Research into the hybridization of the PRoPHET and ERP network routing
algorithms
George Mason University
INFS 612 (Spring 2013)
Project Group 4: Richard Joy,
Miriam Joy, Serena Mei, and Suyog
Parajuli
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Research Problem
Background on ERP and PRoPHET
Research Approach
Results
Demonstration
Conclusion and Questions
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Delay Tolerant Network (DTN) addresses challenges
in disconnected, disrupted networks without endto-end connection
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Over time, DTN routing protocols have developed in
two areas: forwarding-based and replication-based
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Replication-based algorithms have higher message
delivery rates, but are resource hungry
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Problem: Is there a way to combine two replicationbased algorithms which result in the same delivery
rate with lower overhead?
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Mobile Sensor Networks
 Sensors with wireless connectivity deployed over a geographic area
 Periodically transmit their findings to a base station, perhaps for
analysis or permanent storage.
 These sensors may be small and have limited communication range,
implying that they are not always able to establish a connected path
(leveraging other sensors as routers) back to base stations.
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Disaster Recovery/Military Deployment:
 People, in addition to sensors, are deployed over an area with limited
wireless coverage (i.e., few, if any, base stations).
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Interplanetary/Spacecraft Communications
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ERP is a “greedy” replication algorithm
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Nodes continuously replicate and transmit messages to
newly discovered contacts who do not already possess a
copy
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Very effective at delivering messages
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Extremely inefficient for resources
Time = t1
S
C2
C3
D
C1
Time =
t2>t1
S
C3
C2
C1
D
PRoPHET is a “utility-based” replication protocol
Not indiscriminate in its replication; uses an
adaptive algorithm
 Set of probabilities for successful delivery
 Algorithm updates whenever a node is
encountered.
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 Nodes that are encountered frequently have a high
delivery predictability.
 PRoPHET statistics are shared between each of the
communicating nodes.
Message Source: S
Message Destination: D
B
D
S
D
B
C
S
C
1
2
D
C
S
C
B
S
3
Message
D
B
4
Orbit and probability of encounter
DTNNode
DTNNode
DTN
Listener
Connection
List
In our environment,
the nodes have
particular orbits;
connection
probabilities are
assigned to reflect
this design
DTN
Connector
Message
Stats
JBDC
Connector
Database
Message
Manager
•20 Nodes
•4 connection partners
per node with 25%
probability
•30 messages
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Ran a series of tests incrementing the
threshold for switching to ERP (if it is the
better solution)
Each test (each threshold) was 40 minutes
long
Time-to-live for each message was 128
connections
40 min
100%
PRoPHET
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
100% ERP
0 = 100% ProPHET
600
500
400
300
200
100
# of message deaths
No.of Connections
18,000
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
0
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Threshold
ERP
ProPHET
Message Deaths
1 1 = 100% ERP
Average and maximum message buffer size across all nodes at each
threshold level
8
ERP first selected
by node
7
6
5
4
3
2
1
0
0
0.1
0.2
0.3
0.4
AVG(MESSAGE_COUNT)
0.5
0.6
0.7
0.8
0.9
MAX(MESSAGE_COUNT)
1
12340
2.5
2
1.5
1
0.5
0
12342
12341
8
8
6
6
4
4
2
2
0
0
Threshold
Threshold
12343
Threshold
12344
12345
4
4
8
3
3
6
2
2
4
1
1
2
0
0
0
Threshold
Threshold
Threshold
12346
12347
12348
4
4
8
3
3
6
2
2
4
1
1
2
0
0
0
Threshold
Threshold
12349
8
12350
5
4
3
2
1
0
6
4
2
0
Threshold
Threshold
12351
8
6
4
2
0
Threshold
Threshold
12353
12352
2.5
2
1.5
1
0.5
0
4
8
3
6
2
4
1
2
0
0
Threshold
Threshold
12355
2.5
2
1.5
1
0.5
0
Threshold
12354
Threshold
12356
12357
4
4
3
3
2
2
1
1
0
0
Threshold
Threshold
12358
12359
8
8
6
6
4
4
2
2
0
0
Threshold
Threshold
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Routing Under Uncertainty
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Resource Allocation
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Average latency in delivering messages;
Average amount of system storage and bandwith consumed;
Amount of energy consumed in transmission (particularly applicable to mobile devices
serving as carriers for others)
Reliability
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How do you properly elevate messages for priority handling?
Managing buffers and still maximizing delivery
Integrating a forwarding algorithm
Performance
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Is information on location of target node reliable or being distorted by environmental
conditions? How do you adjust for this?
Sending back acknowledgements from message recipient
Security
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New area of research into “reputation” protocol
How to track messages through the entire path
Encryption