challenged networking
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Challenged Networking
An Experimental Study of New Protocols and Architectures
Erik Nordström
Unchallenged Networking
• Wired• Stationary• Conversational• Structured• End-to-end
The Challenges
• Mobile computers• No structures• Intermittent connectivity• No end-to-end paths• No pre-established
names and addresses
How to enable communication when requirements and assumptions change?
The Solutions
• Make existing protocols work better
• Develop new protocols• Make existing and new
protocols interoperable• Develop evaluation
methodologies and testbeds
Main Contributions
• Experimental testbeds and methodologies– Ad hoc Protocol Evaluation (APE)
• Protocol implementation and evaluation– AODV-UU, DSR-UU routing protocols
• New communication paradigms– Interest-based dissemination
• New network architectures– Haggle
Challenges of Experimental Evaluation
• Repeatability– Mobility– Radio
• Management– Scaling– Configuration
• Cross-environment– Simulation, emulation, real-world
Related Work in TestbedsOrbit [Raychaudhuri et. al 2005]
DieselNet [Burgess et. al 2006]
[Above photo (c) 2006 Daily Hampshire Gazette]
•Netbed/Emulab [White et. al 2002]•Whynet [Zhou et. al 2005]•Etc.
Roofnet [Aguayo, et. al 2003]
Experiment Choreography1. Go to position B in the middle of the corridor (5 secs)2. Continue to position C at the end of the corridor (5 secs)3. Go back to starting point (10 secs)
Log SNR
Log traffic
Log parameters
0 1 2 3
Experimental Setup
Relay node swap
Ping!
Routing protocol implementations:•AODV-UU•DSR-UU•OOLSR
Thesis page 204
Link cache poisoning
Mean over 10 experiments
0
3
0
3
Simulation
Real world
Source route at receiver
Source route at sender
Flip-flop routing
DSR-UU
DSR-UU
Source routes
Haggle – An Architecture for Challenged Networking
• Scenario:– People carry information– Ad hoc/opportunistic interactions– Heterogeneous connectivity
• Problems:– How to agree on names and addresses?– How to exchange information?– How to agree on which information to exchange?
The Haggle Approach: Searching
Interests
Interests
Search for matching content
Search for matching content
4 3 21
12 3 4
Interest-based Dissemination
message
interest
Match at least two interests!
Three Interest-based Dissemination Strategies
Wait – only disseminate from source
Content – intermediate nodes may re-disseminate
(forward)
Flood – any node may re-disseminate
What is the Correlation between Contacts and Interests?
List of interests
AffiliationNationality
Technical interests…
3 cm
Trace-based Simulation
1000 messages uniformly spread
over the trace.Match affiliation or
nationality.
Conclusions• Protocols and architectures for challenged networks
cannot be designed solely based on simulations and emulations
• Protocols need to be designed for intermittent connectivity, but they should also exploit full connectivity
• Protocols need to rely more on decision making based on (long term) measurements of the environment, or on a-priori knowledge rather than lookup services
• New naming and addressing schemes required. Schemes that support searching can be attractive for flexible content exchanges
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