Transcript Anycast in Delay Tolerant Networks Yili Gong, Yongqiang Xiong, Qian Zhang, Zhensheng Zhang, Wenjie Wang and Zhiwei Xu Yili Gong Indiana University Globecom, Nov.

Anycast in Delay Tolerant
Networks
Yili Gong,
Yongqiang Xiong, Qian Zhang, Zhensheng Zhang,
Wenjie Wang and Zhiwei Xu
Yili Gong
Indiana University
Globecom, Nov. 29, 2006
Outline
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Introduction
Anycast Routing Metric – EMDDA
Anycast Routing Algorithm
Performance Evaluation
Conclusions & Future Work
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Introduction
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Anycast
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A service that allows a node to send a
message to at least one, and preferably
only one, of the members in a group.
Delay Tolerant Network (DTN)
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No end-to-end contemporaneous path is
guaranteed between any two nodes.
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Challenges
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Uncontrollable movement
The unpredictability of network
connectivity and delay
Limited storage capacity
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Scenario
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Music festival
People cluster to watch performances
Cars, shuttle buses or people move between
clusters
To share music files
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Related Work
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Anycast routing in the Internet and mobile ad
hoc networks
Unicast routing in DTN
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Vahdat and Becker [TR’00]: flooding
Tan [GLOBECOM'03]: SEPR
Zhao [ICC’05]: exploiting non-randomness
movement
Jain [WDTN'05] & Jones [WDTN'05]: MED (Minimum
Expected Delay )
Multicast routing in DTN
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Zhao
[WDTN'05]:
semantics models
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Network Model
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G = (V, E)
An edge e is characterized by
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Source u and destination v
w(u, v): PDF of the departure time of mobile devices
leaving from u to v
d(u, v): Moving delay
c(u, v): Storage capacity of a mobile device
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Assumptions
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Nodes in the network are stationary and
generate messages, while mobile devices do
not generate messages themselves.
On each edge, the mobile devices have the
same storage capacity and moving speed.
On each edge, the departure time of mobile
devices follows Poisson distributions.
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Unicast Routing Metric
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MED (Minimum Expected Delay)
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Average waiting time as the weight of an edge.
PED (Practical Expected Delay)
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Expectation of different paths as the weight.
E(w(s, x))=100
x
d
s
E(w(s, y))=1000
E(w(x, d))=100
y
E(w(y, d))=20
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Anycast Routing Metric
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EMDDA (Expected Multi-Destination Delay
for Anycast )
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Expectation of different paths to different
destinations as the weight.
E(w(s, x))=100
x
E(w(x, d1))=100
d1
s
E(w(s, y))=1000
y
E(w(y, d2))=20
d2
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Anycast Routing Algorithm
Based on EMDDA
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On node u, a message, heading for
anycast group D, is waiting.
When a mobile device is about to leave
for node v,
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If d(u,v)+EMDDA(v,D) < EMDDA(u,D),
then upload the message onto the mobile
device.
Or, do nothing.
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Experiment Setup
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A random graph of 100 nodes
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Generated by Waxman Network Topology Generator
The mean interval time of mobile device leaving on
each edge is selected randomly from 600 to 6,000
seconds.
The moving delay, or single-hop delay, on each edge
is a number between 60 and 600 seconds, which is in
proportion to the distance between the nodes.
Assume that the storage capacities of mobile devices
are the same and they vary from 300 to 800
messages.
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Performance Metrics
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Anycast Delivery Delay (ADD)
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Average Anycast Delivering Delay (AADD)
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The time it takes to route this message from its
sender to any node in its anycast destination
group.
The average ADD of all anycast sessions in the
network.
Average Max Queue Length
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The average of the max queue lengths on all the
nodes.
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CDF of Anycast Delivery Delay (ADD)
Here the mean message inter-arrival time is 100 seconds and the mobile
device storage capacity is 300 messages.
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AADD with Hop Number
Here, the mean message inter-arrival time is 100 seconds and the mobile
device storage capacity is 300 messages.
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Average Max Queue Length
with Mean Message Inter-Arrival Time
Here the mobile device storage capacity is 300 messages.
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Conclusion & Future Work
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Conclusions
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The proposed novel routing metric, EMDDA, depicts the
practical delay for anycast more accurately.
The simulation results show that the routing algorithm based
on EMDDA can reduce the average delay by 11.3% on
average compared to MED and reduce the required storage
by 19.2% on average.
Future Work
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To find the tradeoff between the delivery time and the
storage by adjusting the number of message copies.
To extend the anycast routing algorithm to incorporate both
node storage constraint and network traffic dynamics.
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Any Questions?
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