Download Black Hole

An Evaluation of Routing
Reliability in Non-Collaborative
Opportunistic Networks
Ling-Jyh Chen, Che-Liang Chiou, and Yi-Chao Chen
Institute of Information Science, Academia Sinica
{cclljj, clchiou, yichao}@iis.sinica.edu.tw
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Motivation 1/2
• Opportunistic Networks:
– Network contacts are intermittent
– There is rarely an e2e path between the source and
the destination
– Disconnection and reconnection are common
– Link performance is highly variable or extreme
• Potential Applications
– Interconnect mobile search and rescue nodes in
disaster areas
– Allow message exchange in underdeveloped areas
– Permit scientific monitoring of wilderness areas
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Motivation 2/2
• An implicit assumption is usually made in
opportunistic networks: all participating peers
are collaborative.
• Many schemes proposed for data dissemination
are based on the assumption.
• However, there may be uncooperative or
malicious peers in the network, and these
schemes may be vulnerable.
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Our Contribution
• We identify five types of non-cooperative
behaviors: Free Rider, Black Hole,
Supernova, Hypernova, and Wormhole
• We evaluate the impacts of non-cooperative
behaviors on data transmission
performance of three popular opportunistic
network routing schemes.
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Type 1: Free Rider
• A type of selfish behavior
• Use the network to forward data, but
refuse to serve as a relay for others
• Effects:
– Free riders require less memory and energy
than others
– Data transmission performance of the
system degrades due to the reduced
level of collaboration.
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Type 2: Black Hole
• Drop all relayed data without forwarding to other
peers
• Dropping may be:
– Intentional
– Due to a lack of capability, e.g. limited battery power
or buffer size
• Black holes cause data loss
and may significantly degrade
the transmission performance
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Type 3: Supernova
• A type of malicious attack that propagates random
messages destined to other network peers
• Similar to
– Email spamming
– Network worms
– Denial of service attacks
• The malicious traffic
– consume network resources
– interfere with the transmission
of regular messages
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Type 4: Hypernova
• A type of malicious behavior that propagates
random messages intended for virtual peers
that may or may not exist
• The network keeps random messages until
– destination nodes are found or
– they are dropped due to buffer
overflow
• Random messages initiated by
hypernova peers may exist longer
than those by supernova peers.
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Type 5: Wormhole
• Composed of one black hole and one
white hole
– Black holes ‘absorb’ data from others
– White hole ‘radiate’ data as much as they can
• Effects:
– likely to be overloaded
– single-point-of-failure
– security and privacy
issues
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Evaluation Settings
• Evaluate reliability of three opportunistic
network routing schemes:
– Epidemic
– PRoPHET
– HEC-BI
• Simulator: DTNSIM
– A Java-based opportunistic simulator
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Evaluation Settings (cont.)
• Messages:
– generated in the first 10% of the simulation time
– with a Poisson rate of 1,800 seconds/message
– are 1M Bytes
• Data rate: 2Mbps
• Buffer size:
– 1G Bytes for evaluations of free riders and black
holes
– 100 Bytes for evaluations of supernova,
hypernova, and wormholes
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Evaluation Scenarios
• Use two realistic wireless network traces:
– iMote: collected from 2005 Infocom
conference
– UCSD: collected from UCSD campus
Trace Name
iMote
UCSD
Device
iMote
PDA
Network Type
Bluetooth
WiFi
Duration(days)
3
77
Devices participating
274
273
Number of contacts
28,217
195,364
Avg # Contacts/pair/day
0.25148
0.06834
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Evaluation I: Free Riders
- The results indicates that free riders are very harmful to
data transmission in opportunistic networks.
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Evaluation II: Black Hole Peers
- Similar to free riders, the results indicates that black
holes are very harmful to data transmission in
opportunistic networks.
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Evaluation III: Supernova Peers
- The degradation rates in the supernova scenario are much
slower than those in the free rider and black hole scenarios.
- The three schemes are more robust against supernova
behavior than free rider and black hole behavior.
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Evaluation IV: Hypernova Peers
- The effects of supernova and hypernova are similar.
- Hypernova, similar to supernova, has less impact on the
data transmission performance than free riders and black
holes.
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Evaluation V: Wormhole Peers
- Surprisingly, the delivery performance does not degrade as the
percentage of wormholes increases.
- The results indicate that the three schemes are robust against
wormholes, and they can even benefit substantially from wormholes
when the network connectivity is poor.
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Conclusion
• We identify five types of non-cooperative behaviors,
namely free rider, black hole, supernova,
hypernova, and wormhole.
• We evaluate their impacts on Epidemic, ProPHET,
and HEC-BI.
• Data transmission performance degrades
significantly as free rider, black hole, supernova, or
hypernova behavior increases.
• All three routing schemes are robust against
wormhole behavior, and can even benefit from it –
especially when the network connectivity is poor.
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Thanks!
http://www.iis.sinica.edu.tw/~cclljj/
http://nrl.iis.sinica.edu.tw/