.couble.ovh/DTN-Bundle-Protocol.html
[7] Kaimin Wei, Xiao Liang, and KeXu’ A Survey of Social-Aware Routing Protocols
in Delay Tolerant Networks: Applications, Taxonomy and Design-Related Issue’
COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 16, NO. 1, FIRST
QUARTER 2014
[8] W. Zhao, M. Ammar, and E. Zegura, “Controlling the mobility of multiple data
transport ferries in a delay-tolerant network,” in Proc. 24th IEEE International
Conference on Computer Communications (INFOCOM), 2005.
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32. References:
[9] Ying Zhu, Bin Xu, Member‘’A Survey of Social-Based Routing in Delay Tolerant
Networks: Positive and Negative Social Effects’’ IEEE COMMUNICATIONS
SURVEYS & TUTORIALS, VOL. 15, NO. 1, FIRST QUARTER 2013.
[10]SuvarnaPatil*,Geetha R. Chillerg ‘’Delay Tolerant Networks – Survey Paper’’
Journal of Engineering Research and Applications, Vol. 4, Issue 2( Version 2), February
2014, pp.21-25
[11] Y. Cao and Z. Sun, “Routing in delay/disruption tolerant networks: A taxonomy,
survey and challenges,” IEEE Commun. Surveys Tutorials, vol. 14, no. 3.
[12] Md. Ashif, Abu Rehan”Epidemic routng for Mobile Adhoc Network using
Dijksta’s Algorithms Volume 4,Issue 3 /2016
[13] Guizhu wang,Mei Shao,Run Li,Yao Ma, Bingting Wang” Spray and wait routing
algorithm based on transfer utility of node in DTN”
[14] Thrasyvoulos spyropolos, konstantinos psounis, cauligi S. Raghavendra “ spray
and wait: An efficient routing schemes foe intermittently connected Mobile networks”
[12] www.netlab.tkkfi/tutkimus/dtn/theone/
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